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Transcript
Velvetleaf (Mallow) Malvaceae family Abutilon theophrasti by Mike Cowbrough François Tardif Jocelyne Letarte Grain Farmers of Ontario 679 Southgate Drive Guelph, Ontario, Canada, N1G 4S2 www.gfo.ca Tel.: 519-767-9713 or 1-800-265-0550 Photo Credits: Peter Smith, Mike Cowbrough, Annalee Winter, Meghan Grguric, Leanne Freitag, Darren Robinson, Mike Veenema, Christy Shropshire, Michelle Arsenault, www.bugwood.org, and Doug Richards. INTRODUCTION S ince I began a career in weed science over 20 years ago, my three “go to” weed identification books have been “Ontario Weeds”, “Weeds of Quebec” and “Weeds of the NorthEast”. In the mid 2000s, Peter Smith and I wrote a small weed ID guide: “A field guide to grassy and broadleaf weeds” mainly so that we could experiment with macro photography and a section called “I know it’s not … because” where we could spell out the specific characteristics that made a plant different from similar looking species. That section was well received by farmers, agronomists and aspiring weed scientists. So for the “Weed ID Guide for Ontario Field Crops” François, Jocelyne and I have tried to take the best of all those guides and create what we hope is a comprehensive field guide to easy weed identification. This book is for people who work in agriculture and are hoping to minimize the impact that weeds have on their crops. There are literally hundreds of other species we could have included in this book, but we wanted to focus on species that are commonly found in agricultural areas or that are common in Ontario and may pose a risk to human health (such as rashes and blisters caused by giant hogweed or wild parsnip). Perhaps one day, a “Volume Two” will be created that has more species, but for now this should cover most of your needs. If you’re a plant taxonomist, please accept my apologies, we’ve taken many liberties with describing different plant species in this book at the expensive of, undoubtedly, technical accuracy. I have great respect for those trained in the classification of plants and the attention to detail that it requires. I would hope that this book sparks an interest in some to pursue plant taxonomy so that in another 20 years they can write a better, more accessible and technically accurate book then this one. A special acknowledgement to Peter Smith and Annalee Winter who were instrumental in making this field guide a reality. Peter is a good friend, a hard worker and a talented photographer who has made many behind the scenes contributions to Ontario Agriculture. Annalee worked as a summer assistant with me for two seasons and laid the foundation for many of the weed profiles in this guide. I cannot say enough good things about Annalee, she is an impressive and remarkable person. Mike Cowbrough ABOUT THE AUTHORS MIKE COWBROUGH Growing up on a beef and crop farm, Mike aspired to be a professional football or rugby player. Unfortunately there was not a great demand for 5'7" players of average skill in either sport so he decided to pursue a career in weed science instead. A graduate of the University of Guelph (BSc., 1998 and MSc., 2001) Mike began his career in the Crop Protection Industry and then in 2002 moved to his current role as weed specialist (field crops) with the Ontario Ministry of Agriculture, Food and Rural Affairs. He is the recipient of the 2009 Award for Excellence in Weed Science Extension presented by the Canadian Weed Science Society and the 2012 T.R. Hilliard Award for Agriculture Extension presented by the Ontario Agriculture College. FRANÇOIS TARDIF François is a Professor in the Department of Plant Agriculture, University of Guelph. His research programs focus on weed management and weed biology in field crops and turf. One emphasis of his program is the understanding of herbicide resistance in weeds, so as to develop better resistance management strategies. Dr. Tardif received his BSc., MSc. and PhD. from Laval University in Québec City, Québec, Canada, where he specialized in crop production and weed science. After completion of his studies, he went on to work in Adelaide, Australia to specialize in herbicide resistance. Dr. Tardif has been at the University of Guelph since 1996 where he has taught weed science to graduate, undergraduate and diploma students and supervised MSc. and PhD. students. JOCELYNE LETARTE Jocelyne was raised in a small town just outside of Québec City. Surrounded by farmlands, one of Jocelyne’s fondest memories with plants was riding her bike in the early days of summer to look for the best patch of wild strawberries and bring back home her precious harvest to eat with fresh cream and a “soupçon” of maple syrup. Later on, as a young adult, she received a B. Sc. in biochemistry at Laval University and then, decided to pursue graduate studies and obtained her MSc. in biochemistry-immunology at the same university. With a desire to travel, she accepted a PhD. scholarship offer from the University of Adelaide in Australia and earned her doctorate in plant molecular biology. Nowadays, she is still involved in the world of plants and works as a Research Associate at the University of Guelph in the department of Plant Agriculture. Her pleasure of berry picking has never left her and every summer she now brings her daughters and husband in tow for a bit of PYO and fun while exploring Ontario beautiful farmlands. CONTENTS * poisonous species Blueweed 4 Spiny Annual Sow-Thistle 66 Buttercups * 6 Annual Sow-Thistle 68 Poison Ivy * 8 Dandelion70 Carpetweed10 Cocklebur72 Angelica12 Dogbane * 74 Wild Chervil 14 Northern Willowherb 76 Spotted Water-Hemlock * 16 Yellow Evening-Primrose 78 Wild Carrot 18 Corn Speedwell 80 Cow Parsnip * 20 Common Speedwell 82 Giant Hogweed * 22 Bird’s-Eye Speedwell 84 Wild Parsnip * 24 Purslane Speedwell 86 Common Ragweed 26 Common Mullein 88 Giant Ragweed 28 Spreading Atriplex 90 Common Burdock 30 Lamb’s-quarters92 Biennial Wormwood 32 Figleaved Goosefoot Tall Beggarticks 34 Kochia96 Spotted Knapweed 36 Wild Cucumber Ox-Eye Daisy 38 Bur Cucumber 94 98 100 Chicory40 Goldencreeper102 Canada Thistle 42 Field Horsetail * 104 Bull Thistle 44 Scouring Rush * 106 Nodding Thistle 46 Black Medick 108 Annual Fleabane 48 Common Yellow Woodsorrel 110 Canada Fleabane 50 Kudzu112 Prickly Lettuce 52 Tufted Vetch 114 Nipplewort54 Cleavers 116 Scentless Chamomile 56 Smooth Bedstraw 118 Scotch Thistle 58 Velvetleaf 120 Tansy Ragwort * 60 Flower-of-an-hour122 Common Groundsel * 62 Common Mallow 124 Perennial Sow-Thistle 64 Common Milkweed 126 Pokeweed * 190 Hemp-nettle130 Scarlet Pimpernel * 192 Henbit132 Purslane194 Purple Deadnettle 134 Sulphur Cinquefoil 196 Hedge Bindweed 136 Prostrate Knotweed 198 Field Bindweed 138 Wild Buckwheat 200 Garlic Mustard 140 Lady’s Thumb 202 Shepherd’s-Purse 142 Dog Strangling Vine 128 Docks 204 Flixweed144 Three-Seeded Mercury 206 Whitlowgrass 146 Teasel208 Field Peppergrass 148 Field Violet Wild Mustard 150 Quackgrass212 210 Stinkweed152 Wild Oats 214 Jimsonweed * 154 Downy Brome 216 Clammy Ground-Cherry * 156 Chess218 Smooth Ground-Cherry * 158 Long-Spined Sandbur 220 Horse-Nettle * 160 Smooth Crabgrass 222 Eastern Black Nightshade * 162 Large Crabgrass 224 Hairy Nightshade 164 Barnyard Grass 226 Palmer Amaranth 166 Wire-Stemmed Muhly 228 Green Pigweed 168 Witchgrass230 Redroot Pigweed 170 Fall Panicum 232 Waterhemp172 Proso Millet 234 Mouse-Eared Chickweed 174 Bluegrass Species 236 White Cockle 176 Giant Foxtail 238 Night-Flowering Catchfly 178 Yellow Foxtail 240 Bladder Campion 180 Green Foxtail 242 Corn Spurry 182 Yellow Nutsedge 244 Chickweed184 Citations246 Narrow-Leaved Plantain 186 Index250 Broad-Leaved Plantain 188 BLUEWEED Borage (Boraginaceae family) • Echium vulgare L. EPPO Code: EHIVU Other names: viper’s bugloss, blue devil, blue-thistle SPECIES INFORMATION Lifecycle: Biennial to short-lived perennial. Propagation: Reproduces by seed. Emergence: The majority of seeds germinate in the spring although there is some emergence in the fall. Habitat: Blueweed is native to Eurasia. It is found in pastures, and waste areas, and along roadsides. It prefers dry, rocky or sandy, gravelly soils. Competitiveness: No published data exists since this plant is rarely found in cultivated fields. IDENTIFICATION CLUES Seedling Cotyledons: Initially long-oval, they become oblong with hairy margins, 10 mm long. Young leaves: First year plants form a rosette of long, narrow and harshly hairy leaves. Mature leaves: Basal leaves are long and narrow with stalks. Stem leaves are alternate and become smaller moving up the stem. All leaves are covered with stiff hairs, and their undersides are often spotted with dark flecks. Mature plant Stem: Several stems can arise from each taproot. They grow up to one metre in height, are speckled and covered in stiff hairs. Some hair is long with swollen reddish or blackish bases that arise from small bumps, and some hair is short and dense. Flowers: Flowering stems are produced in the second year on short, arching stems that elongate after flowering. Flowers have bright blue petals that are fused at the bases; upper lobes are longer than lower lobes and have a hairy stigma. Its stamens are red. Blueweed flowers from June to September. Roots: Long, thick black taproot Helpful Identification Tip The bright blue flowers of blueweed are showy and attract honeybees. As the plant matures, the stiff hairs on the leaves and stems becomes sharp and hard and can irritate human skin. 4 WEED ID GUIDE FOR ONTARIO CROPS BLUEWEED 2 1 3 1 A second-year plant that is flowering in early July 2 The much-branched hairy stems with several reddish-brown speckles 4 3 The showy blue flowers with red stamens 4 A flowering plant along a roadside in early July WEED ID GUIDE FOR ONTARIO CROPS 5 BUTTERCUPS* (TALL AND CREEPING) Buttercup (Ranunculaceae family) • Ranunculus acris L. and Ranunculus repens L. EPPO Code: RANAC and RANRE respectively * POISONOUS TO LIVESTOCK WHEN CONSUMED SPECIES INFORMATION Lifecycle: Both species are perennial. Propagation: Both species reproduce by seed, while creeping buttercup also reproduces from horizontal stems that root at the nodes. Habitat: The buttercup species are rarely found in cultivated fields. They are most commonly found in meadows, pastures, lawns and waste areas. Toxicity: According to the University of Illinois Veterinary Medicine Library (Buttercup, Ranunculus spp, n.d), pasture grazed livestock are at the biggest risk of poisoning since the leaves of fresh buttercup species contain a bitter juice called protoanemomin which is the toxic component. Dried plants are not considered toxic, so the feeding of dry hay infested with dried buttercup plants is not considered risky. Tall buttercup has been most implicated in cases of livestock poisoning, symptoms of which include colic, diarrhea, laboured breathing, twitching and convulsions. Cattle are more sensitive to buttercup poisoning than other livestock. IDENTIFICATION CLUES We are lumping both common buttercup species together because the main concern of having any buttercup species in agriculture is the potential for livestock poisoning. Therefore, it’s most important to tell the difference between both buttercups only if you wish to attempt management of one of these species through the use of herbicides. There are distinct differences in the leaf structure of both buttercups, but simply put, tall buttercup is much taller than creeping buttercup. 6 WEED ID GUIDE FOR ONTARIO CROPS BUTTERCUPS 1 3 2 4 1 The deeply divided leaf of tall buttercup 2 Tall buttercup’s yellow flower with five petals that are seemingly fused together 3 Creeping buttercup’s leaf with lobed sections 4 Creeping buttercup’s yellow flower with five petals that are distinctly separate 5 A tall buttercup plant hovering above a cluster of creeping buttercup plants 5 WEED ID GUIDE FOR ONTARIO CROPS 7 POISON IVY* Cashew family (Anacardiaceae family) • Toxicodendron radicans (L.) Kuntze EPPO Code: TOXRA * POISONOUS WHEN TOUCHED (ALL PARTS ARE POISONOUS) SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and by woody rhizomes. Emergence: Poison ivy will begin to emerge as soon as the soil warms in spring. Shoots emerge from woody rhizomes. Habitat: The poisonous plant is most commonly found in and around woodlots, but it can also be found in waste areas, and along fence lines and roadsides. Competitiveness: Poison ivy is rarely found in agricultural crops; however, there is potential for the plant to establish in orchard crops. Concern of its existence would be dermatitis caused by contact with the plant’s oily allergen (urushiols). IDENTIFICATION CLUES Stems: The stem of poison ivy is woody and grows in two ways. The most common variety grows horizontally along the ground with upright leafy stalks; the other variety is a climbing vine. Leaves: Everyone knows the “leaves of three, let them be” line, but there are a lot of plants with three leaflets. Focus less on the type of leaf margin and colour, as both vary depending on their environment and the time of year. For example, leaves are generally a copper or reddish colour in the early part of spring, but are bright green in the summer months. If we look at the three leaflets that make up the compound leaf, it is the middle leaflet that we should pay attention to. It exists on a much longer stalk (called a petiole) than the other two leaflets. The compound leaves of poison ivy are oriented alternately on the stem. Both the alternate leaf orientation and the long petiole on the middle leaflet distinguish poison ivy from other three-leaflet plants. Flowers: Poison ivy’s flowers are small and white or greenish with five petals in branching clusters that are often found hidden below its leaves. Flowers turn into whitish to dull greenish-yellow, round, berry-like fruit that contain one seed. Seeds: Its seed appears like two circles fused together. Seeds are less than 5mm and range from dark grey to dark brown in colour. Roots: Small fibrous roots attached to spreading woody rhizomes. OFTEN MISTAKEN FOR I know it’s NOT … because … Virginia creeper … the compound leaf of poison ivy contains three leaflets, whereas the compound leaf of Virginia creeper has five. Manitoba maple … older Manitoba maple leaves have five leaflets, while younger ones have three leaflets. While they are easily confused with poison ivy, they are oppositely oriented along the stem compared with the alternate leaf arrangement of poison ivy. 8 WEED ID GUIDE FOR ONTARIO CROPS POISON IVY 1 2 4 1 Compound leaf with three leaflets, the middle leaflet at the end of a long petiole 3 2 A cluster of plants in a woodlot during August 3 Compound leaves with reddish leaflets 4 The round berry-like fruit of poison ivy WEED ID GUIDE FOR ONTARIO CROPS 9 CARPETWEED Carpetweed (Aizoaceae family) • Mollugo verticillata L. EPPO Code: MOLVE Other Names: mollugo SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seeds. Emergence: Being of tropical origin, carpetweed germinates later than most annual weed species. Habitat: Carpetweed is found mainly on sandy soil, but also across a number of different environments, including in row crops and waste areas. Competitiveness: Because of its prostrate growing habit, it is not very competitive against crops that produce a tall, thick canopy. IDENTIFICATION CLUES Seedling Cotyledons: Oblong, thick and smooth. Young leaves: Young leaves form a basal rosette. They are narrow at the base and become wider towards the rounded apex (tip). Leaves are hairless. Mature leaves: The shape of carpetweed’s mature leaves remain similar to its young leaves, but they are narrower and grow in whorls of 3–8 leaves at each stem node. Mature leaves are also hairless. Mature plant Stems: The weed’s stem is thin, smooth and prostrate. There is much branching, allowing the plant to form carpet-like patches. Flowers: Carpetweed’s flowers are small, five-petal and white. They grow in clusters with 2–5 flowers in the leaf axils. Seeds: The weed’s seeds are flat, kidney shaped and 0.5 mm long. They are orange-red to brown in colour. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Chickweed … carpetweed has mature leaves that are whorled, while chickweed leaves are not whorled. Chickweed’s small, white five-petal flowers are deeply lobed, giving it the appearance of having 10 petals; carpetweed’s flowers have five petals but are without lobes. Purslane … carpetweed has thin green stems and thin flat leaves while purslane has reddish fleshy stems and fleshy leaves. The flowers of purslane are yellow. Petty spurge … because it has no latex when broken which is the case with spurges. 10 WEED ID GUIDE FOR ONTARIO CROPS CARPETWEED 3 1 4 2 1 A flowering plant in late June with its small taproot 2 A mature plant in mid-August 3 A flowering plant in a corn field on sandy soil 4 A close-up of the white five-petal flower WEED ID GUIDE FOR ONTARIO CROPS 11 ANGELICA Carrot or Parsley (Apiaceae family) • Angelica atropurpurea L. EPPO Code: ANKAT Other names: purple angelica, great angelica, angélique SPECIES INFORMATION Lifecycle: Biennial or perennial. Propagation: Reproduces by seed. Range and habitat: Native to Northern Europe and America. Prefers moist soil and partial shade, commonly found along riverbanks, swamps and wet areas. IDENTIFICATION CLUES Leaves Mature leaves: Large, compound leaves with many leaflets . Mature plant Stem: Thick, purple and hollow; has ridges that run lengthwise down the stem resembling celery stalks; contains yellowish oil; grows up to 2.5 m in height. Flowers: White, globe-shaped, flowering heads which are up to 30 cm in diameter; flowers from June to September but may not flower in its first 2–3 years. Helpful tip Angelica has a thick, purplish and hairless stem with white, globe-shaped flowering heads that distinguish it from other “look-a-like” plants, namely giant hogweed. Historically, the stem, oil and leaves of this aromatic plant were used for culinary, medicinal and industrial purposes. Toxicity This plant is not known to be toxic, but can be confused with other plants from the carrot family that are toxic. OFTEN MISTAKEN FOR I know it’s NOT … because … Spotted water-hemlock ... Angelica (up to 2.5 m in height) grows taller than spotted waterhemlock (1–2 m in height). Spotted water-hemlock has flat, umbrella-shaped flowering heads, whereas Angelica's are globe-shaped. Leaf veins of Angelica go to the tips of the teeth rather than to the notches between the teeth as in spotted water-hemlock. Giant hogweed ... Angelica is a smaller plant. Although the stem of angelica can be red/ purple, it is hairless compared to the red/purple and hairy stem of giant hogweed. Angelica’s large compound leaves are comprised of many small leaflets while giant hogweed’s leaf contains 3 large and deeply cut lobes. The flowering umbels of angelica are smaller and globe-shaped, whereas giant hogweed umbels are up to 1m in diameter and are flat or half-moon shaped. 12 WEED ID GUIDE FOR ONTARIO CROPS ANGELICA 1 4 5 1 A compound leaf comprised of many leaflets having sharply toothed margins 2 2 Note the leaf veins go to the tip of the leaf margin teeth, this is one way to differentiate Angelica from other look-a-like species 3 The reddish-green and completely hairless stem of Angelica 4 The round “globe shaped” seedhead that ranges from 6–15 cm in diameter 3 5 The original author of “Ontario Weeds”, Dr. Jack Alex standing beside a patch of Angelica approaching two metres in height WEED ID GUIDE FOR ONTARIO CROPS 13 WILD CHERVIL Carrot or Parsley (Apiaceae family) • Anthriscus sylvestris (L.) Hoffm. EPPO Code : ANRSY Other names : chervil SPECIES INFORMATION Lifecycle: Biennial or short lived perennial. Propagation: Reproduces by seed. Emergence: Cotyledons emerge in late April or early May. Range and habitat: Native to Eurasia, now spreading throughout North America. Grows in moderately disturbed habitats such as ditches, meadows, fields and hedgerows. Prefers wet habits but commonly found in sandy, clay or peaty soils. Competitiveness: Competes with forage crops for nutrients, water and light. Stems are slow to dry and can decrease crop quality. Toxicity: Wild chervil is not poisonous, but can be mistaken for other plants in the carrot family that are very poisonous. IDENTIFICATION CLUES Seedling Cotyledons: Linear-lanceolate, narrowing gradually at the base and lacking distinct leaf stalks. Leaves First leaves: Rosette in the first year, made up of finely divided, fern-like and hairless leaves. Mature leaves: Green, fern-like and nearly hairless; divide into smaller leaflets giving the outline of the entire leaf a triangle-shape; leaf bases surround the stem. Mature plant Stem: Green, usually without purple mottling; often under 1 m in height but varies between 0.5–2 m. Flowers: At the end of each stem; white and umbrella-shaped; small bracts at the base of the simple umbels, but no bract around the base of each of the individual rays; flowers from May to August. Fruit: Smooth and “banana-shaped”. Roots: Thick, tuberous taproots. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild carrot ... Leaves of wild carrot are very fine, “feather-like” and delicate-looking compared to wild chervil leaves. Wild carrot flowers curl upwards after they bloom and smells of carrot. Poison hemlock ... Despite similar umbels of white flowers and finely-divided leaves, wild chervil is a smaller plant and has green leaves and stems without the red-purple mottling that is present on poison hemlock. Sweet cicely ... Although the foliage is similar, sweet cicely has longer, sharply angled seeds and the plant is fragrant when crushed. Goutweed ... Unlike wild chervil, the leaves of goutweed are broader, usually have 3 lobes and are not fern-like in appearance. 14 WEED ID GUIDE FOR ONTARIO CROPS WILD CHERVIL 1 3 2 1 A cluster of bolted plants, originating from second year rosettes and with some having seed heads during the first week of May 4 2 The finely divided wild chervil leaf 3 A flowering plant during the second week of May 4 A mature seed head during the last week in June 5 An infestation of wild chervil along a roadside during the first week of June 5 WEED ID GUIDE FOR ONTARIO CROPS 15 SPOTTED WATER-HEMLOCK* Carrot or Parsley (Apiaceae family) • Cicuta maculata L. EPPO Code: CIUMC Other Names: beaver poison, musquash-root, poison parsnip, spotted hemlock, water hemlock * POISONOUS IF CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and rootstocks. Emergence: Seeds only germinate after immersion in water (Mulligan and Munro, 1990). Habitat: A native species that can be found throughout Ontario, spotted water hemlock is always found near water likely because of its germination requirements. Competitiveness: No data exists on the competitiveness of spotted water hemlock. Presumably, this is because the species is never found in cultivated fields. Toxicity: Spotted water hemlock is considered the most poisonous of all Ontario weeds since it contains a very potent toxin, cicutoxin, that is present in all plant parts. There have been numerous accounts of sickness and death through consumption by both humans and livestock, as reported by Mulligan and Munro (1990). IDENTIFICATION CLUES Leaves Young leaves: Basal leaves are twice compound with many leaflets and have sharply toothed margins. Mature leaves: Mature leaves are similar to basal leaves. The veins of the leaflets go to the notches between the teeth on the margins. Mature plant Stem: Spotted water hemlock’s stem is erect and grows 1–2 m high. It is round or slightly angular with purplish lengthwise streaks. Flowers: Its flowering head is umbrella-shaped, compound and grows up to 12 cm in diameter. The flower is comprised of smaller umbels made of many individual flowers that are white with 4–6 petals. Spotted water hemlock flowers from June to August. Roots: Branched taproot with secondary tuberous roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Cow-parnsip … Cow-parsnip is usually taller, thicker and “wooly” in appearance compared to spotted water-hemlock. Giant hogweed … Giant hogweed is a much larger plant (it can grow to be 4.5 meters tall and has larger flowers) and its compound leaves are not comprised of many leaflets. 16 WEED ID GUIDE FOR ONTARIO CROPS SPOTTED WATER-HEMLOCK 1 2 4 1 A flowering plant that is about 70 cm tall growing along a river during early August 3 2 Compound leaf made up of several leaflets 3 Sharply toothed margins with the veins of the leaflet going to the notches between the teeth on the margins 4 The white, small, clustered and umbrella-shaped flower head WEED ID GUIDE FOR ONTARIO CROPS 17 WILD CARROT Carrot or Parsley (Apiaceae family) • Daucus carota L. EPPO Code : DAUCA Other names : carrot sauvage, bird’s-nest, Queen Anne’s-Lace, carotte SPECIES INFORMATION Lifecycle: Biennial or annual, occasionally a short lived perennial. Propagation: Reproduces by seed only. Emergence: Emerges both in the fall and spring/early summer. Range and habitat: A very ubiquitous weed in Ontario found in landscapes. In cultivated crops it is more commonly found in reduced tilled cropping systems on heavier textured soils. Competitiveness: Presumed to be moderately competitive, however, no crop yield loss values have been published. IDENTIFICATION CLUES Seedling Cotyledons: Linear, relatively long, tapering at the base and at the tip. Leaves First leaves: Green, first few leaves have three main divided segments. Mature leaves: Green and finely divided, hairy, virtually identical to cultivated carrot having the same odour when the leaf tissue is crushed in one’s hand. Typically forms an overwintereing rosette that will bolt and flower the next spring. The plant dies once it has produced seed. Mature plant Stem: Green, round with fairly dense shorty “whisker like” hairs up to 1.2 m high. Flowers: At the end of each stem; white and arranged into umbrella-shaped inflorescence; a whorl of several branched bracts at the base; the centre of umbrella shaped flower will often contain a dark purple flower; typically flowers from June to September; after flowering the mature seed head curls up and looks like a “bird’s-nest”. Fruit/seeds: Greyish brown with spines that cling easily to animal fur and clothing. Seed can be dormant for several years before germinating. Roots: Taproot with a distinct carrot like odour, tastes of carrot but is extremely fibrous and unpalatable. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild chervil ... Leaves of wild carrot are very fine, “feather-like” and delicate-looking compared to wild chervil leaves. Wild carrot flowers much later than wild chervil. Poison hemlock ... Wild carrot, especially the root, will have a distinct carrot odour. The stem of wild carrot is hairy, while poison hemlock’s is smooth with purple speckles. Poison hemlock also flowers much earlier than wild carrot. Goutweed ... Unlike wild carrot, the leaves of goutweed are broader, usually have 3 lobes and are not deeply divided. 18 WEED ID GUIDE FOR ONTARIO CROPS WILD CARROT 1 3 2 4 1 The linear cotyledons of wild carrot 2 A September germinated seedling with its three main divided segments 3 The round stem with several short whisker like hairs 4 A plant in the rosette stage in the fall having germinated in the spring 5 The umbrella shaped and white flowering head taken in late July 5 WEED ID GUIDE FOR ONTARIO CROPS 19 COW PARSNIP* Carrot or Parsley (Apiaceae family) • Heracleum sphondylium ssp. montanum (Schleich. ex Gaudin) Briq. EPPO Code: HERMA Other Names: Indian celery, pushki, common cow parsnip * POISONOUS TO THE TOUCH SPECIES INFORMATION Lifecycle: Mostly biennial, sometimes perennial. Propagation: Reproduces by seed. Emergence: Cow parsnip seedlings mostly germinate in May and June, but they can germinate later in the summer and into the fall. Habitat: Cow parsnip grows throughout Ontario along the edge of moist areas and in meadows. Competitiveness: Cow parsnip is rarely found in field crops and is probably not very competitive. Toxicity: This plant contains the same type of sap that is in giant hogweed which is light activated and causes phytophotodermatitis (skin irritation). If your skin comes into contact with the sap, get out of the sun immediately and wash with soap and water. IDENTIFICATION CLUES Leaves Cotyledons: Oblong First true leaves: Cow parsnip grows a rosette in its first year. The first true leaf is broad, has three lobes and small teeth at the margin. Mature leaves: The leaves of cow parsnip are divided into three segments and appear similar to a maple leaf or an open palm with fingers outstretched. Basal leaves grow on long stalks (up to 1 m high), and are divided into three broad leaflets that are deeply lobed and toothed. The leaves have veins that run to the end of the leaf tips. Stem leaves are similar, only smaller. Mature plant Stem: The stem of cow parsnip is hollow and wooly looking with deep ridges. It can grow 1.5–2.5 m in height. Flowers: Its flowering head is large (up to 20 cm across) and umbrella shaped. Individual flowers, which bloom from June to September, are white and have five petals. Roots: Cow parsnip produces a fleshy taproot in its first year. OFTEN MISTAKEN FOR I know it’s NOT … because … Spotted water hemlock … Cow parsnip is usually taller, thicker and can be “wooly” in appearance compared to spotted water hemlock. Giant hogweed … Giant hogweed has larger flowers and is a much larger plant growing to a height of 4.5 m tall. 20 WEED ID GUIDE FOR ONTARIO CROPS COW PARSNIP 1 3 2 1 The divided, three-segment leaf 2 A flowering plant that stands about 1.5 m tall 4 3 The green and finely hairy stem 4 The white, small, clustered and umbrella-shaped flower head 5 A close-up of the small, white, fivepetalled flowers 5 WEED ID GUIDE FOR ONTARIO CROPS 21 GIANT HOGWEED* Carrot or Parsley (Apiaceae family) • Heracleum mantegazzianum Somm. & Lev. EPPO Code: HERMZ Other Names: hogweed * POISONOUS TO THE TOUCH SPECIES INFORMATION Lifecycle: Short lived perennial, sometimes biennial. Propagation: Reproduces by seed. Emergence: Seedlings germinate in the spring, late summer and early fall. Habitat: Giant hogweed grows throughout Ontario along the edge of moist areas and in meadows. Competitiveness: Traditionally, giant hogweed is not found in field crops as the plant does not thrive in disturbed environments, but it has been creeping into forage and pasture fields that are close to river flats. Toxicity: Sap from giant hogweed’s broken stalks, leaves and flowers can cause phytophotodermatitis (skin irritation) in humans. Symptoms may appear 24–48 hours following contact with sap and are triggered by UV rays (sun exposure); they range from red skin to large blisters that do not spread or itch the way poison ivy rashes do. IDENTIFICATION CLUES Leaves Cotyledons: Elongated and narrowing at the base into a long stalk. Young leaves: Giant hogweed’s first true leaves are round with wavy-toothed margins on hairy, red-speckled petioles (stalks). Mature leaves: Basal rosette leaves are divided into three broad leaflets that are deeply lobed and toothed with veins that run to the top of the leaf tips. On large plants, they can reach up to 1 m wide. Stem leaves appear similar, but smaller. Mature plant Stem: The stem of giant hogweed is covered in reddish-purple speckles and short whisker-like hairs. It is hollow and grows up to 4.5 m tall and 10 cm in diameter. In the early spring giant hogweed will grow as fast as 10 cm/day. Flowers: The flowering head of giant hogweed is umbrella-shaped and 40–60 cm wide, but can be as much as 1.2 m across. Its flowers have white petals. When flower heads are cut to stop the spread of seed, the plant will produce a new flower head within 7–10 days. Giant hogweed flowers from June to August. Seeds: oval and about 10 mm long, yellowish-brown with four prominent brown oil ducts. Roots: Giant hogweed has a taproot that will reach a depths of over 1 m. OFTEN MISTAKEN FOR I know it’s NOT … because … Cow parsnip … Giant hogweed is a much larger plant (it can grow to be 4.5 meters tall and has larger stems, leaves and flowers). Hogweed stems have reddish-purple speckles as compared to the more or less green stem of cow parsnip. 22 WEED ID GUIDE FOR ONTARIO CROPS GIANT HOGWEED 1 3 2 1 A newly emerged seedling plant beside a mature stalk in late August 2 The rosette leaves in late August from a seedling plant that emerged in the spring 4 3 The mature leaves on elongated stems in early June 4 The green stem with reddish-purple speckles, covered in whisker-like hairs 5 Flowering plant in late June standing approximately 3.5 m tall 5 WEED ID GUIDE FOR ONTARIO CROPS 23 WILD PARSNIP* Carrot or Parsley (Apiaceae family) • Pastinaca sativa L. EPPO Code: PAVSA Other Names: yellow parsnip * POISONOUS TO THE TOUCH SPECIES INFORMATION Lifecycle: Biennial Propagation: Reproduces by seed. Emergence: The majority of seedlings emerge in the spring, but a percentage of dispersed seed will germinate in the fall. Habitat: Wild parsnip is native to Eurasia. It is commonly found along fields and roadsides, and pastures in dry to wet soil types. Competitiveness: Wild parsnip is traditionally not found in field crops. Toxicity: The sap from wild parsnip’s broken stalks, leaves and flowers can cause phytophotodermatitis (skin irritation) in humans. Symptoms may appear in the 24– 48 hours following exposure.They range from reddened skin to large blisters that do not spread or itch, as opposed to those caused by poison ivy. IDENTIFICATION CLUES Leaves Cotyledons: Linear to narrow-elliptical, tappering into a short stalk (20-30 mm long). Young leaves: Leaf blades are small and oval to kidney shaped with coarsely toothed margins and long stalks. During the first season, the plants remain as a rosette. Mature leaves: The mature leaves of wild parsnip branch into leaflets with heavily toothed margins. The plant’s stem leaves are alternate, pinnately compound with 2–5 pairs of opposite, sharply toothed, broad leaflets with a diamond-shaped leaflet at the tip. Leaf stalks are broad and completely encircle the stem. Mature plant Stem: Wild parsnip’s stem is erect and grows up to 1.5 m tall. It is branched and hollow, except where leaves meet the stem. Flowers: The flowering branches of wild parsnip grow from the axils of its upper leaves. The flowers are yellow, small, clustered and umbrella-shaped. Each flower contains five petals. Wild parsnip flowers from May to late autumn. Seeds: Its seeds are round in outline, flat and winged. Roots: The plant develops a thick white to yellow taproot during its first season. OFTEN MISTAKEN FOR I know it’s NOT … because … Angelica …wild parsnip has umbrella-shaped, yellow flower heads and a distinct parsnip odour, whereas Angelica has round, white flower heads. 24 WEED ID GUIDE FOR ONTARIO CROPS WILD PARSNIP 1 3 2 4 1 A pinnately compound leaf 2 A greenish-red stem with alternate leaf arrangement 3 The yellow, small, clustered and umbrella-shaped flower head 4 A mature seed head 5 The large taproot of wild parsnip has a strong parsnip odour 5 WEED ID GUIDE FOR ONTARIO CROPS 25 COMMON RAGWEED Composite or Aster (Asteraceae family) • Ambrosia artemisiifolia L. EPPO Code: AMBEL Other names: short ragweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed, unisexual. Emergence: Most seedlings emerge from early spring to early summer. Range and habitat: Most common in southern and central regions of Eastern Canada, establishes in all soil types. Competitiveness: Extremely competitive at high densities. In field crops yield losses can approach 90 percent. Resistance: Populations resistant to Group 2 (e.g. imazethapyr), Group 5 (e.g. atrazine) and Group 9 (e.g. glyphosate) herbicides exist in Ontario. IDENTIFICATION CLUES Leaves Cotyledons: round or orbicular with short petiole and fleshy appearance. Young leaves: first two leaves are divided into 3 lobes. Mature leaves: Opposite leaf orientation, except towards the end of branches where they may be alternate; deeply divided, densely hairy but short hairs. Mature Plant Stem: Erect, hairy and branched; up to 1.5 m in height. Flowers: Male and female flowers exist on separate flower heads. The pollen producing male flowers are most visible and resemble upside down bowls. The seed producing female flowers are below the male flowers and located in the leaf axils. Flowers from August to October. OFTEN MISTAKEN FOR I know it’s NOT … because… Wild carrot … Common ragweed has round cotyledons compared with the extremely narrow cotyledons of wild carrot. The leaves of wild carrot are more finely divided than common ragweed and have a distinctive smell when the plant tissue is crushed. Biennial wormwood … Comparing the leaves of each plant will make their differences obvious. The leaves of common ragweed are hairy and have rounded edges whereas biennial wormwood leaves lack hair and have sharp edges. 26 WEED ID GUIDE FOR ONTARIO CROPS COMMON RAGWEED 1 4 2 5 1 A 2-leaf seedling plant with its round cotyledons and lobed leaves 2 A 6-leaf common ragweed plant with its deeply divided leaves 3 A cluster of common ragweed plants ranging in stages from 2 to 6 nodes (12 leaves) 4 The male pollen producing flowers resembling a line of upside down bowls 5 The seed producing female flower located in the leaf axils 3 WEED ID GUIDE FOR ONTARIO CROPS 27 GIANT RAGWEED Composite or Aster (Asteraceae family) • Ambrosia trifida L. EPPO Code: AMBTR Other names: great ragweed, kinghead, tall ragweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed, unisexual. Emergence: Most seedlings emerge from early spring to early summer. Range and habitat: Most common in southern and central regions of Eastern Canada, establishes in all soil types. Competitiveness: Extremely competitive at high densities. In field crops yield losses can approach 90 percent. Resistance: Populations resistant to Group 9 (e.g. glyphosate) and Group 2 (e.g. Classic) herbicides exist in Ontario. IDENTIFICATION CLUES Leaves Cotyledons: Spoon shaped, thick and oblong, 3-4 times larger than common ragweed. Young leaves: First pair of leaves opposite and without lobes. Stem: Erect, hairy and branched; up to 4 m in height. MATURE PLANT Stem: Erect, hairy and branched; up to 1.5 m in height. Flowers: Male and female flowers exist on separate flower heads. The pollen producing male flowers are most visible and resemble upside down bowls. The seed producing female flowers are below the male flowers and located in the leaf axils. Flowers from August to October. Helpful tip New seedling plants resemble sunflower seedlings. Larger plants are distinguished by its rough feeling leaves with 3-5 distinct lobes and very tall stature. Giant ragweed is a major cause of hay fever from August to September. OFTEN MISTAKEN FOR I know it’s NOT … because … Goldenrod … Goldenrod is a smaller plant, with narrower leaves that lacks lobes and with distinct, bright yellow flower clusters, whereas giant ragweed flowers are in clusters of what look like tiny green round seeds (flowers do not have petals) that are bunched together. 28 WEED ID GUIDE FOR ONTARIO CROPS GIANT RAGWEED 1 3 2 1 A 2-leaf plant with its oblong cotyledons 2 A seedling plant at the 4 -leaf stage 4 3 The 3-lobed mature leaves with toothed leaf margins 4 The pollen producing male flower shown in early August 5 A heavy infestation of giant ragweed in Essex county at the flowering stage 5 WEED ID GUIDE FOR ONTARIO CROPS 29 COMMON BURDOCK Composite or Aster (Asteraceae family) • Arctium minus Bernh. EPPO Code: ARFMI Other names: burdock, burs, clotbur, lesser burdock, wild burdock, wild rhubarb SPECIES INFORMATION Lifecycle: Biennial Propagation: Reproduces by seed. Emergence: Seedlings emerge early in the spring. Range and habitat: Most commonly found around field boundaries but can creep into cultivated fields especially in cropping systems with reduced tillage. Competitiveness: Unknown, but impedes crop establishment and can smother out other vegetation. IDENTIFICATION CLUES Leaves Cotyledons: Oblong with conspicuous veins. Young leaves: In a basal rosette, round to oval shape with wavy margins and prominent veins Mature leaves: Resembling rhubarb but with undersides having white woolly hairs. Mature plant Stem: Erect, 60–180 cm tall, branched, thick, hollow and grooved lengthwise Flowers: round and densely covered with purplish to white hooked bristles, either having one on a short stalk or in clusters at the end of branches; flowers from July to September; when mature are brown and easily break off with the burs clinging to clothing, and animal fur; angular seed is contained within the burs. Similar species Common burdock is a very distinct plant that is rarely confused with any other plants. There is, however, another burdock plant in Ontario called “great burdock.” It is difficult to tell the two species apart at the vegetative stages but at the flowering stages there are two points of differentiation. Firstly, great burdock flowers are typically larger and with a paler colour. Secondly, the flowers of great burdock are less clustered and are at the end of much longer stalks. 30 WEED ID GUIDE FOR ONTARIO CROPS COMMON BURDOCK 3 1 2 1 Common burdock’s oblong cotyledons 2 Once larger leaves emerge, the margins are wavy 4 3 A second year plant in the rosette stage after over-wintering with its rhubarb like leaves and wavy leaf margins 4 A purplish to white and round flower with its hooked bristles 5 The brown burs that attach easily to many things with each holding several (~40) angular seeds 5 WEED ID GUIDE FOR ONTARIO CROPS 31 BIENNIAL WORMWOOD Composite or Aster (Asteraceae family) • Artemisia biennis Willd. EPPO Code: ARTBI Other names: carrot weed SPECIES INFORMATION Lifecycle: Annual or biennial. Propagation: Reproduces by seed. Emergence: Most seedlings emerge from early spring to early summer. Range and habitat: Found throughout Ontario; tolerates wet soils and can survive moderate flooding; more commonly found in cropping systems with reduced tillage. Competitiveness: North Dakota studies have documented yield losses in soybeans as high as 44 percent (Nelson and Kegode, 2006). IDENTIFICATION CLUES Leaves Cotyledons: Oblong-lanceolate. Young leaves: Basal rosette, deeply divided, hairless. Mature leaves: Alternate leaf orientation, deeply divided, hairless. Mature plant Stem: Erect, smooth and hairless; height is variable and will depend on environment but ranges from 10–150 cm. Flowers: The compact inflorescence contains clusters of round yellowish-green flowers and is leafy throughout. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild carrot .... Biennial wormwood has oblong-lanceolate cotyledons compared with the extremely narrow cotyledons of wild carrot. The leaves of wild carrot are more finely divided then biennial wormwood and will smell like carrots when the plant tissue is crushed. Biennial wormwood ... Comparing the leaves of each plant will make their differences obvious. The leaves of common ragweed are hairy and have rounded edges whereas biennial wormwood leaves lack hair and have sharp edges. 32 WEED ID GUIDE FOR ONTARIO CROPS BIENNIAL WORMWOOD 1 4 2 5 1 Young seedling 2 The deeply divided and hairless leaf of biennial wormwood 3 A seedling plant in mid-June, herbicide applications should be made when plants are at this stage or younger 4 Mature plants in soybeans that have escapes herbicide applications 5 A close-up of the compact inflorescence 3 WEED ID GUIDE FOR ONTARIO CROPS 33 TALL BEGGARTICKS Composite or aster (Asteraceae family) • Bidens vulgata Greene EPPO Code: BIDVU Other names: bur-marigold, beggar’s-ticks SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Little information exists on the emergence of tall beggarticks, but spring emergence has been observed in Ontario. Habitat: Tall beggarticks grows mainly in moist areas along roadsides, in meadows and waste places and in depressions in cultivated fields. Competitiveness: No data exits on the competitiveness of tall beggarticks. It is considered a pollinator-friendly plant, since the flowers attract birds and insects. IDENTIFICATION CLUES Leaves Cotyledons: Elongated Young leaves: The young leaves of tall beggarticks have opposite leaf orientation. Compound leaves have three to five lanceolate leaflets with sharp-toothed margins. Mature leaves: The mature leaves of tall beggarticks are similar to its younger leaves, but the upper stem leaves are typically smaller than the basal leaves. Mature plant Stem: Its stem is erect, and branches up to one metre tall. Usually, though, it grows between 30 and 60 cm tall. Flowers: Its inflorescences have a prominent centre comprised of densely packed yellowishgreen disk florets that are surrounded by 10 to 16 thin bracts. Note, though, that tall beggarticks’ flower heads lack the bright yellow “petals” that nodding beggarticks has. OFTEN MISTAKEN FOR I know it’s NOT … because … Nodding beggarticks … tall beggarticks has compound leaves with three or five leaflets while nodding beggarticks has simple leaves with no divisions. Tall beggarticks lacks the prominent yellow “petals” that nodding beggarticks has. 34 WEED ID GUIDE FOR ONTARIO CROPS TALL BEGGARTICKS 1 4 2 5 1 A young seedling with elongated cotyledons 2 A plant in October with compound leaves having 3 or 5 leaflets 3 A close-up of a compound leaf with 5 leaflets 4 A mature plant in late October 5 A close-up of the upper stem leaves with sharply toothed margins 3 WEED ID GUIDE FOR ONTARIO CROPS 35 SPOTTED KNAPWEED Composite or aster (Asteraceae family) • Centaurea maculosa Lam. EPPO Code: CENMA Other Names: knapweed, star thistle SPECIES INFORMATION Lifecycle: Biennial, perennial Propagation: Reproduces by seed. Emergence: Spotted knapweed seeds germinate when soil temperatures are above 7˚ C with peak germination around 22˚ C (Watson and Renney, 1974). Habitat: Spotted knapweed is found throughout Ontario, mainly along roadsides and fence lines. In certain parts of the province, though, particularly in Grey County, it can be found at high levels in pasture fields. Competitiveness: The weed reduces the quality of forage when contaminating pastureland. The plant is not very palatable and its roots exude an allelochemical (Pollock, 2009) that eliminates or reduces growth of other surrounding plants, which allows knapweed to thrive. IDENTIFICATION CLUES Seedling Cotyledons: Ovate to spatulate, short (25 mm) without a petiole. Young leaves: Its first leaves grow in a basal rosette in the first year; compound leaves are pinnately divided. Mature leaves: Stem leaves are alternate, slender and wiry, pinnately divided, and grey-green in colour. Mature plant Stems: Mature spotted knapweed has an erect, much branched stem that grows up to 1.5 m tall. Stems have a grey green colour. Flowers: Its flower heads are round, 3–4 cm in diameter and made up of several slender light purple-magenta “petals” (disk florets) with the outer ones being longer than the central ones. Underneath and attached to the flowering head are distinct bracts, triangular shaped with brown vertical lines and blackish-brown tips and margins with a fine fringe of comb tooth-like bristles. Seeds: The seeds of spotted knapweed are brown, 2 mm long and angled towards the base. They have a moustache-like pappus at the apex. Roots: Woody taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Brown knapweed … the bracts at the base of the showy flowers on brown knapweed are light brown with membrane-like margins, while the margins of spotted knapweed have a fine fringe of comb-tooth-like bristles. 36 WEED ID GUIDE FOR ONTARIO CROPS SPOTTED KNAPWEED 1 4 2 5 1 A patch of spotted knapweed in Dufferin County during late July 2 The irregularly-lobed leaflets of spotted knapweed 3 The distinct triangular bracts of spotted knapweed with its brownish-black tip and margins that have a fine fringe of comb tooth-like bristles 4 A side view of a flower head that is 4 cm in diameter 5 The bracts of brown knapweed, which are light brown with membrane-like margins compared to the margins of spotted knapweed, which have a fine fringe of comb tooth-like bristles 3 WEED ID GUIDE FOR ONTARIO CROPS 37 OX-EYE DAISY Composite or aster (Asteraceae family) • Leucanthemum vulgare Lam. EPPO Code: CHYLE Other names: field daisy, white daisy, whiteweed, poorland flower, marguerite SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and underground rhizomes. Emergence: Seedlings emerge in early spring but also in the fall. Habitat: Ox-eye daisy is commonly found in waste areas, meadows, pastures and lawns, but can be found in cultivated fields, usually on heavier textured soils. IDENTIFICATION CLUES Leaves Cotyledons: Oval and narrowing into a short petiole. Young leaves: The first seedling leaves of ox-eye daisy are spoon-shaped and lobed with shallow wavy teeth. At first, they are opposite, but they then alternate and produce a basal rosette. Mature leaves: Basal rosette leaves are smooth, hairless, spoon shaped, lobed and wavy toothed. Stem leaves are alternate and more sharply toothed. Mature plant Stem: The stem of ox-eye daisy is erect and grows between 20 and 90 cm tall. Flowers: Its flower heads (inflorescences) are daisy-like with yellow centers (disk florets) and 20–30 white, petal-looking ray florets. The flowerhead is 2.5–5 cm in diameter. Root: Ox-eye daisy has shallow fibrous roots with short rhizomes that hold soil quite efficiently. OFTEN MISTAKEN FOR I know it’s NOT … because … Scentless chamomile … Although the flower heads appear similar, ox-eye daisy’s inflorescence will have 20–30 white ray florets. While scentless chamomile has 10–20 ray florets. The leaves of each plant are drastically different; scentless chamomile’s are finely divided, while the leaves of ox-eye daisy are entire or broadly divided. 38 WEED ID GUIDE FOR ONTARIO CROPS OX-EYE DAISY 2 1 3 1 The daisy-like flower with yellow center and 20–30 white ray florets 4 2 An established perennial plant in winter wheat during late May 3 The lobed leaves with shallow toothed margins 4 The dense fibrous root system with short rhizomes that tightly hold soil WEED ID GUIDE FOR ONTARIO CROPS 39 CHICORY Composite or aster (Asteraceae family) • Cichorium intybus L. EPPO Code: CICIN Other Names: blue dairy, blue sailors, coffee-weed, common chicory SPECIES INFORMATION Lifecycle: Biennial, but usually perennial Propagation: Reproduces by seed. Emergence: Since mature seeds lack primary dormancy, they are able to germinate as soon as they leave the plant. Seed will germinate over a wide range of temperatures (5–35˚C). Seed germination, however, is reduced when passed through the digestive tracts of cattle. Habitat: Chicory is largely found along roadsides and in waste areas, although it is occasionally found in minimum-till (no-till) cropping systems within the Golden Horseshoe area of Ontario. Competitiveness: No data exists on chicory’s competitiveness. In fact, more information exists on how to cultivate the plant, as it has been traditionally grown for medicinal purposes as it is rich in inulin, a unique type of dietary fiber. The leaves have been used as a vegetable crop and the roots as a coffee substitute (University of Nebraska-Lincoln, n.d.). More recently, there has been interest in growing it as a forage plant (Hall and Jung, 2008). IDENTIFICATION CLUES Seedling Cotyledons: Oval to club shaped, tapering at the base into a short stalk, slightly indented at the apex. First leaves: Chicory’s first leaves appear as a basal rosette, closely resembling dandelion. They are elongated, wider near the apex and tapering near the base, margins irregularly wavy. Older leaves are rough and hairy compared to the relatively smooth leaves of dandelion. Mature leaves: Stem leaves are alternate and lower leaves will be reminiscent of dandelion leaves; upper stem leaves are triangular and clasping the stem. Mature plant Stems: Chicory’s stem is erect and grows up to 1.5 m tall. It is covered in coarse whisker-like hairs and is much branched. Milky sap will exude from the stem when broken. Flowers: Chicory flowers are bright blue and 3–4 cm in diameter. It is comprised only of petal-like ray florets which are toothed at the apex. Seeds: Its seeds are brown and grow to be 2 mm long. They are roughly triangular in shape, angled towards the base and have a short, bristly pappus at the apex that looks like a moustache. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Dandelion … although it’s almost impossible to tell the difference between dandelion and chicory at the seedling and rosette stage, but as the plants begin the reproductive phase the differences become obvious. . Chicory develops a branched and leafy stem which is absent in dandelion. Chicory has numerous bright blue flowers, and dandelion, with its yellow flowers, is much more common in cultivated fields. 40 WEED ID GUIDE FOR ONTARIO CROPS CHICORY 2 1 3 1 A seedling plant that closely resembles dandelion, but with older leaves that have hair 4 2 A patch of chicory along a roadside in late July 3 Triangular upper leaves that clasp the stem 4 Bright blue flower with apex of ray florets that are toothed WEED ID GUIDE FOR ONTARIO CROPS 41 CANADA THISTLE Composite or aster (Asteraceae family) • Cirsium arvense (L.) Scop. EPPO Code: CIRAR Other Names: Canadian thistle, creeping thistle, field thistle, small-flowered thistle and perennial thistle SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by wind-dispersed seed and by horizontal roots. Emergence: Seed germinates best at higher temperatures (25˚–30˚ C), but will germinate at lower temperatures (10˚ C). Shoot emergence begins as early as April in Ontario and extends into September. Habitat: Canada thistle is relavent in agricultural crops and waste areas. Competitiveness: Canada thistle is a strong competitor. Yield losses above 50 percent have been observed in cereals, soybeans and field corn. IDENTIFICATION CLUES Seedling Cotyledons: Oval, thick and fleshy First leaves: The first leaves on a seedling plant are thick, oval to oblong, and covered with short bristly hairs. Leaf margins have sharp spines and are wavy-toothed. When new leaves emerge as shoots from the horizontal roots they are more irregularly toothed and have sharp spiny margins. Mature leaves: The mature leaves of Canada thistle are irregularly toothed (or lobed) and have very sharp spines along the leaf margins. Mature plant Stems: Canada thistle’s stem is erect, branched and generally smooth, although it can be slightly hairy. Flowers: Generally, Canada thistle flowers from June to August. Each plant has numerous pinkpurple flower heads that can range from 5–20 mm in diameter. Seeds: The seed, which is brown and 2–4 mm long, is enclosed in the fruit (achene) and attached to a white feathery pappus, often referred to as “fluff”. The achene sometimes detaches from the pappus relatively close to the mother plant. Roots: This species has extensive system of creeping roots that are functionally similar to rhizomes. Roots haves been reported to grow consistently below depths of 2 m and horizontally more than 4 m. OFTEN MISTAKEN FOR I know it’s NOT … because … Bull thistle … the leaves of Canada thistle are lighter green in colour and relatively hairless in comparison to the dark green and very wooly leaves of bull thistle. The flower head of bull thistle is three times as large as that of Canada thistle. Nodding thistle … the leaves of nodding thistle are more deeply lobed and have more spines. The flower head of nodding thistle is three to four times larger than that of Canada thistle. While nodding thistle’s flower head will eventually nod towards the ground, Canada thistle’s will stay upright. 42 WEED ID GUIDE FOR ONTARIO CROPS CANADA THISTLE 4 1 5 2 1 A seedling plant with thick and oval cotyledons 2 A leafy shoot emerging from the spreading rhizome in late May 3 A pre-flowering plant in late June 4 A close up of the small pinkishpurple flower heads 5 A mature seed-head with the white feathery pappus that most refer to as “fluff” 3 WEED ID GUIDE FOR ONTARIO CROPS 43 BULL THISTLE Composite or aster (Asteraceae family) • Cirsium vulgare (Savi) Tenore EPPO Code: CIRVU Other Names: spear thistle SPECIES INFORMATION Lifecycle: Biennial Propagation: Reproduces by seed. Emergence: Seeds germinate in both the fall and spring. Habitat: Bull thistle is found everywhere in Ontario. In agricultural landscapes, it is most commonly found along fence lines and roadsides, and in pastures and waste areas. Competitiveness: The main concern with bull thistle is that it is not palatable to most types of livestock, with the exception of goats. IDENTIFICATION CLUES Seedling Cotyledons: Egg-shaped to almost round, fleshy with a short stalk, 8 to 15 mm long. Young leaves: Bull thistle’s first leaves are oval with a fringe of spines, and dark green with dense, white hairs on the under surface. Mature leaves: Its rosette leaves are dark green; the upper and lower surfaces are covered in dense, white hairs. Margins are deeply lobed with sharp spines at the tip of each lobe. Mature plant Stems: Bull thistle’s stem is erect and branched with a mix of sharp spines and dense white hairs. It is green to greenish-red in colour. Flowers: The flower heads are round to pear shaped; florets are bright purple and come out at the top. Below the florets there are several spiny bracts. Roots: In its first year, a taproot forms. In its second year, a secondary fibrous root system will typically form. OFTEN MISTAKEN FOR I know it’s NOT … because … Canada thistle … the leaves of Canada thistle are lighter green in colour and relatively hairless in comparison to the dark green and very wooly leaves of bull thistle. The flower head of bull thistle is three times as large as that of Canada thistle. Nodding thistle … the leaves of nodding thistle are more deeply lobed, bright green and lack the white surface hairs that appear on the dark green leaves of bull thistle. Although the flower heads of each species appear similar, nodding thistle’s flower head will eventually nod towards the ground, while bull thistle’s will stay upright. 44 WEED ID GUIDE FOR ONTARIO CROPS BULL THISTLE 1 3 2 1 A seedling rosette in autumn 2 An established second year rosette with dark green leaves, fuzzy surface and spiny margins 4 3 The erect, branched and spiny stem 4 The showy bright purple florets with spiny bracts underneath 5 A mature plant 5 WEED ID GUIDE FOR ONTARIO CROPS 45 NODDING THISTLE Composite or aster (Asteraceae family) • Carduus nutans L. EPPO Code: CRUNU Other Names: musk thistle SPECIES INFORMATION Lifecycle: Biennial Propagation: Reproduces by wind-dispersed seed. Emergence: Seed germinates in the fall and in the spring. Habitat: Nodding thistle is found primarily in pastures and waste places, and along roadsides. It is rarely found in cultivated crops. Competitiveness: Nodding thistle reduces the productivity of pastures because it is largely unpalatable to many livestock. IDENTIFICATION CLUES Seedling Cotyledons: Oblong with no petiole and a prominent white vein. Young leaves: Its first leaves are bright green with lobed margins that have sharp spines that point in all directions. Mature leaves: Similar to its rosette (young) leaves, but smaller, the mature leaves are less lobed and alternately oriented on the stem. Mature plant Stems: Hairy and with sharp spines. Flowers: Generally, nodding thistle flowers from June to October. Each plant has numerous bright purple flower heads that can range from 3–5 cm in diameter. Flowers will “nod” to one side. Seeds: The seed, which is light brown, shiny and 4 mm long with a knob at the end, is attached to a white feathery pappus, often referred to as “fluff”. The seed, which is light brown, shiny and 4 mm long has a knob at the tip; a long white feathery pappus, often referred to as “fluff”, is attached at the tip but falls easily. Roots: Thick, long and fleshy taproot. OFTEN MISTAKEN FOR I know it’s NOT … because … Bull thistle … the leaves of nodding thistle are lighter green in colour and the lobes are much closer together. The flower head of nodding thistle tends to droop down or “nods” to the ground, whereas bull thistle’s flower head is more upright. Canada thistle … the leaves of nodding thistle are more deeply lobed and have more spines. The flower head of nodding thistle is three to four times larger than that of Canada thistle. While nodding thistle’s flower head will eventually nod towards the ground, Canada thistle’s will stay upright. 46 WEED ID GUIDE FOR ONTARIO CROPS NODDING THISTLE 1 4 2 5 1 A rosette with bright green, lobed margins with sharp spines 2 A close-up of sharp spines on leaf margins 3 The hairy stem with sharp spines 4 A flowering plant in mid-August 5 The bright purple flowers along with mature seed heads with white “fluff” 3 WEED ID GUIDE FOR ONTARIO CROPS 47 ANNUAL FLEABANE Composite or aster (Asteraceae family) • Erigeron annuus (L.) Pers. EPPO Code: ERIAN Other Names: daisy fleabane SPECIES INFORMATION Lifecycle: Annual or sometimes biennial. Propagation: Reproduces by seed. Emergence: No information exists on the germination pattern of annual fleabane in Ontario, but seedlings have been observed in both the spring and fall. Habitat: Annual fleabane is native to North America and found in sunny areas, and in sand and clay soils. It is also found in waste areas and pastures, and along roadsides. Most often, though, it is found in cereal and forage crops. It is found infrequently in corn and soybeans. Competitiveness: No data exits on the competitiveness of annual fleabane, however, one can assume that it is similar to that of Canada fleabane. It should be noted however that this weed is rarely a problem in cultivated crops and is considered a “pollinator-friendly” plant species. IDENTIFICATION CLUES Seedling Cotyledons: Round, hairy. Young leaves: Annual fleabane grows in a basal rosette. Its leaves are broad, coarsely toothed, longstalked, bright green and usually hairy. Mature leaves: Mature leaves have alternate leaf orientation. The lower and middle stem leaves are narrower than first leaves, soft and hairy, and usually do not clasp the stem. Its upper leaves are short stalked or stalk-less. Sometimes they partially clasp the stem and are smooth in outline or have shallow grooves. Mature plant Stem: Annual fleabane’s stem is simple, although it can branch further up the stem. Its stem is short, has white hairs and grows up to 1.5 m tall. Flowers: Its inflorescences grow in clusters at the ends of branches. They appear “daisy-like,” but are smaller and more densely packed. Ray florets are white (and sometimes pinkish) while disk florets are yellow. Fruit: Seeds are contained in small fruit (1mm); fruit are light brown in colour and have small hairs (pappus) that aid in dispersal. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Philadelphia fleabane … The flower heads of Philadelphia fleabane are similar to annual fleabane in shape and size, but are usually pink to purple in colour. Its upper leaves are broader and strongly clasp the stem. Canada fleabane … Canada fleabane has narrower and darker green leaves with margins that are generally less toothy. Annual fleabane has larger and broader leaves and showy “daisy-like” flowers. 48 WEED ID GUIDE FOR ONTARIO CROPS ANNUAL FLEABANE 1 4 5 1 A seedling plant in mid-May 2 2 A side view of the seedling plant with alternate leaves and hairy stem 3 The upper stem leaves with toothed margins 4 A cluster of annual fleabane’s white, “daisy-like” inflorescences in late June 5 A cereal field with annual fleabane and the more pinkish flowered Philadelphia fleabane during late June 3 WEED ID GUIDE FOR ONTARIO CROPS 49 CANADA FLEABANE Composite or Aster (Asteraceae family) • Conyza canadensis (L.) Cronq. EPPO Code: ERICA Other names: bitterweed, fleabane, hogweed, horseweed, mare’s-tail SPECIES INFORMATION Lifecycle: Annual or winter annual. Propagation: Reproduces by seed; the wind dispersed seed can travel several hundred metres from the source plant. Emergence: The majority of seeds will germinate from August to November while the remainder do so in early spring. Range and habitat: Found throughout Ontario; more commonly found in cropping systems with reduced tillage, but also in pastures, roadsides and gardens. Competitiveness: Yield losses in soybeans have been as high as 90 percent with plant densities at 400,000/ac. Resistance: Populations exist that are resistant to Group 9 herbicides (e.g. glyphosate) and Group 2 herbicides (e.g. cloransulam-methyl). IDENTIFICATION CLUES Leaves Cotyledons: oblong Young leaves: round to oval, extremely hairy and with entire margins; fall germinated plants will form a basal rosette while spring germinated plants typically skip the rosette stage and bolt. Mature leaves: Alternate leaf orientation, very hairy, toothed leaf margins. Mature plant Stem: Erect, hairy, branched and can be as high as 2 m. Flowers: Small, white on many short branches, clustered at the top. Flowers from late July to late autumn. Seeds are contained in very small brown fruit bearing a fluffy pappus that aids in wind dispersal. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because… Goldenrod … The leaves of Canada fleabane are extremely hairy compared to the relatively hairless leaves of goldenrod. The leaf margins of goldenrod are more sharply toothed then Canada fleabane. Goldenrod has rhizomes compared with Canada fleabane’s taproot. Annual fleabane … The leaves of annual or rough fleabane are much broader, more coarsely toothed and are usually lighter green. The flowers of annual or rough fleabane are much different than Canada fleabane, resembling a daisy flower, although much smaller. 50 WEED ID GUIDE FOR ONTARIO CROPS CANADA FLEABANE 1 3 2 4 1 An over-wintered rosette in winter wheat during late April 2 Canada fleabane is a hairy plant, the older leaves can look like goldenrod but have very hairy margins as shown 3 An early September germinated seedling rosette (15 cm in diameter) during late October 4 The small, white and much branched flowers of Canada fleabane 5 The fluffy mature seeds that are ready for wind dispersal 5 WEED ID GUIDE FOR ONTARIO CROPS 51 PRICKLY LETTUCE Composite or aster (Asteraceae family) • Lactuca serriola L. EPPO Code: LACSE Other Names: wild lettuce, compass plant SPECIES INFORMATION Lifecycle: Winter annual, annual or biennial Propagation: Reproduces by seed. Emergence: The majority of seeds will germinate in autumn with seedling plants often in the rosette stage in the spring. Habitat: Prevalent throughout the province in waste areas, pastures and roadsides and in agricultural crops under minimum till or no-till cropping systems. Competitiveness: Ontario studies have shown yield losses as high as 80% when no-till soybean was competing with prickly lettuce at a density of 50 plants/m2 while no yield losses in winter wheat were observed even though prickly lettuce densities were as high as 200 plants/m2 (Weaver et al., 2006). IDENTIFICATION CLUES Seedling Cotyledons: Rounded and tapering to the base. First leaves: A basal rosette with club-shaped leaves having finely-toothed margins. Mature leaves: alternate orientation on the stem, variable in size and shape ranging from deeply lobed to without lobes but having spiny toothed margins and a prominent single row of stiff, sharp prickles on the midrib of the leaf’s underside; exudes a milky white juice (latex) when broken. Mature plant Stems: Erect, hollow and hairless; ranging from 30-150 cm tall; green to reddish-green; exudes latex when broken. Flowers: Flower heads are made of yellow ray florets and are 8 to 10 mm in diameter; the flower heads are borne at the end of long fine stalks and arranged in a pyramidal panicle. Seeds: Yellowish-brown to brown, 2–4 mm long with prominent ribs on each side and attached to a white feathery pappus that most refer to as “fluff”. Roots: Fleshy taproot. OFTEN MISTAKEN FOR I know it’s NOT … because … Annual or perennial sow-thistle … prickly lettuce’s mature leaves have a row of spines on the underside of its leaf midrib 52 WEED ID GUIDE FOR ONTARIO CROPS PRICKLY LETTUCE 1 4 2 5 1 A fall germinated seedling rosette in late April 2 A spring germinated plant in June 3 The distinct row of spines on the central vein of the leaf underside 4 A pre-bloom plant in winter wheat during late June 5 The small yellow flowers of prickly lettuce 3 WEED ID GUIDE FOR ONTARIO CROPS 53 NIPPLEWORT Composite or aster (Asteraceae family) • Lapsana communis L. EPPO Code: LAPCO Other names: common nipplewort, dock cress, nippleweed SPECIES INFORMATION Lifecycle: Annual or winter annual Propagation: Reproduces by seed Emergence: Emerges in the spring and in autumn Range and habitat: Nipplewort is common throughout Europe, but is now becoming more prominent in Ontario, especially in no-till fields. The plant prefers sun to partial shade and moist to dry, gravelly soil. It is commonly found along rivers and roadsides, and in cultivated fields and disturbed areas. Competitiveness: Little information exists on the competitiveness of nipplewort, but a Norwegian study has identified it as a contributor to yield losses in carrots. (Fiveland, 1974) IDENTIFICATION CLUES Leaves Cotyledons: Round or spoon shaped and covered in soft, white hairs. Young leaves: Rosette of thin, green leaves that are elongated with a rounded terminal lobe and 1–4 side lobes. Mature leaves: Leaves have one large lobe at the tip and various shaped smaller lobes below. Leaves on the upper stem are more narrow and pointed and lack the basal lobes. Mature Plant Stem: Central stem is erect, often red to green, hollow, much branched, and covered with hairs in the lower part of the plant. Flowers: Nipplewort has many branches containing 8–15 yellow flower heads that open from nipple-shaped buds. The inflorescences are dime sized and resemble miniature dandelions with ray florets that have serrated tips. Nipplewort flowers between June and September. OFTEN MISTAKEN FOR I know it’s NOT … because… Sow-thistle species … sow-thistles have soft-spiny to spiny leaf margins, while the leaves of nipplewort have not. Sow-thistle seeds have fluffy white hairs, while nipplewort seeds are free of hair. Prickly lettuce … nipplewort does not have the row of spines that is found on the underside of prickly lettuce leaves. Prickly lettuce seeds have fluffy, white hairs, while nipplewort seeds are free of hair. 54 WEED ID GUIDE FOR ONTARIO CROPS NIPPLEWORT 1 3 2 4 1 A spring-emerged seedling in late June 2 A fall-emerged plant that is flowering in late June 3 The older, lobed basal leaves (left) in contrast to the upper leaves (right) 4 Side view of a flowering plant 5 Close up of the small, round and yellow flower heads with ray florets that have serrated tips 5 WEED ID GUIDE FOR ONTARIO CROPS 55 SCENTLESS CHAMOMILE Composite or Aster (Asteraceae family) • Tripleurospermum inodorum (L.) Sch. Bip. EPPO Code: MATIN Other names: scentless mayweed SPECIES INFORMATION Lifecycle: Short lived perennial but occasionally an annual or biennial. Propagation: Reproduces by seed (achene) only. Emergence: Peak emergence has typically been October, with significant emergence also in April, May and August. Range and habitat: Most commonly found in the Golden horseshoe area of Ontario but has been documented in southern, central and eastern Ontario. Competitiveness: Considered highly competitive and significantly reduces crop harvesting efficiency. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular to oblong. Leaves First leaves: Green, deeply divided into 4 or 5 segments Mature leaves: Green, finely divided, hairless and odourless. Plants will usually form a rosette. Mature plant Stem: Green, hairless, but can be reddish/green at the base Flowers: Daisy like flower head; yellow centered, tubular with white ray florets. Flowers in the summer months. Fruit/seeds: dark brown, 1–2 mm long, 0.5–1 mm wide Roots: A dense fibrous root system that firmly anchors the plant to the ground OFTEN MISTAKEN FOR I know it’s NOT … because … Stinking mayweed … Scentless chamomile lacks any odour when the leaf tissue is crushed, and the leaves are hairless while stinking mayweed has slightly hairy leaves. Pineappleweed … Scentless chamomile lacks any odour when the leaf tissue is crushed compared with a pineapple like odour of pineappleweed. Scentless chamomile has white florets on its flowering head, pineapple weed does not. Ox-eye daisy … The leaves are dramatically different with scentless chamomiles being finely divided compared to the broadly divided ox-eye daisy. 56 WEED ID GUIDE FOR ONTARIO CROPS SCENTLESS CHAMOMILE 1 3 2 4 1 A seedling plant in early June 2 A seedling plant with its orbicular cotyledon and deeply divided leaves with 4–5 segments 3 An infestation of scentless chamomile in Haldimand county in early July 4 The yellow centered flower head with white florets 5 The fibrous root system that holds soil extremely well 5` WEED ID GUIDE FOR ONTARIO CROPS 57 SCOTCH THISTLE Composite or aster (Asteraceae family) • Onopordum acanthium L. EPPO Code: ONRAC Other Names: white thistle, cotton thistle SPECIES INFORMATION Lifecycle: Biennial, sometimes annual Propagation: Reproduces by wind-dispersed seed Emergence: Scotch thistle seed germinates in the spring and late summer. Habitat: The weed is found primarily in pastures, roadsides and waste places. It is rarely found in cultivated crops. Competitiveness: Scotch thistle reduces productivity in pastures as livestock avoid it. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular (round) to oval with whitish veins, tapering into a stalk, approx. 30 mm long. Young leaves: Its first leaves are lanceolate, white and woolly, lobed or coarsely toothed, and have spiny margins. Mature leaves: The mature leaves are similar to the rosette (first) leaves; however, they are smaller and alternately oriented on the stem. Mature plant Stems: Erect, tall (1–2 m), white and woolly with broad and spiny wings. Flowers: The inflorescences are similar to those of bull thistle, but the spiny region below the purple florets is white and wooly. Seeds: The seed, which is light brownish-gray, is 5 mm long and attached to a white feathery pappus, often referred to as “fluff.” Roots: Thick, long and fleshy taproot Note of interest Humans have utilized the plant in many ways, both as food and for medicinal purposes. OFTEN MISTAKEN FOR I know it’s NOT … because … Bull thistle … the leaves and stem of Scotch thistle have a white and wooly appearance, while bull thistle has dark green leaves and a dark green stem. 58 WEED ID GUIDE FOR ONTARIO CROPS SCOTCH THISTLE 1 3 2 4 1 A bolting, pre-flowering plant in early June 2 The coarse toothed and spiny margins of the white/wooly leaf 3 Plants are typically 1–2 m tall 4 A flowering plant in mid-June 5 A close-up of the spiny flowering head just prior to the emergence of its showy purple florets 5 WEED ID GUIDE FOR ONTARIO CROPS 59 TANSY RAGWORT* Composite or aster (Asteraceae family) • Jacobaea vulgaris Gaertn. EPPO Code: SENJA Other names: stinking willie * POISONOUS TO LIVESTOCK WHEN CONSUMED SPECIES INFORMATION Lifecycle: Biennial or short lived perennial. Propagation: Tansy ragwort reproduces by seed and laterally spreading secondary roots. Emergence: Most seedlings emerge from early spring to early summer. Habitat: Tansy ragwort is found predominantly in pastures and waste areas in localized areas throughout Southern Ontario. Toxicity: Tansy is poisonous to livestock and can cause liver damage. Symptoms that may occur after plant consumption include: weakness, high temperature, incoordination and yellow mucous membranes. Currently, there is no known antidote for this alkaloid-based toxin (Lawlis, 1998). IDENTIFICATION CLUES Leaves Cotyledons: Round Young leaves: The first seedling leaves of tansy ragwort are round with entire to wavy margins, but subsequent leaves are more finely divided. Mature leaves: Mature leaves grow in a basal rosette ranging from wavy margined to finely divided leaves that somewhat resemble the leaves of kale. Stem leaves are alternate and finely divided. Mature plant Stem: Tansy ragwort’s stem is erect and covered in cobweb like hairs. The plant grows as tall as 1m. Flowers: Tansy ragwort produces clusters of yellow flower heads with an orange center (disk florets). The center is surrounded by several thin, yellow ray florets (similar to petals) that are pointed to round at the tip. Root: This species produces a short taproot with many lateral secondary roots that can propagate new plants. OFTEN MISTAKEN FOR I know it’s NOT … because … Tansy … the leaves of tansy ragwort do not have an odour reminiscent of mentholated ointment (e.g. Vick’s VapoRub) and the flower heads of tansy do not have petal-like ray florets. 60 WEED ID GUIDE FOR ONTARIO CROPS TANSY RAGWORT 3 1 2 1 A rosette plant with wavy margins and finely divided leaves 2 A large, pre-bolting plant in early June 4 3 The alternate leaf orientation on the stem covered in cobweb-like hairs 4 The distinct flower heads with yellow ray florets and orange prominent centers 5 Tansy ragwort in a pasture field along a fence line 5 WEED ID GUIDE FOR ONTARIO CROPS 61 COMMON GROUNDSEL* Composite or aster (Asteraceae family) • Senecio vulgaris L. EPPO Code: SENVU Other names: groundsel, chickenweed, grimsel, simson, bird-seed, ragwort * POISONOUS TO LIVESTOCK WHEN CONSUMED SPECIES INFORMATION Lifecycle: Annual or winter annual Propagation: Reproduces by seed Emergence: Most seedlings emerge in the spring and fall. Range and habitat: Common groundsel is found throughout Ontario. It is most commonly found in cultivated crops, such as strawberries. It can be troublesome in container-grown and field nursery crops and can also be seen in flower beds and road sides. Toxicity: Ingestion of common groundsel by livestock can lead to liver disease with symptoms including weight loss and weakness that can take several weeks to develop. Poisoning is related to consumption, and cattle, horses and swine are more sensitive to poisoning than sheep and goats that can consume twice the amount before seeing symptoms (Robinson et al., 2003). IDENTIFICATION CLUES Leaves Cotyledons: Oval or club-shaped tapering into a short stalk. Young leaves: The young leaves of common groundsel are round to egg shaped. They have a smooth surface with wavy to finely toothed margins. Mature leaves: Mature leaves are alternate and vary from shallow to deeply lobed. They, too, are smooth, although they sometimes have sparse hairs on the leaf’s surface. Margins are toothed. Mature plant Stem: The stem of common groundsel is erect and grows between 10 and 60 cm in height. Flowers: Clusters of cylindrical flower heads that contain only yellow disk-floret are borne at the end of the stems. The green involucral bracts (below the yellow disk florets) have a distinct black tip. Fruit: Common groundsel produces a red-brown to gray-brown fruit that is 2–4 mm long. It is vertically ridged and attached to a white fluff (called a pappus), which allows seed dispersal via wind. Root: Short taproot with secondary fibrous roots OFTEN MISTAKEN FOR We could be wrong, but rarely is this species confused with others, especially when flowering where it has its distinct black tipped bracts underneath the cylindrical yellow flowers. 62 WEED ID GUIDE FOR ONTARIO CROPS COMMON GROUNDSEL 1 3 4 1 A seedling with elongated cotyledons 2 2 A close-up of the deeply lobed leaves 3 A flowering plant in a strawberry field during early July 4 Close-up of the flowering head during early July WEED ID GUIDE FOR ONTARIO CROPS 63 PERENNIAL SOW-THISTLE Composite or aster (Asteraceae family) • Sonchus arvensis L. EPPO Code: SONAR Other Names: creeping sow-thistle, field sow-thistle, milk thistle, sow-thistle SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and spreads by horizontal roots. Emergence: Shoots emerge in late April to early May. The seed tends to germinate in late May as soil temperatures warm. Habitat: Perennial sow-thistle is very widespread in the province and can be found in waste places, road sides, gardens, lawns and in cultivated fields, especially under reduced tillage. Competitiveness: Perennial sow-thistle is extremely competitive. Where dense patches of perennial sow-thistle exist there is often little crop to harvest. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular First leaves: The first leaves appear as a basal rosette; the leaves are oval to elongated with irregularly toothed margins. Mature leaves: The mature leaves of perennial sow-thistle are elongated, wavy toothed to deeply divided and have spiny margins and a prominent white central vein. Vegetative shoots: While shoots arise in clusters from root buds, the leaf shape will vary from elongated to deeply-divided. Mature plant Stems: Its stem is erect and hollow. It is hairless at the base, but hairy as you go up the stem. Flowers: The flower heads are yellow, 2.5–4 cm in diameter and similar in appearance to those of dandelion as they contain only ray florets. The flowering head’s bracts are densely glandular and hairy. Seeds: Its seeds are brown, 2.5–3.5 mm in length and have five or more prominent ribs on each side. The seeds are attached to a white feathery pappus that most refer to as “fluff”. Roots: Thick, spreading horizontal roots that help in spreading patches. Identification Tip: If parts of the plant are broken, it will excrete a sticky white juice (latex). OFTEN MISTAKEN FOR I know it’s NOT … because … Prickly lettuce … perennial sow-thistle has spreading horizontal roots and lacks the row of spines on the underside of its leaf midrib. Annual sow-thistle … perennial sow-thistle has spreading horizontal roots and flowering heads with densely hairy bracts. It lacks the pointed basal leaf lobes of annual sow-thistle. Spiny annual sow-thistle… perennial sow-thistle has spreading horizontal roots and flowering heads with densely hairy bracts. It also lacks the rounded basal leaf lobes of spiny annual sow-thistle. 64 WEED ID GUIDE FOR ONTARIO CROPS PERENNIAL SOW-THISTLE 1 3 2 4 1 Elongated leaves arising from roots in early May 2 Elongated leaves with margins ranging from wavy toothed to deeply divided 3 White sticky latex exudes from the plant when tissue is broken 4 The densely hairy bracts of perennial sow-thistle’s flower head 5 Perennial sow-thistle’s bright yellow flower head 5 WEED ID GUIDE FOR ONTARIO CROPS 65 SPINY ANNUAL SOW-THISTLE Composite or aster (Asteraceae family) • Sonchus asper (L.) Hill EPPO Code: SONAS Other Names: prickly annual sow-thistle SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: The majority of seed germinates and emerges in mid to late May as soil temperatures warm, but emergence has been observed throughout the season. Habitat: Spiny annual sow-thistle is prevalent in agricultural crops and waste areas where soil has been disturbed. Competitiveness: Crop yield loss depends on the density of spiny annual sow-thistle, but due to its wind-borne seed, this species can quickly become densely populated. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular First leaves: Spiny annual sow-thistle’s first leaves appear as a basal rosette with rounded oval to elongated leaves with wavy toothed margins. It is difficult to differentiate them from annual sow-thistle seedlings. Mature leaves: Mature leaves feel waxy and taper to a pointed tip. They have very spiny margins and two rounded lobes at the base that clasp the stem. Mature plant Stems: Spiny annual sow-thistle’s stem is erect, hollow and hairless. Flowers: Its flower heads are yellow and look similar to those of dandelion as they contain only ray florets. They grow to 1.5–2.5 cm in diameter. The flowering head’s bracts are sparsely haired to hairless. Seeds: The plant’s seeds are brown in colour. They grow to be 2–4 mm long and have 3–5 (or more) prominent ribs on each side. The seeds are attached to a white feathery pappus that most refer to as “fluff”. Roots: Fleshy taproot. Identification Tip The plant will excrete a sticky white juice when parts of it are broken. OFTEN MISTAKEN FOR I know it’s NOT … because … Prickly lettuce … spiny annual sow-thistle lacks the row of spines on the underside of its leaf midrib. Perennial sow-thistle … spiny annual sow-thistle does not have spreading rhizomes, and its flowering heads have hairless bracts. Annual sow-thistle … the leaf of spiny annual sow-thistle has a waxy surface, is very prickly or spiny when you run your hand along the leaf margins and it clasps the stem with round lobes. 66 WEED ID GUIDE FOR ONTARIO CROPS SPINY ANNUAL SOW-THISTLE 1 4 2 5 1 A seedling plant with orbicular cotyledon; the appearance of all seedling sow-thistles are identical 2 As the plant grows, older leaves will have the characteristic waxy surface with coarse spiny margins 3 Mature leaves with their tapered point. Note how they lack the arrow-head leaf apex that annual sow-thistle has 4 Mature leaves clasping the stem with its rounded lobes 5 The mature flower head with pappus (white fluff) and hairless bracts 3 WEED ID GUIDE FOR ONTARIO CROPS 67 ANNUAL SOW-THISTLE Composite or aster (Asteraceae family) • Sonchus oleraceus L. EPPO Code: SONOL Other Names: common annual sow-thistle, hare’s lettuce, colewort, milk thistle SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: The majority of seeds germinate and emerge in mid to late May as soil temperatures warm, but emergence has been observed throughout the season. Habitat: Annual sow-thistle is prevalent in agricultural crops and waste areas where soil has been disturbed. Competitiveness: Crop yield loss depends on the density of annual sow-thistle, but due to its windborne seed it can quickly become densely populated. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular First leaves: The first leaves of annual sow-thistle appear in a basal rosette with rounded, oval to elongated leaves with wavy-toothed margins. The leaf tip starts out rounded, but later has the characteristic triangular or arrowhead-shaped tip. Mature leaves: Mature leaves are elongated and deeply divided with a triangular or arrowhead-shaped tip. The margin is soft-spiny. There are two angular or pojnted lobes at the base that clasp the stem. Leaves appear in an alternate arrangement on the stem. Mature plant Stems: Erect and hollow, annual sow-thistle’s stem is hairless at the base. As you go up the stem, though, it becomes hairy at the top. Flowers: The flower heads of annual sow-thistle are yellow, 1.5–2.5 cm in diameter and similar in appearance to those of dandelion as they are composed only of ray florets. The flowering head’s bracts are sparsely hairy to hairless. Seeds: The plant’s seeds are brown and 2–4 mm long with 3–5 or more prominent ribs on each side. The seeds are attached to a white feathery pappus that most refer to as “fluff”. Roots: Fleshy taproot Identification Tip: The plant will excrete a sticky white juice (latex) when parts of it are broken. OFTEN MISTAKEN FOR I know it’s NOT … because … Prickly lettuce … annual sow-thistle lacks the row of spines on the underside of its leaf midrib. Perennial sow-thistle … annual sow-thistle does not have spreading rhizomes, its leaf tips are triangular or arrowhead shaped and its flowering heads have hairless bracts. Spiny annual sow-thistle … annual sow-thistle lacks the rounded basal leaf lobes of spiny annual sow-thistle. Its leaves do not have a waxy feel to them nor are the leaf margins as prickly as those of spiny annual sow-thistle. 68 WEED ID GUIDE FOR ONTARIO CROPS ANNUAL SOW-THISTLE 1 3 2 4 1 One of the first young leaves with its round to oval terminal lobe 2 As the plant grows, older leaves have the characteristic triangularshaped terminal lobe 3 A young rosette in early June 4 A rosette found in a cornfield in late June 5 The yellow flower head with hairless bracts 5 WEED ID GUIDE FOR ONTARIO CROPS 69 DANDELION Composite or aster (Asteraceae family) • Taraxacum officinale G.H. Weber ex Wiggers EPPO Code: TAROF Other Names: dent-de-lion, lion’s-tooth, cankerwort SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed. Emergence: Since mature seeds lack primary dormancy, they are able to germinate as soon as they leave the plant. Seed will germinate over a wide range of temperatures (5–35˚C). Seed germination, however, is reduced when passed through the digestive tracts of cattle. Habitat: Dandelion can be found pretty much anywhere in Ontario in lawns, pastures, roadsides, wastes places, forages and cultivated fields, especially under reduced tillage. Competitiveness: Crop yield loss due to dandelion depends on the density of the weed. In University of Guelph trials, inadequate control of dandelion prior to planting soybean has resulted in average yield losses of 25 percent. IDENTIFICATION CLUES Seedling Cotyledons: Circular or oval.First leaves: Dandelion first appears as a basal rosette. Its primary leaves lack hair and are more oval than later emerging leaves, which are irregularly toothed with wavy margins. Mature leaves: When broken, the mature leaves of dandelion often exude a milky juice (latex). Leaves appear deeply and irregularly lobed/toothed. Mature plant Stems: Dandelion has no leaf stems. Instead, a hollow stalk rises from the middle of the basal rosette. This is where the flower head will emerge. Flowers: Dandelion flowers are yellow, 3–5 cm in diameter and grow at the end of a single hollow stalk. The flower has two rows of bracts; the outer row is bent backwards, while the inner row is erect. Seeds: Each dandelion seed is enclosed in a yellow-brown fruit that is 3–5 mm long. Seeds are attached to a white feathery pappus (often referred to as “fluff”) via a relatively long stalk that is about 8–10 mm. Collectively, all the fruit form a round whitish seed head that is easily dispersed by wind. Roots: Dandelion has a fleshy taproot that can be branched. OFTEN MISTAKEN FOR I know it’s NOT … because … Chicory … although it’s almost impossible to tell the difference between dandelion and chicory at the seedling and rosette stage, as the plants begin the reproductive phase the differences become obvious. Chicory has numerous bright blue flowers and there are numerous flower heads per stem; in addition chicory is much less common in cultivated fields. Prickly lettuce … dandelion lacks the row of spines on the underside of its leaf midrib. Annual sow-thistle … the young seedling leaves of dandelion lack the powdery coating that usually exists on the seedling leaves of annual sow-thistle. 70 WEED ID GUIDE FOR ONTARIO CROPS DANDELION 1 3 2 4 1 A seedling plant with its circular to oval cotyledon. The first 2–3 leaves are more or less orbicular, without deep lobes. 2 A fleshy taproot that has sprouted off several fibrous roots 3 Deeply-lobed mature leaves on a basal rosette 4 A large flowering plant 5 Flowering and mature inflorescences 5 WEED ID GUIDE FOR ONTARIO CROPS 71 COCKLEBUR Composite or aster (Asteraceae family) • Xanthium strumarium L. EPPO Code: XANST Other Names: bur, clotbur SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Seed germinates in early spring and into summer. Habitat: Cocklebur is most commonly found in cultivated fields in southwestern Ontario, but it can also be found in central and eastern Ontario, although mainly in areas close to lake Ontario. Competitiveness: Cocklebur is considered a very strong competitor. Yield losses above 50 percent have been observed in cereals, soybeans and field corn in Ontario. IDENTIFICATION CLUES Seedling Cotyledons: Long, narrow and smooth. Young leaves: The first leaves on a seedling plant are opposite and triangular shaped; subsequent leaves are alternate. The leaf surface is rough to the touch, not unlike sandpaper. Mature leaves: The mature leaves are alternate on the stem, broad, somewhat triangular and heart shaped at the base with rough toothed and wavy margins. The leaf surface is rough to the touch, similar to sandpaper, with prominent purplish veins that are “V” and “W” shaped. Mature plant Stems: Cocklebur’s stem is green with prominent purple spots and covered in with stiff hairs. Flowers: Its flowers grow in clusters in the axils of leaves with both male and female flowers on the same plant. Male flowers are rounded, while female flowers are enclosed in the bur. Seeds: Each bur contains two fruit; each fruit has one seed. The seeds are very hard to extract from the fruit. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Jimsonweed … although the cotyledons of both plants are similar, the leaves of cocklebur feel rough like sandpaper and lack the pungent odour that jimsonweed has when vegetative tissue is crushed. 72 WEED ID GUIDE FOR ONTARIO CROPS COCKLEBUR 1 4 5 1 A seedling plant with long narrow cotyledons and narrow triangular leaf 2 2 A mature leaf shown in August with prominent purple veins and rough toothed, wavy margins 3 The stem with its prominent purple spots and coarse short hairs 4 A large plant found in a corn field during early August 5 Fruiting shoot of common cocklebur 3 WEED ID GUIDE FOR ONTARIO CROPS 73 DOGBANE* Dogbane family (Apocynaceae family) • Apocynum androsaemifolium L. EPPO Code: APCAN Other Names: spreading dogbane, Indian hemp * POISONOUS TO LIVESTOCK WHEN CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and by spreading underground rhizomes. Emergence: Seed germinates in early spring and into summer. Habitat: Dogbane is found in a variety of habitats, including cultivated fields. It is, however, more likely to be found in no-till or minimum-till cropping systems. Competitiveness: When compared to annual dicot weeds, like lamb’s-quarters, dogbane causes less crop yield loss, but it does reduce harvest efficiency. The milky sap affects crop quality; it also contains cardiac glycosides, which can cause livestock poisoning (United States Department of Agriculture, 2006). IDENTIFICATION CLUES Seedling Cotyledons: Linear to elongated. Young leaves: Ovate, opposite orientation on the stem. Mature leaves: While they look similar to its younger leaves, dogbane’s mature leaves are larger and have a prominent, white mid-vein and its underside has fine hairs. Mature plant Stems: Its stem is erect, hairless, and often red to greenish-red in colour. When its leaves are pulled from the stem, dogbane exudes a milky sap. Flowers: Clustered at the end of stems, whitish to pinkish and bell shaped. Seeds: Light brown and slender, dogbane’s seeds are attached to a white silky parachute. Roots: Very fine roots attached to an extensive spreading rhizome system. OFTEN MISTAKEN FOR I know it’s NOT … because … Milkweed … the leaves of dogbane are narrower; the stem is red compared to the oftengreen stem of milkweed; and the flowers of dogbane are white compared to the purplishpink flowers of milkweed. 74 WEED ID GUIDE FOR ONTARIO CROPS DOGBANE 1 4 2 5 1 Milky juice exuding from the stem after a leaf is torn off 2 Leaves are orientated oppositely on the stem with two per node 3 A close-up of the top part of a flowering plant with its characteristic red stem 4 The woody rhizome that is easily broken at the soil’s surface, but spreads extensively underground 5 A flowering plant in early July 3 WEED ID GUIDE FOR ONTARIO CROPS 75 NORTHERN WILLOWHERB Evening-primrose (Onagraceae family) • Epilobium ciliatum Raf. EPPO Code: EPIAC Other Names: fringed willowherb SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and possibly underground root buds. Emergence: Typically germinates in the spring and fall. Habitat: Northern willowherb is found throughout Ontario, but it grows most commonly in moist places, along roadsides and in waste areas. More recently, it has been found on occasion in no-till fields planted to glyphosate tolerant soybeans. It appears to be tolerant to glyphosate. Competitiveness: No data exits on the competitiveness of northern willowherb. One study indicates, however, that soil that contains rye root residues will lower seed germination of willowherb (Przepiorkowski and Gorski, 1994). IDENTIFICATION CLUES Seedling Cotyledons: Egg-shaped to rectangular (rhomboid), small. Young leaves: Northern willowherb’s first leaves are long-oval and opposite. Subsequent leaves are lance-shaped and opposite. Mature leaves: Mature leaves are thickly veined, opposite, lance-shaped and have finelytoothed margins. They are opposite but become alternate near the top. Mature plant Stem: Northern willowherb’s stem is branched to erect, grows 1.5 m or taller and is covered in bristly hairs. Flowers: Its flowers are small and have four pink to purple petals that are lobed (giving it the appearance of eight petals) and stamens that have yellow anthers on purplish filaments. Fruit: Slender, straight, cylindrical seedpods with four chambers contain egg-shaped seeds that are flattened and end with a tuft of long, soft hairs. Roots: Creeping root system. 76 WEED ID GUIDE FOR ONTARIO CROPS NORTHERN WILLOWHERB 3 1 4 2 1 A patch of willowherb in soybean that had escaped an application of glyphosate 2 A close-up of opposite, lanceshaped leaves that are discoloured red from an earlier application of glyphosate 3 A lance-shaped leaf with finely toothed margins and prominent veins 4 A flowering plant with pinkishpurple petals in early July in a soybean field WEED ID GUIDE FOR ONTARIO CROPS 77 YELLOW EVENING-PRIMROSE Evening-primrose (Onagraceae family) • Oenothera biennis L. EPPO Code: OEOBI Other Names: common evening-primrose, evening-primrose SPECIES INFORMATION Lifecycle: Biennial or short-lived perennial. Propagation: Reproduces by seed. Emergence: According to Hall et al. (1987), seeds do not germinate if placed deeper than 5 mm in the soil. Seeds prefer warm soils, so peak germination likely occurs in late spring to early summer. Habitat: Yellow evening-primrose is found throughout Ontario, but most commonly on roadsides, in waste areas and pastures, and more recently in crop fields under no-till production. Competitiveness: No data exits on the competitiveness of yellow evening-primrose. IDENTIFICATION CLUES Seedling Cotyledons: Rhomboid, very small (100 mm), with a stalk the same length. Young leaves: Grows initially as a basal rosette. The rosette leaves are spoon-shaped with a prominent primary vein that is white and often tinged with pink or red. Sometimes with red blotches near the tip. Mature leaves: Stem leaves are alternate, narrow, long and have a pointed tip and prominent veins. Mature plant Stem: The weed’s stem is erect and grows up to 2 m in height. It is branched at the base, hairy, and green with a reddish tinge or red spots. Flowers: The flowers of yellow evening-primrose have four large yellow petals with four narrow greens sepals underneath that originate from the leaf axil. They form a dense terminal spike. Fruit and seeds: Has long, cylindrical seed pods that are green, hairy and covered in red spots. The inside is divided into four chambers, each of which contains several irregular-shaped, reddish-brown to black, rough-surfaced seeds that are roughly 1.5 mm long. Roots: Taproot Note of interest Traditionally, the young leaves and taproot have been consumed as a cooked vegetable (Hall et al., 1987). 78 WEED ID GUIDE FOR ONTARIO CROPS YELLOW EVENING-PRIMROSE 1 2 4 1 The rosette in early May 3 2 Its stem leaves are long and narrow with alternate orientation 3 The hairy green seed pods with red spots at each leaf axil 4 The large, yellow four-petal flower with narrow green sepals below WEED ID GUIDE FOR ONTARIO CROPS 79 CORN SPEEDWELL Figwort or Snapdragon family (Scrophulariaceae family) • Veronica arvensis L. EPPO Code: VERAR Other Names: common speedwell, speedwell SPECIES INFORMATION Lifecycle: Winter annual, annual Propagation: Reproduces only by seed. Emergence: Seed germinates in the fall and in early spring. Habitat: Corn speedwell is most commonly found in fall/winter cereals and turf grass. It is rarely found in spring-planted field crops because primary tillage or pre-plant burn down removes young seedlings. Competitiveness: Corn speedwell is not considered a strong competitor and does not interfere with harvesting because it grows low to the ground and is often done flowering and producing seed by early summer. IDENTIFICATION CLUES Seedling Cotyledons: Oblong to ovate with a rounded tip. First leaves: Corn speedwell’s first leaves are opposite, roundish to egg shaped, hairy on both surfaces. The leaves also have margins with rounded teeth. Mature leaves: The mature upper leaves are oriented alternately on the stem. They are oblong in shape (reminiscent of mouse-eared chickweed) and have entire margins. Mature plant Stems: Corn speedwell’s steam is erect or spreading from the base and hairy. Flowers: Generally, corn speedwell flowers in the spring to early summer and then again in the fall. Each plant has numerous small, light blue/purple to white, four-petalled flowers on short stalks. Seed pods are heart shaped and hairy. Seeds: Each heart-shaped seed pod contains about 20 yellowish/orange seeds that are roughly 0.7 mm in size. Roots: Corn speedwell has a fibrous, shallow root system. OFTEN MISTAKEN FOR I know it’s NOT … because … Bird’s-eye speedwell … the flowers of corn speedwell grow on short stalks, whereas the flowers of bird’s-eye speedwell grow on very long stalks. Common speedwell … the leaves below corn speedwell’s flowers are alternate, whereas the leaves of common speedwell are opposite. Purslane speedwell … the leaves and stems of corn speedwell are hairy, while the leaves of purslane speedwell are smooth. Purslane speedwell has exclusively white flowers. 80 WEED ID GUIDE FOR ONTARIO CROPS CORN SPEEDWELL 1 4 2 5 1 A flowering plant found in corn during late June. 2 The lower egg-shaped leaves that are hairy and have round-toothed margins. 3 The oblong shaped upper leaves of corn speedwell are reminiscent of mouse-eared chickweed. 4 A plant just starting to show its small light blue/purple flowers. 5 A plant in full flower. 3 WEED ID GUIDE FOR ONTARIO CROPS 81 COMMON SPEEDWELL Figwort or Snapdragon family (Scrophulariaceae family) • Veronica officinalis L. EPPO Code: VEROF Other Names: gypsy-weed, speedwell SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and spreading rhizomes. Emergence: Seed germinates in the fall and in early spring. Habitat: Common speedwell is more commonly found in perennial cropland, such as pastures and forages as well as in lawns. Other annual and winter annual speedwell species are typically found in fall/winter cereal crops. Competitiveness: Common speedwell is not considered a strong competitor. IDENTIFICATION CLUES Seedling Cotyledons: Oblong to ovate with a rounded tip. First leaves: The first leaves of common speedwell are opposite and lemon shaped. They have finely-toothed margins and they are hairy on both sides. Mature leaves: Mature leaves remain opposite and the same size as the younger leaves, which is different from most other speedwell species. Mature plant Stems: The stem of common speedwell is hairy, much branched and grows more or less upright. Note that creeping stems will root at nodes that touch the ground. Flowers: Generally, common speedwell flowers in the spring to early summer, and then again in the fall. Each plant has dense, erect spikes that contain numerous small, light blue to light purple flowers on short stalks. The seed pod is heart shaped and hairy. Seeds: Each heart-shaped seed pod contains several yellowish/orange seeds that are roughly 0.5 mm in size. Roots: Fibrous roots at nodes of spreading rhizomes. OFTEN MISTAKEN FOR I know it’s NOT … because … Bird’s-eye speedwell … the leaves below common speedwell’s flowers are opposite, whereas bird’s-eye speedwell’s leaves are alternate and the flowers grow on a long stalk. Corn speedwell … the leaves below common speedwell’s flowers are opposite, whereas corn speedwell’s leaves are alternate. Purslane speedwell … purslane speedwell is hairless and has white flowers above alternating oblong leaves, whereas common speedwell is hairy with light blue/purple flowers that are lemon-shaped, hairy and oppositely oriented on the stem. 82 WEED ID GUIDE FOR ONTARIO CROPS COMMON SPEEDWELL 1 3 2 4 1 The lemon shaped leaves with finely toothed and hairy margins along with a hairy stem. 2 Creeping stems will root into the ground at nodes giving a “carpeted” appearance when a high density of the plant is established, in this case, in turfgrass. 3 Stems can also be upright with light blue/purple flowers on short stalks. 4 Seedpods are hairy and heart shaped. 5 Flowers have four petals and are a light blue/purple. 5 WEED ID GUIDE FOR ONTARIO CROPS 83 BIRD’S-EYE SPEEDWELL Figwort or Snapdragon family (Scrophulariaceae family) • Veronica persica Poir. EPPO Code: VERPE Other Names: bird’s-eye veronica SPECIES INFORMATION Lifecycle: Annual, winter annual. Propagation: Reproduces by seed only. Emergence: Seed germinates in the fall and in early spring. Habitat: Bird’s-eye speedwell is most commonly found in fall/winter cereals and turf grass. It is rarely found in spring-planted field crops because primary tillage or pre-plant burn down removes young seedlings. Competitiveness: Bird’s-eye speedwell is not considered a strong competitor and does not interfere with harvesting because it grows low to the ground and is often done flowering and producing seed by early summer. IDENTIFICATION CLUES Seedling Cotyledons: Oblong to ovate with rounded tip. First leaves: The first leaves of bird’s-eye speedwell are opposite, roundish to egg-shaped on short stalks, hairy on both surfaces and margins with coarse teeth. Mature leaves: The mature upper leaves are alternately oriented on the stem, but are more or less the same shape and size as the lower leaves. Mature plant Stems: Bird’s-eye speedwell’s stem grows upright, but weakly. It is often found lying on the ground and rooting from the nodes that touch the soil. Flowers: Generally, the plant flowers in the spring to early summer and then again in the fall. Each plant has numerous small, blue, four-lobed flowers on long stalks. Its seed pods are heart shaped and hairy. Seeds: Each heart-shaped seed pod contains several yellowish/orange seeds that are roughly 0.5 mm in size. Roots: Fibrous, shallow root system. OFTEN MISTAKEN FOR I know it’s NOT … because … Common speedwell … the leaves below bird’s-eye speedwell’s flowers are alternate, whereas common speedwell’s leaves are opposite. Corn speedwell … the flowers of bird’s-eye speedwell grow on long stalks, whereas the flowers of corn speedwell are stalkless. Purslane speedwell … purslane speedwell is hairless and has white flowers, whereas bird’s-eye speedwell is hairy and has light blue flowers on long stalks. 84 WEED ID GUIDE FOR ONTARIO CROPS BIRD’S-EYE SPEEDWELL 1 3 2 4 1 Bird’s-eye speedwell in winter wheat during early May 2 A flowering plant in winter wheat during early May 3 A close-up showing the numerous blue flowers along with hairy leaves with toothed margins. 4 The long flowering stalks and opposite leaves of Bird’s-eye speedwell distinguishes it from other speedwell species. 5 A close-up of the 4 petal, blue flower. 5 WEED ID GUIDE FOR ONTARIO CROPS 85 PURSLANE SPEEDWELL Figwort or Snapdragon family (Scrophulariaceae family) • Veronica peregrina L. EPPO Code: VERPG Other Names: neckweed SPECIES INFORMATION Lifecycle: Annual, winter annual. Propagation: Reproduces by seed only. Emergence: Seed germinates in the fall and in early spring. Habitat: Purslane speedwell is most commonly found in fall/winter cereals and turf grass. It is rarely found in spring-planted field crops because primary tillage or pre-plant burn down removes young seedlings. Competitiveness: Purslane speedwell is not considered a strong competitor and does not interfere with harvesting because it grows low to the ground and is often done flowering and producing seed by early summer. IDENTIFICATION CLUES Seedling Cotyledons: Oblong to ovate. First leaves: Purslane speedwell’s first leaves are opposite and oblong. They have smooth or irregularly-toothed margins, are hairless and have a fleshy texture. Mature leaves: The mature upper leaves of purslane speedwell are alternately oriented on the stem, and smaller and narrower than the lower leaves. Each upper leaf has a small, white flower in its axil on a short stalk. Mature plant Stems: The plant’s stem grows erect or branched from the base. The stalk may be smooth or have fine sticky hairs that give it a fleshy texture. Flowers: Generally, purslane speedwell flowers in the spring to early summer and then again in the fall. Each plant has numerous small, white, four-lobed flowers on short stalks. The seed pods are heart shaped and hairless. Seeds: Each heart-shaped seed pod contains several yellowish/orange seeds that are roughly 0.5 mm in size. Roots: Fibrous, shallow root system. OFTEN MISTAKEN FOR I know it’s NOT … because … Bird’s-eye speedwell … purslane speedwell is hairless and has white flowers, whereas bird’s-eye speedwell is hairy with light blue flowers. Common speedwell … the leaves below purslane speedwell’s flowers are alternate and hairless, whereas common speedwell’s are opposite and hairy. Corn speedwell … the leaves and stems of purslane speedwell are smooth and hairless compared to the hairy leaves and stems of corn speedwell. 86 WEED ID GUIDE FOR ONTARIO CROPS PURSLANE SPEEDWELL 4 1 5 2 1 A plant in heavy clay soil destined for soybean in mid-May. 2 The oblong first leaves with smooth to irregularly-toothed margins. 3 Opposite leaf orientation on younger and mid-stem leaves, the upper leaves generally have an alternate orientation on the stem. 4 A mature plant with numerous, small, white, four-petal flowers. 5 A close-up of the small, white, fourpetal flower. 3 WEED ID GUIDE FOR ONTARIO CROPS 87 COMMON MULLEIN Figwort or Snapdragon (Scrophulariaceae family) • Verbascum thapsus L. EPPO Code: VESTH Other Names: candlestick, devil’s tobacco SPECIES INFORMATION Lifecycle: Biennial Propagation: Reproduces by seed. Emergence: Common mullein seed germinates in early spring and grows as a rosette throughout the season. The rosette overwinters and then flowers, producing seed in its second year of growth. Habitat: Common mullein is found throughout Ontario, predominately in waste areas and pastures, and along roadsides. It is found less frequently in northwestern Ontario, perhaps due to the acidity of the soil there. The plant prefers a soil pH range of 6.5 to 7.8 (Gross and Werner, 1977). Competitiveness: Common mullein is not considered competitive nor a weed of agricultural concern since it does not thrive in cultivated landscapes. If common mullein is found in pastures it is usually a symptom of overgrazing. IDENTIFICATION CLUES Seedling Cotyledons: Round to orbicular with long stalk, hairy margins and surface. Young leaves: Common mullein’s first leaves form a basal rosette and are oblong in shape. The leaves are densely woolly and feel fuzzy when to the touch. Mature leaves: Its stem leaves are alternate, elongated to oblong and densely woolly. Mature plant Stems: In the second year the plant bolts with an elongated stem that ranges from 1–2 m in height. Flowers: Common mullein’s flowers grow in an elongated spike (20–50 cm long) with numerous yellow, five-petal flowers. Sometimes the plant has numerous branched spikes on top. Seeds: They are contained in brown capsules in a dense seed-head. Its seeds are extremely small, reddish-brown and deeply grooved, resembling tiny corn cobs. Roots: Taproot with shallow secondary fibrous roots. OFTEN MISTAKEN FOR I know it’s NOT … because … We can’t think of many species that would be confused with common mullein. Its distinct, densely woolly leaves and long spike made up of numerous yellow five-petal flowers make it a unique species. 88 WEED ID GUIDE FOR ONTARIO CROPS COMMON MULLEIN 1 4 2 5 1 A seedling with round cotyledons and round woolly first leaves 2 The basal rosette with densely woolly leaves 3 An elongated stem in the plant’s second year of growth with alternate woolly leaves 4 A long spike with many five-petal yellow flowers 5 A mature seed head in November 3 WEED ID GUIDE FOR ONTARIO CROPS 89 SPREADING ATRIPLEX Goosefoot (Chenopodiaceae family) • Atriplex patula L. EPPO Code: ATXPA Other Names: halberdleaf orach, , spear saltbush SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed , has separate male and female plants (dioecious). Emergence: Emerges in the spring and is one of the first summer annual weeds to emerge, often before lamb’s-quarters. Habitat: In cultivated fields it is most often found on heavier textured soils but will exist on many soil types. Competitiveness: No published data exists on crop yield losses but presumably similar to its very competitive cousin, lamb’s-quarters. Resistance: No confirmed cases of resistant populations. IDENTIFICATION CLUES Leaves Cotyledons: Linear with a very short petiole and a rounded tip. Young leaves: Oval-lanceolate, often egg-shaped and lightly coated with white, mealy powder. Mature leaves: Irregular toothed margin, green with two prominent basal lobes, the base distinctly triangular. Lightly covered in white mealy powder. Mature plant Stem: Stems are wiry and smooth. Opposite leaf orientation (2 per node) on the stem. Flowers and seed heads: Very small inconspicuous flowers in dense green clusters. Female plants produce irregularly shaped seed pods enclosed by diamond shaped bracts. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Lamb's-quarters ... Spreading atriplex has much narrower leaves with two prominent sharp basal lobes compared to lamb’s-quarters much broader triangular shaped leaf. Spreading atriplex also has a wiry stem with opposite leaf orientation compared to the much more branched lamb’s-quarters with its alternate leaf orientation. Fig-leaved goosefoot ... Fig-leaved goosefoot leaves look very similar as they too have the prominent basal lobes. However, the leaf shape above those basal lobes is rectangular but with a round apex. With spreading atriplex, the leaf blade above the basal lobes is triangular with a pointed apex. In addition, the basal lobes of fig-leaved goosefoot are rounded while those of atriplex are pointy. 90 WEED ID GUIDE FOR ONTARIO CROPS SPREADING ATRIPLEX 4 1 5 2 1 Seedling plants at the 2-leaf stage during the first week of May 2 The first leaf of spreading atriplex (left), compared to a leaf typical of the 8–10 leaf stage of growth (right) 3 Although the orientation of leaves may appear alternate on young seedling plants, leaf orientation on mature plants is clearly opposite 4 Spreading atriplex has two distinct lobes at the base of its leaf (right) differentiating it from common lamb’s-quarters (left) 3 5 Clusters of flowers with their distinctly diamond shaped bracts WEED ID GUIDE FOR ONTARIO CROPS 91 LAMB’S-QUARTERS Goosefoot (Chenopodiaceae family) • Chenopodium album L. EPPO Code: CHEAL Other names: fat-hen, pigweed, white goosefoot, white pigweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: One of the first annual weeds to emerge in the spring. It will generally emerge over a 6–7 week period with the majority of its total emergence occurring within the first 2–3 weeks. Habitat: Found in most cultivated fields. Less prevalent in winter cereals and established forage crops. Competitiveness: Considered one of the most competitive annual broadleaf weeds in Ontario. Agriculture and Agri-Food Canada research demonstrated yield losses in corn that ranged from 11 percent (at 2000 plants/ac) to 95 percent (at 128,000 plants/ac). Resistance: A number of populations are resistant to Group 2 (e.g. imazethapyr) and Group 5 (e.g. atrazine) herbicides in Ontario and throughout North America. IDENTIFICATION CLUES Leaves Cotyledons: Linear, narrow, fleshy in appearance with a distinct stalk, reddish-purple underneath. Young leaves: Ovate (egg-shaped) often coated with white, mealy powder. Mature leaves: Triangular and broad with irregular toothed margins, covered in white mealy powder. Mature plant Stem: The first 2–4 leaves have an opposite orientation (2 per node) on the stem but later leaves have an alternate orientation. The stems are generally smooth, but can feel gritty due to the presence of white mealy powder. There are red to purple lengthwise ridges on the stem. Flowers and seed heads: Very small globular green flowers are arranged in a compact inflorescence. The seed head takes a granular looking appearance at maturity. Seeds are small, black, round and flattened. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Spreading atriplex … Spreading atriplex has a much narrower leaves with two prominent basal lobes lacking the white-mealy powder compared to lamb’s-quarters much broader triangular shaped leaf. Spreading atriplex also has a wiry-stemmed opposite leaf orientation compared to the much more branched lamb’s-quarters with its alternate leaf orientation. Figleaved goosefoot … Fig-leaved goosefoot has much narrower, pale-green leaves with wavy toothed margins and two prominent basal lobes compared to the broad, dark-green triangular shaped leaves of lamb’s-quarters. Oak-leaved goosefoot … As the name implies, it has “oak-leaf” shaped leaves with prominent white veins. Its fleshy, dark-green leaves are distinctly different from lamb’s-quarters. It also has more of a creeping habit than an upright habit. 92 WEED ID GUIDE FOR ONTARIO CROPS LAMB’S-QUARTERS 1 4 5 1 A 2-leaf seedling plant with its narrow cotyledons 2 2 A 4-leaf seedling plant with cotyledon leaves beside an 8-leaf plant 3 The first leaf (left) compared to a more mature leaf (right) 4 A large plant at the beginning of flowering 5 A mature seedhead above a soybean crop canopy along with redroot pigweed 3 WEED ID GUIDE FOR ONTARIO CROPS 93 FIGLEAVED GOOSEFOOT Goosefoot (Chenopodiaceae family) • Chenopodium ficifollium Sm. EPPO Code: CHEFI Other names: fig-leaved goosefoot, chénopode à feuilles de figuier SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Emerges early in the spring with a similar emergence pattern to lamb’squarters. Habitat: Similar to lamb’s-quarters, mainly found in cultivated fields or any landscape where soil disturbance is frequent. It is not as prevelant as lamb's-quarters. Competitiveness: No published data exists on crop yield losses but presumably similar to the very competitive lamb’s-quarters. Resistance: No documented cases of herbicide resistant populations in Ontario IDENTIFICATION CLUES Leaves Cotyledons: Linear, similar to lamb's-quarters. Young leaves: Lanceolate, often with two very small lobes at the base, and lightly coated with white, mealy powder. Mature leaves: Hastate, with irregular toothed margins, two prominent basal lobes and lightly covered in white mealy powder. Mature plant Stem: The first 2–4 leaves have an opposite orientation (2 per node) on the stem, subsequent leaves are oriented in an alternate orientation (1 per node). Flowers and seed heads: Clusters of green, round and irregularly shaped flowers, very compact inflorescence much like that of lamb's-quarters. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Lamb’s-quarters … Lamb’s-quarters has much broader, triangular leaves that are darker green. Spreading atriplex … Spreading atriplex leaves look very similar as they too have the prominent basal lobes. However, the leaf shape above those basal lobes is triangular with a sharp point. With fig-leaved goosefoot, the leaf shape above the basal lobes is more rectangular with a rounded apex. Oak-leaved goosefoot … As the name implies, it has “oak-leaf” shaped leaves, fleshy with prominent white veins. It typically has deep red stems and more of a creeping habit than the upright habit of figleaved goosefoot. 94 WEED ID GUIDE FOR ONTARIO CROPS FIGLEAVED GOOSEFOOT 4 1 5 1 8-leaf stage seedling 2 2 Figleaved goosefoot (right) next to common lamb’s-quarters (left) 3 The first leaf of figleaved goosefoot (left) compared with a later emerging leaf 4 One common lamb’s-quarters surrounded by figleaved goosefoot 5 Flowering plant 3 WEED ID GUIDE FOR ONTARIO CROPS 95 KOCHIA Goosefoot family (Chenopodiaceae family) • Kochia scoparia (L.) Schrad. EPPO Code: KCHSC Other Names: belevedere, red belvedere, Mexican fireweed, summer-cypress SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Seedlings emerge in the spring. Habitat: Kochia is rarely found in Ontario, however, more recently it has shown up in new seedling alfalfa stands, presumably from contaminated alfalfa seed from Western Canada. Competitiveness: Kochia densities of six plants/m2 did not reduce yields of oat, but in two of five years a density of 30 plants/m2 caused between 12–31 percent yield loss (Manthey et al., 1996). In 2014, Lewis and Gulden identified a 5 percent yield loss action threshold in sunflower at a kochia density of four plants/m2 when they emerged at the same time as the crop. Resistance: Most populations in Western Canada are resistant to group 2 herbicides and some are resistant to glyphosate. Some Ontario populations are group 2 resistant but there are no known cases of glyphosate resistant kochia in the province. IDENTIFICATION CLUES Seedling Cotyledons: Elongated, without a stalk. First leaves: Kochia’s first leaves are elongated and somewhat club-shaped. They are covered in soft, dense hairs. Leaves form a basal rosette. Mature leaves: Mature leaves grow in alternate orientation, are elongated and somewhat club-shaped, and covered in soft, dense hairs. Mature plant Stems: Its stem is erect, much-branched, and often red-tinged with green. It is covered in short, soft white hairs. Flowers: Kochia’s flowers are subtle, small, round, green and clustered. In many ways, they are like the flowers of kochia’s close relative, lamb’s-quarters. Seeds: Kochia has bladder-like seed pods with irregularly-shaped brown seeds. The seeds have yellow markings and are grooved on each side. Roots: Taproot with branched fibrous roots. 96 WEED ID GUIDE FOR ONTARIO CROPS KOCHIA 4 1 5 2 1 A seedling plant with elongated cotyledons 2 An older seedling plant with densely hairy, club-shaped leaves 3 The reddish stem with fine white hairs and alternate leaf orientation 4 A flowering plant with green, round flowers that are turning into brownish-yellow seed capsules 5 A mature plant 3 WEED ID GUIDE FOR ONTARIO CROPS 97 WILD CUCUMBER Gourd or Melon (Cucurbitaceae family) • Echinocystis lobata (Michx.) Torr. & A. Gray EPPO Code: ECNLO Other Names: prickly cucumber, balsam apple SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Explosive fruit projects seeds to a long distance. Emergence: Seed germinates in early spring. Habitat: Wild cucumber is found along creeks and field edges, particularly near woodlots. Recently, it has been creeping into cultivated crops, most likely aided by wild animals, such as wild turkey that eats the seed. Competitiveness: Little data exists on this species competitiveness; however, due to its vine-like nature, it does negatively affect harvesting efficiency when in field crops. IDENTIFICATION CLUES Seedling Cotyledons: Oblong, without a petiole, showing prominent veins, 35-45 mm long. Young leaves: Ovate, opposite orientation on the stem. Mature leaves: The mature leaves of wild cucumber are bright green and five-lobed, somehow star-shaped or roughly similar to a maple leaf.. They have smooth or soft-toothed margins. Mature plant Stems: Its stem is smooth. Using its tendrils that grow at each leaf node and opposite to the leaf, the stem creeps and climbs along objects. Flowers: Male flowers have small, white petals with prominent yellow anthers. Female flowers have yellow green petals on top of a spherical spiny ovary and grow immediately below each cluster of male flowers. Fruit: fleshy, oblong, 2.5–5 cm long, covered with soft spikes. Seeds: Wild cucumber’s seeds are oval or egg-shaped, and light brown with dark brown lines around the margins. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Bur cucumber … Wild cucumber has leaves that are more deeply lobed and “star-shaped” compared to the shallow lobed leaves of bur cucumber. Its stems are usually smooth, and its flowers have six rather than five petals and sepals. 98 WEED ID GUIDE FOR ONTARIO CROPS WILD CUCUMBER 1 4 2 5 1 A two-leaf seedling plant in midMay 2 The distinct five-lobed bright green leaves 3 A close-up of the tendril that wraps around objects causing the plant to climb and creep around 4 The fleshy round fruit of wild cucumber covered in soft spikes 5 Fruit on the ground in late September beside seed that had dispersed from a neighboring fruit 3 WEED ID GUIDE FOR ONTARIO CROPS 99 BUR CUCUMBER Gourd or Melon (Cucurbitaceae family) • Sicyos angulatus L. EPPO Code: SIYAN Other Names: burr cucumber, star cucumber SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed Emergence: Bur cucumber will emerge from May to August, but the majority of seedlings will emerge in June. It is considered a later emerging annual weed. Habitat: Bur cucumber is native to North America. It prefers damp soil and is most commonly found in low-lying areas near rivers and creeks. Competitiveness: The species is very competitive. Its creeping, vine-like nature causes significant reductions in crop harvesting efficiency. IDENTIFICATION CLUES Seedling Cotyledons: Thick and oblong or spoon shaped, bur cucumber cotyledons resemble ordinary cucumber cotyledons and are covered in spreading hairs. Mature leaves: Mature leaves have alternate leaf orientation. They are broad and heart shaped, have toothed margins, and 3–5 points or shallow lobes. The upper surface of each leaf is light green and hairy. Stems attach in the narrow space between the lobes of the heart-shaped leaf base. Mature plant Stem: Vine-like stems climb over vegetation and fences or sprawl across the ground using branched tendrils, similar to those found on pea plants. The stems are light green, round or furrowed, quite hairy, and have a sticky surface. Flowers: Bur cucumber has both male and female flowers, which are bunched together in short clusters of 3–10 flowers (raceme) on the same plant. Male flowers have green calyx with five teeth, white petals with five spreading lobes, and bloom in clusters towards the end of the raceme. Female flowers have a large ovary, which is enclosed within an ovoid fruit. The fruit is covered with sharp spines and long white hairs that are initially green, but later turn brown. Bur cucumber blooms from late summer to early fall. Fruit: Growing in clusters of 3–20, the fruit of bur cucumber resemble very small cucumbers that are more round than regular cucumber-shaped and covered in long bristles. The burrlike fruit contain a single, large seed that is brown and flat. Roots: Shallow, fibrous and branched taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Wild cucumber … wild cucumber has leaves that are more deeply lobed and “star shaped.” Its stems are usually smooth, and it flowers with six rather than five petals and sepals. 100 WEED ID GUIDE FOR ONTARIO CROPS BUR CUCUMBER 1 3 2 4 1 Thick and oblong or spoon-shaped cotyledons, resembling ordinary cucumber cotyledons 2 A seedling plant in late June at the maximum stage for control with post-emergent herbicides 3 Mature plants exhibiting the vine growth habit in a cornfield during early August 4 The five-pointed mature leaf 5 A close up of the pointed fruit covered in whisker-like hairs 5 WEED ID GUIDE FOR ONTARIO CROPS 101 GOLDENCREEPER Gourd or Melon (Cucurbitaceae family) • Thladiantha dubia Bunge EPPO Code: THDDU Other Names: thladianthe SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by underground tubers. Emergence: Goldencreeper’s shoots emerge from a tuber; peak emergence takes place typically in late May to early June. Habitat: This species can be found in scattered regions in southern Ontario. Most commonly, though, it is found in old gardens, along roadsides, and in waste areas and cultivated fields. Competitiveness: No information exists on the competitiveness of this species, but its climbing nature can negatively affect harvesting efficiency. IDENTIFICATION CLUES Young plant Young leaves: Goldencreeper has alternate leaf orientation. Leaves grow on short stalks and are broadly heart shaped with a deep, rounded U-shaped base, smooth margins and a slender, pointed tip that stretches out beyond the rest of the leaf. The leaves have rough hair on both surfaces. Mature leaves: Mature leaves appear the same as the species’ first leaves, only larger. Mature plant Stems: The plant has slender, twining, vine-like stems that climb over other plants or spread over the ground by way of tendrils. Each stem can be 1–2 m in length. Flowers: Goldencreeper produces showy, bright yellow flowers. Goldencreeper has only male (pollen-producing) flowers. The plant blooms from July to September. Roots: Goldencreeper has large, fleshy, underground, fingerling potato-like tubers that are wide spreading and very persistent. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild cucumber … wild cucumber leaves have five lobes, and its fruit resemble small, spiny cucumbers. Goldencreeper’s leaves, on the other hand, are broad and heart-shaped and the plant produces fingerling potato-like tubers. 102 WEED ID GUIDE FOR ONTARIO CROPS GOLDENCREEPER 4 1 5 2 1 Close-up of goldencreeper’s potato-like tuber that produces the vegetative shoots 2 A young plant in mid-June with its broad, heart-shaped leaves 3 A close-up of the hairy stem with tendrils that allow the plant to climb objects 4 A plant with tuber and vegetative shoots 5 The yellow five-petal flower 3 WEED ID GUIDE FOR ONTARIO CROPS 103 FIELD HORSETAIL* Horsetail (Equisetaceae family) • Equisetum arvense L. EPPO Code: EQUAR Other Names: horse-pipes, joint grass, mare’s tail * POISONOUS TO HORSES WHEN CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Field horsetail reproduces by spores, and most commonly, by rhizomes. Emergence: The spore-producing reproductive shoots of field horsetail emerge first, typically in early May. The green vegetative shoots emerge shortly after. Habitat: Field horsetail is found throughout Ontario. It is very common in poorly drained soil but can be found in well drained gravely or sandy soils. Toxicity: Field horsetail contains thiaminase, an enzyme that will cause thiamine deficiency in horses. The side effects include weakness, a rapid pulse and muscular exhaustion (Kingsbury, 1964). This weed is rarely lethal to cattle (Kinsbury, 1964), most likely because thiamine can be produced in the rumen. Competitiveness: Very little data exists on crop yield loss from field horsetail competition. When field horsetail at a density of 1.6 million shoots/acre was left uncontrolled all season, corn silage yields in Quebec were reduced by 95 percent. In contrast, an Ontario study concluded that field horsetail is not a serious competitor with corn. When left uncontrolled, corn grain yields were only reduced once (by 13 percent) in four experiments. However, the study provided no information as to the density of field horsetail in each of the experiments, and one can assume that yield loss relationships are density-dependent. IDENTICATION CLUES Reproductive shoots: The reproductive shoots of field horsetail are light brown to gray, unbranched and hollow stemmed with a spore-producing cone on top. Vegetative shoots: The first leaves of field horsetail are circular, flat and rounded with wavy margins. Its second leaf is similar, but with toothed margins. Roots: Creeping, horizontal rhizome OFTEN MISTAKEN FOR I know it’s NOT … because … Scouring rush … field horsetail is much shorter with many green branches and resembles a pine tree. Scouring rush, on the other hand, is taller, lacks branches and resembles a green bamboo pole. 104 WEED ID GUIDE FOR ONTARIO CROPS FIELD HORSETAIL 1 4 2 5 1 Horsetail in winter wheat during early May with the brownish sporeproducing shoots and the green, pine tree-like vegetative shoots 2 A close-up of the brown sporeproducing shoot, which emerges first in spring 3 A close-up of the vegetative shoot 4 A vegetative shoot in winter wheat during mid-May 5 An infestation of vegetative shoots prior to planting soybeans in early June 3 WEED ID GUIDE FOR ONTARIO CROPS 105 SCOURING RUSH* Horsetail (Equisetaceae family) • Equisetum hyemale L. EPPO Code: EQUHY Other Names: snake grass, bamboo weed * POISONOUS TO HORSES WHEN CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by spores and most commonly by rhizomes. Emergence: Typically emerges from late April to early May. Habitat: Scouring rush is native to North America. It grows in dense patches, and prefers sun and wet or moist conditions, gravel, sandy or “mucky” soil. Competitiveness: No data exists on scouring rush’s competitiveness. It is rarely found in fields, but typically along field edges. IDENTIFICATION CLUES Stem: Scouring rush is a leafless, bamboo-like plant. It has a single green (grey, olive to dark green), rough and hollow stem. Stiff and unbranched, it has multiple “joints” or nodes that segment the stem into several 2–4 cm long sections that bend and break apart easily. The stem grows between 20 and 150 cm tall. Sterile and fertile stems look alike; they are encircled by ash-coloured bands and have small ridges that run lengthwise down the stem. Spore-bearing cone: Scouring rush grows a spore-bearing cone at the tip of its stem. Usually black or white in colour, it is pointed and grows up to 2.5 cm long. The cones release spores in late spring to mid-summer. Roots: Extensive rhizome, fibrous secondary roots Party time trivia This primitive plant has a prehistoric look to it. The plant’s name comes from its historical use as a scrub for pots and pans, and also because it contains silica and was used as a polish to finish pewter, wood, ivory, silver and brass. OFTEN MISTAKEN FOR I know it’s NOT … because … Field horsetail … scouring rush is taller, lacks branches and resembles a green bamboo pole. 106 WEED ID GUIDE FOR ONTARIO CROPS SCOURING RUSH 4 1 5 2 1 A plant from a field in Essex County in late April 2 A vegetative shoot that emerged in cornstalks in late April 3 A close-up of the vegetative shoots, which are hollow and have grayish nodes 4 An infestation of scouring rush along the edge of a field 5 Another close-up of the vegetative shoot 3 WEED ID GUIDE FOR ONTARIO CROPS 107 BLACK MEDICK Legume (Fabaceae family) • Medicago lupulina L. EPPO Code: MEDLU Other Names: yellow clover, lupuline, luzerne SPECIES INFORMATION Lifecycle: Annual, winter annual or biennial. Propagation: Reproduces by seed. Emergence: Seeds germinate in early autumn or spring. Habitat: Found throughout the province in various types of soils; in cultivated fields it prefers environments with little soil disturbance, therefore is most often found in no-till or minimum till cropping systems. Competitiveness: Limited Ontario field trials have demonstrated as much as 20% yield losses from moderate to heavy populations. IDENTIFICATION CLUES Seedling Cotyldeons: Elongated to oblong with a rounded tip and base, stalkless. Young leaves: the first leaf is entire, broad oval, borne on a long stalk, the following leaves are compound trifoliolate, the central leaflet has a short stalk. Mature leaves: Alternate, compound trifoliolate leaves with round to wedge-shaped leaflets, each with shallow toothed margins. Like its close relative alfalfa, the middle leaflet has a longer stalk than the middle leaflets. Mature plant Stems: Wiry, long and prostrate lying on the ground or short, erect and spreading. Flowers: Individually very small but grouped in dense clover-like, yellow clusters on long stalks; flowers from spring to autumn; seedpods resemble a bundle of small black coils. Seeds: Kidney-shaped, 1.5–2.5 mm long; orange to orange-brown. Roots: Taproot with secondary branched roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Woodsorrel … woodsorrel has heart-shaped leaflets and flowers with 5 petals compared to the oval leaflets and round to egg-shaped and clustered flowers of black medick. Clovers … clover species have relatively similar compound leaves, but the center leaflet does not have a longer stalk. 108 WEED ID GUIDE FOR ONTARIO CROPS BLACK MEDICK 1 4 2 5 1 A newly emerged seedling with elongated cotyledons and unifoliate leaf 2 A flowering plant in a corn field during mid-June 3 A close-up showing the compound leaves with 3 leaflets and yellow flowers 4 Close-up of the dense cluster of small yellow flowers 5 Side profile a flowering plant 3 WEED ID GUIDE FOR ONTARIO CROPS 109 COMMON YELLOW WOODSORREL Oxalis (Oxalidaceae family) • Oxalis stricta L. EPPO Code: OXAST Other names: yellow woodsorrel, woodsorrel, sour grass, sour clover SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and by rhizomes. Emergence: Spring Habitat: This species has been found predominately in lawns, waste areas, roadsides and pastures, but occasionally it has been found in crops grown using minimum tillage (no-till) practices. Competitiveness: No data exists on the competitiveness of woodsorrel. IDENTIFICATION CLUES Leaves Cotyledons: Round, oval, with a very short stalk as if they were directly attached to the stem. Young and mature leaves: Woodsorrel has three heart-shaped leaflets that make up the trifoliolate leaf. Often, they are bright green in colour, but they can be purplish-green, especially when coming out of the winter. Leaves grow on a long petiole and have margins with fringed hairs. Mature Plant Stem: Mature plants have alternate leaf orientation. The stem is green to purple, hairy, and branched at the base. Flowers: Woodsorrel’s flowers are yellow, with five petals and 4–10 mm in diameter. Seed pods are long and look somewhat like a straight green banana. The flowers disperse seed by rupturing and ejecting seed as far as 2 m (Doust et al., 1985). Seeds: Its seeds are 1–1.5 mm long, football shaped, and ridged with a sticky coating. They are rusty brown in colour. Roots: A secondary fibrous root system grows from long white to pink rhizomes. Note of interest The plant’s leaves contain oxalic acid, which gives it a sharp, vinegar to citrus-like taste. Historically, the leaves have been dried and added to dishes for flavouring. Some species of woodsorrel may accumulate lethal concentrations of soluble oxalates (Doust et al., 1985), although our guess is that one would have to consume quite a bit for that to be a concern. OFTEN MISTAKEN FOR I know it’s NOT … because… Black medick … woodsorrel has heart-shaped leaflets and flowers with 5 petals compared to the oval leaflets and round to egg-shaped and clustered flowers of black medick. 110 WEED ID GUIDE FOR ONTARIO CROPS COMMON YELLOW WOODSORREL 1 3 2 4 1 Vegetative growth in early spring originating from rhizomes 2 A flowering patch in mid-June 3 Trifoliolate leaf with three heartshaped leaflets 4 The yellow, five-petal flowers 5 A mature plant with three seed pods at the top 5 WEED ID GUIDE FOR ONTARIO CROPS 111 KUDZU Legume or Bean (Fabaceae family) • Pueraria montana (Lour.) Merr. EPPO Code: PUELO Other Names: foot-a-night vine, vine-that-ate-the-South, Ko-hemp SPECIES INFORMATION Lifecycle: Perennial Propagation: Kudzu reproduces rarely by seed and more commonly through crown roots and stem nodes. Emergence: The thick seed coat generally leads to high dormancy and low seed germination (Frye, n.d.). New plants are primarily established through vegetative reproduction. Growth begins in early spring. Habitat: The only known location where kudzu has been found in Ontario is on the coast of Lake Erie near Kingsville. It is speculated that this patch was established on purpose to prevent the erosion of a steep embankment. Competitiveness: Kudzu is extremely competitive and invasive. It easily smothers other vegetation. IDENTIFICATION CLUES Seedling Cotyledons: Oblong, similar to soybean cotyledons. Young leaves: Kudzu’s first leaves are round. The first two leaves are unifoliate, while subsequent compound leaves are trifoliolate, or made up of three leaflets. Mature leaves: Mature leaves appear as compound leaves with three leaflets. The middle leaflet grows on a longer petiole than the other two. The leaflets are ovate to three-lobed, similar to ivy. Mature plant Stems: Hairy, woody and vine-like with nodes that root into the ground and facilitate the aggressive creeping growth habit of the plant. Flowers: Flowers grow on a 10–20 cm long raceme. The flowers are numerous, purple and fragrant, and produce flattened, hairy seed pods that are 4–5 cm long and contain multiple seeds. Seeds: Kidney-shaped, brown, mottled with black, they are reminiscent of small pinto beans. Roots: Extensive fleshy root systems with numerous adventitious roots; deeply penetrating. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild cucumber … kudzu has compound leaves with three leaflets and stems with nodal roots that anchor into the grown, while wild cucumber has five-lobed leaves and tendrils. Poison ivy … kudzu has hairy stems with nodal roots that anchor in the ground, while the stem of poison ivy is hairless. 112 WEED ID GUIDE FOR ONTARIO CROPS KUDZU 1 3 2 4 1 A compound leaf with three leaflets, the middle leaflet on a longer petiole 2 The hairy stem with nodal roots that anchor into the soil and allow the plant to creep along the ground 3 Seed pods 4 Kudzu climbing on corn plants in mid-October 5 The edge of a corn field where kudzu is growing and creeping into the field 5 WEED ID GUIDE FOR ONTARIO CROPS 113 TUFTED VETCH Legume (Fabaceae family) • Vicia cracca L. EPPO Code: VICCR Other Names: bird vetch SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and by spreading underground roots. Emergence: New shoots emerge from the underground roots throughout the season starting as early as late April, but emerge most frequently in late May to early June. Habitat: Tufted vetch prefers environments with little soil disturbance; therefore, is most often found in no-till or minimum-till cropping systems , but also in pastures, fence lines and orchards. Competitiveness: Tufted vetch has caused over 30 percent yield loss in soybeans when it is not controlled prior to planting. Its impact on soybean yield is reduced significantly if this plant emerges well after soybean emergence. When allowed to grow in cereals, it negatively affects harvesting efficiency. IDENTIFICATION CLUES Young plant First leaves: First leaves appear in alternate orientation of composite leaves, which are made up of a few pairs of opposite leaflets (typically 1–6). Mature leaves: Mature leaves appear the same as first leaves, but with more pairs of opposite leaflets. Leaves also have a tendril at the end, which helps the plant wrap around other plants and objects. Mature plant Stems: Tufted vetch stems are creeping and much branched. As they spread, they wrap around other plants and objects. Flowers: Tufted vetch produces several violet to purplish flowers, which are crowded to one side of a long bare stalk. The flowers appear from June to late autumn. Seeds: Round and dull black in colour, tufted vetch seeds are enclosed in a seedpod reminiscent of pea. Roots: Spreading horizontal roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Hairy vetch … tufted vetch is a perennial and has smaller seedpods than hairy vetch. The differences are not easy to spot, though. The biggest clue is that hairy vetch is a cover crop that is grown on purpose, so it should be more uniform than the patchy tufted vetch. 114 WEED ID GUIDE FOR ONTARIO CROPS TUFTED VETCH 1 4 2 5 1 A newly-emerged plant from underground rootstalk during early May 2 Pinnately compound leaves made up of several pairs of leaflets 3 A close up of the 30 or more violet to purplish flowers that are crowded to one side of a long, bare stalk 4 Flowering plants competing with soybeans in July 5 The pea-like seedpod of tufted vetch 3 WEED ID GUIDE FOR ONTARIO CROPS 115 CLEAVERS Madder (Rubiaceae family) • Galium aparine L. EPPO Code: GALAP Other Names: catchweed bedstraw, goose-grass, grip grass, scratch-grass, spring cleavers SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Cleavers emerges throughout the spring, summer and fall. Seemingly, though, fall is the most common time for emergence in cultivated fields. Habitat: Cleavers lives in many environments, but thrives in relatively dry, sunny areas. It does not, however, tolerate shade. Competitiveness: Cleavers causes cereal crops to lodge and reduces harvesting efficiency. Yield losses in cereals have ranged from 30–60 percent. IDENTIFICATION CLUES Seedling Cotyledons: Egg shaped on prominent petioles with a rough texture; the tip is indented. First leaves: Cleavers’ first leaves appear in whorls with three or more leaf blades. Mature leaves: Mature leaves appear in whorls of 6–8 narrow leaf blades, each with a pointed tip and rough to the touch. Mature plant Stem: Cleavers’ stem is weak, long and square, with short, downward and backwards pointing firm, hair-like curved bristles. Flowers: They are very small and clustered in groups of 1–5; they are quickly replaced by small, spherical fruit. The plant flowers from May to August. Roots: Fibrous, creeping and usually with a reddish colour. OFTEN MISTAKEN FOR I know it’s NOT … because … Smooth bedstraw … cleavers has a very coarse texture and will stick to clothing. Smooth bedstraw, on the other hand, is hairless and smooth to the touch. 116 WEED ID GUIDE FOR ONTARIO CROPS CLEAVERS 1 3 2 1 A young plant in winter wheat during early May 2 An older plant with the coarsefeeling, square stem and whorled leaves 4 3 A close up of the leaf whorls 4 A pulled plant showing the fibrous root 5 The small, spherical fruit 5 WEED ID GUIDE FOR ONTARIO CROPS 117 SMOOTH BEDSTRAW Madder (Rubiaceae family) • Galium mollugo L. EPPO Code: GALMO Other Names: cleaver, baby’s breath, white bedstraw, wild madder SPECIES INFORMATION Lifecycle: Perennial Propagation: Smooth bedstraw reproduces by seed and by spreading underground rhizomes. Emergence: Germination occurs both in the fall and in the spring, but most seedlings emerge in the spring. Habitat: Smooth bedstraw prefers moist and cool temperate habitats. It is most commonly found invading pastures and forages crops. While it is distributed across the province, smooth bedstraw is mostly found in Northeastern Ontario and in the Golden Horseshoe region. Competitiveness: Smooth bedstraw strongly competes with forage and pasture crops. IDENTIFICATION CLUES Seedling Cotyledons: Oblong, with a distinct stalk and an indentation at the apex. Leaves First leaves: Produced in whorls with three or more leaf blades. Mature leaves: Mature leaves appear in whorls of 6–8 narrow leaf blades, each with a pointed tip. Leaves at this stage are smooth to the touch. The whorled leaves are much smaller than those of cleavers. Mature plant Stem: Slender, smooth and soft, smooth bedstraw’s stem is erect at first, but becomes much more branched as the plant grows, often smothering out surrounding vegetation. Flowers: The flowers are small and contain four white petals. They sit on top of a small, round ovary, which develops into fruit that produces two seeds. Seeds: Seeds are small, about 1–1.5 mm in length, roundish to kidney shaped and grayishbrown in colour. Roots: Fibrous root system attached to spreading underground rhizomes. OFTEN MISTAKEN FOR I know it’s NOT … because … Cleavers … smooth bedstraw is hairless and smooth to the touch whereas cleavers are coarse textured and will stick to clothing 118 WEED ID GUIDE FOR ONTARIO CROPS SMOOTH BEDSTRAW 4 1 5 2 1 Seedling with orbicular cotyledon and whorl of four leaves 2 Older leaves with whorls of 6–8 leaves 3 A large patch invading a hayfield in Northeastern Ontario during mid-June 4 Flowering plants along a fencerow near Wellandport, Ontario, during mid-June 5 A close up of several white, fourpetalled flowers with the round seedpods, each producing two seeds 3 WEED ID GUIDE FOR ONTARIO CROPS 119 VELVETLEAF Mallow (Malvaceae family) • Abutilon theophrasti Medik. EPPO Code: ABUTH Other Names: butterprint, elephant ear, Indian mallow, pie-marker SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Typically, velvetleaf emerges just before and after corn and soybean planting. It is not uncommon, however, to see new seedlings emerge into the summer months. Habitat: While velvetleaf is found throughout Ontario, it is most prominent in southern Ontario. Most commonly, it grows in row crops like corn, soybeans and edible beans. Competitiveness: Agriculture and Agri-Food Canada research has shown that velvetleaf densities of 20,000 plants/ac can result in a 15 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Seedlings Cotyledons: Orbicular with long petiole and numerous short hairs. Leaves: The stem leaves of velvetleaf are alternate, heart shaped with a pointed apex, and extremely soft and “velvety” to the touch; leaf margins are round-toothed. Mature plant Stem: Velvetleaf’s stem is erect, 1–2 m tall, and covered with numerous soft hairs that give it a “velvety” feel. The stem is branched near the top of the plant. Flowers: Velvetleaf flowers are yellow, but can sometimes appear orange especially when closed. Flowers have five petals and five sepals. Seeds: Enclosed in a circular seedpod which is a cluster of of 12–15 sections (mericarps), which are green at first and turn black at maturity. They persist on leafless stems at the end of the season. Roots: Taproot OFTEN MISTAKEN FOR Velvetleaf is a very distinctive plant that is rarely confused with anything else, mainly because of its soft “velvety” feel, heart-shaped leaves and five, yellow-petaled flowers. 120 WEED ID GUIDE FOR ONTARIO CROPS VELVETLEAF 3 1 2 1 Newly emerged seedlings with orbicular shaped cotyledons 2 A young plant with numerous velvety, heart-shaped leaves 4 3 The smooth stem of velvetleaf with numerous soft hairs 4 Five-petalled, yellow flowers that turn into green seedpods 5 A mature seedpod with the circular cluster of seeds 5 WEED ID GUIDE FOR ONTARIO CROPS 121 FLOWER-OF-AN-HOUR Mallow (Malvaceae family) • Hibiscus trionum L. EPPO Code: HIBTR Other Names: Venice mallow SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Flower-of-an-hour requires warmer soil temperatures to germinate; therefore, it typically emerges in late spring to early summer. Flower-of-an-hour germinates poorly when close to the soil’s surface. Habitat: Flower-of-an-hour is common in row crops, waste places and open fields mostly in southern Ontario. It establishes in all types of soil. Competitiveness: Little data exists on the competitiveness of this species, but one can assume that its competitiveness is similar to its relative, velvetleaf. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular with a very long stalk and prominent veins. First leaves: Flower-of-an-hour’s first leaf is circular, flat, and rounded with a wavy margin. Its second leaf looks similar, but with toothed margins. Mature leaves: The mature leaves of flower-of-an-hour have an alternate-leaf orientation. They are three-parted, and each division is deeply lobed. Mature plant Stems: In its early stages of growth, flower-of-an-hour’s stem is erect. As it matures, the stem branches out and spreads. Due to the presence of coarse, whisker-like hair, the plant is somewhat fuzzy looking. Flowers: Flowers have pale yellow or white petals with purple-brown centres that are 2–4 cm wide. They emerge from a coarsely hairy calyx with prominent purple veins and a ring of hairy bracts. This plant species flowers from July to late autumn. Seeds: Kidney- or V-shaped, with a rough surface and brown to grayish black colour, 2 mm long. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Velvetleaf seedling … the leaves of velvetleaf are heart-shaped, whereas flower-of-an-hour has leaves that are lobed and three-parted. 122 WEED ID GUIDE FOR ONTARIO CROPS FLOWER-OF-AN-HOUR 1 3 2 1 A seedling with its orbicular-shaped cotyledons and leaves with toothed margins 4 2 A group of young plants starting to show the mature deeply threeparted leaves 3 A pre-bloom plant with the mature, three-parted leaves that are deeply lobed 4 A pre-bloom plant showing the distinctively hairy calyx with prominent purplish veins and the ring of hairy bracts below the calyx 5 A flower with its pale yellow or white petals and purple-brown centre 5 WEED ID GUIDE FOR ONTARIO CROPS 123 COMMON MALLOW Mallow (Malvaceae family) • Malva neglecta Wallr. EPPO Code: MALNE Other Names: garden mallow, cheeses SPECIES INFORMATION Lifecycle: Annual, biennial or short-term perennial. Propagation: Reproduces by seed. Emergence: While common mallow can germinate and emerge at any time throughout the growing season, more often than not, it is one of the first species to emerge in spring. Habitat: Common mallow is common in eastern Canada. It grows predominantly on the borders of fields, along roadsides, and in lawns and gardens. Increasingly, it is being found in minimum-till cropping systems. Competitiveness: Since it rarely emerges in a competitive crop, little to no data exists on the competiveness of this species. In cases where the species exists in the field prior to planting, it can affect crop establishment. It should, therefore, be controlled before planting begins. IDENTIFICATION CLUES Seedling Cotyledons: Spade-shaped with a heart-shaped base, prominent with veins and a long stalk. First leaves: The first leaves of common mallow are kidney-shaped, have shallow-toothed margins and grow on a long stalk. Mature leaves: Mature leaves are alternate. They are long-stalked, green to purple in colour, shallow toothed and lobed. Leaf blades are round or kidney-shaped with a heart-shaped base. Mature plant Stem: The stem of common mallow is branched and hairy. It can be erect or trail on the ground. Flowers: The flowers of common mallow are 1–1.5 cm wide and have five white to pinkish petals. The species flowers from June until late autumn. Fruit: The fruit of common mallow has a circle or “section” of 12–14 seeds. Each section has flat sides, but a rounded back, and is finely hairy and contains one brown seed. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Round-leaved mallow … common mallow is more abundant than round-leaved mallow but is otherwise hard to differentiate. Round-leaved mallow has smaller petals and the fruit sections have a flat back. Ground ivy … has opposite leaves with rounded teeth and produces a rancid, mint-like odour when crushed. In contrast, common mallow has alternate, kidney-shaped leaves with pointed teeth. 124 WEED ID GUIDE FOR ONTARIO CROPS COMMON MALLOW 4 1 5 2 1 A seedling with its spade-shaped cotyledons with whitish veins 2 A young seedling plant with a round leaf that has shallow-toothed and lobed margins 3 An example of a biennial or shortlived perennial plant in a wheat field. Although.this image was taken in April, the plant had clearly germinated the previous year. 4 A close-up of a round, kidneyshaped leaf with shallow-toothed and lobed margins along with a five-petal, white flower 3 5 A whitish-pink flower that is in the process of opening, making it difficult to see the five petals WEED ID GUIDE FOR ONTARIO CROPS 125 COMMON MILKWEED Milkweed family (Asclepiadaceae family) • Asclepias syriaca L. EPPO Code: ASCSY Other Names: silkweed, milkweed SPECIES INFORMATION Lifecycle: Perennial Propagation: Common milkweed reproduces by seed and horizontally spreading roots that produce new leafy stems. Emergence: The shoots emerge in May-June from underground root buds. After dispersal the seeds generally need a season before they germinate at a higher frequency. However, provided the soil temperature is warm enough common milkweed seeds can certainly germinate once dispersed. Seed has also been observed germinating after multiple years in storage. Habitat: Milkweed is found most frequently in open areas, especially along roadsides, fencerows and rivers, and in rangeland and cultivated fields. It is rarely found in woodlots and forested areas. Competitiveness: When competing with 12 milkweed shoots/m2 yield losses of 47 percent have been observed (Yenish and Durgan, 1997). Risk of Livestock Poisoning: Generally, the risk of livestock poisoning is low because milkweed is unpalatable and usually only consumed when no other preferred vegetation is available (Mitch, 1993). However, the primary toxins are cardiac glycosides that cause gastrointestinal, respiratory and cardiac problems that can lead to death if enough plant material is consumed (Shane, MSU). The toxicity of milkweed is not diminished when the plants are dried down (Shane, MSU). IDENTIFICATION CLUES Seedling Cotyledons: Oval First leaves: Opposite and oblong, the first leaves of common milkweed are dark green, waxy and have a prominent white mid-vein. Mature leaves: Common milkweed’s mature leaves are similar to its younger leaves in terms of shape and mid-vein, but have more wavy margins and an underside that is densely hairy. Mature plant Stems: The stem of common milkweed is erect, unbranched, hollow and covered in short hairs that resembles peach fuzz. The plant exudes a milky white juice when leaf petioles are torn off. Flowers: Common milkweed’s flowers have a round cluster of several five-petaled flowers that are pinkish white to purple. The flowers emit a pleasant fragrance and will eventually form teardrop shaped-seed pods. Seeds: Its seeds are brown, flat, oval and grow to be 6–10 mm long. The seeds are attached to a tuft of silky white hairs (fluff) that aids in wind dispersal with longer tufts of hair, which allow the seed to travel longer distances. In field trials with wind speeds gusting to 24 kph, milkweed seed traveled as far as 43 metres. Roots: Common milkweed’s roots are thick and fleshy, white rhizomes that are very difficult to pull out of the soil. When pulled they often break. OFTEN MISTAKEN FOR I know it’s NOT … because … Hemp dogbane … milkweed has larger leaves, a green fuzzy stem and an erect unbranched stem, while hemp dogbane has smaller leaves, is branched, and has a reddish, hairless stem. 126 WEED ID GUIDE FOR ONTARIO CROPS COMMON MILKWEED 1 3 2 1 Milkweed shoots emerging in a soybean field during the first week of June 4 2 Sticky white milk exudes from milkweed when plant tissue is torn 3 A patch of milkweed at the prebloom stage in a field of flowering flax 4 A flowering plant 5 An open seedpod reveals numerous brown seeds, each with silky white hairs 5 WEED ID GUIDE FOR ONTARIO CROPS 127 DOG STRANGLING VINE Milkweed family (Asclepiadaceae family) • Vincetoxicum rossicum (Kleopow) Barbar. EPPO Code: VNCRO Other Names: swallow-wort SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed and by sprouting from short rhizome if plant is damaged. Emergence: Dog strangling vine’s shoots will emerge from May to June from underground root buds. The seeds generally need a season after dispersal before they germinate at a higher frequency, but they certainly can germinate once dispersed provided the soil temperature is warm enough. Seed has been observed to germinate after multiple years in storage. Habitat: Dog strangling vine grows predominately in central Ontario in woodlots, ravines, and waste areas, as well as along hillsides and fence lines. More recently, however, it has also been found in southern and eastern Ontario. Competitiveness: Dog strangling vine is an aggressively growing plant that will out-compete many other species. Once established, it is very difficult to control. Risk of Livestock Poisoning: Livestock generally avoid consuming this species on pastureland, unless there is little other vegetation available. A review of livestock poisoning literature by DiTommaso et al. (2005), concluded that “sufficient amounts of toxin(s) are present to consider the plant dangerous for grazing livestock and wildlife, especially if other better quality forage is limited.” IDENTIFICATION CLUES Seedling Cotyledons: Oblong, with a pointed to rounded apex, about 5–7 mm long. Young leaves: Dog strangling vine’s first leaves are opposite, oval to oblong and dark green with a pointed tip. They are also hairless and have entire margins. Mature leaves: Appear similar to younger leaves in terms of shape, but are usually larger. Mature plant Stems: Just as its name implies, dog strangling vine’s stem is vine-like, twining and either herbaceous or with a woody base. Flowers: Its flowers are maroon to pinkish with five petals, which gives it a star-shaped appearance. It has a lobed and darker maroon corona. Dog strangling vine will flower from June to September. Flowers turn to slender seed pods. Seeds: Dog strangling vine’s seeds are flat, brown, egg-shaped and attached to long white silky “fluff” that aids in wind dispersal. Roots: Crown root with short underground spreading rhizomes. OFTEN MISTAKEN FOR I know it’s NOT … because … Black dog-strangling vine … it is near impossible to tell the difference between the two species during vegetative growth, but at flowering black dog-strangling vine has dark purple to black flowers with pubescence on the inner surface while dog-strangling vine has hairless, maroon to light pink petals. Dog strangling vine is more common in Ontario. 128 WEED ID GUIDE FOR ONTARIO CROPS DOG STRANGLING VINE 1 3 2 1 Vegetative growth arising from crown roots in early June 2 A flowering plant and opposite leaf orientation 4 3 Maroon-coloured, star-shaped flowers with slender pods during late June 4 A close-up of the star-shaped maroon flowers with darker maroon, lobed coronas 5 Flowering plants along a nature trail during mid-June in Waterloo County 5 WEED ID GUIDE FOR ONTARIO CROPS 129 HEMP-NETTLE Mint (Lamiaceae family) • Galeopsis tetrahit L. EPPO Code: GAETE Other Names: bee nettle, dog nettle, flowering nettle SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Hemp-nettle is a very early germinating species. Habitat: It can be found throughout the province, but is most commonly found in cereal crops in central and northern Ontario. Competitiveness: The plant’s impact is greatest on cereal crops where significant yield losses have been observed. Due to its early germination pattern, hemp-nettle is often controlled by tillage or pre-plant herbicide applications. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular with basal points (two small auricles pointing backwards) 5–15 mm long. First leaves: Oval to elongated, densely hairy with toothed margins and prominent veins. Mature leaves: Mature leaves have an opposite leaf orientation. They are oval with a “stretched out” tip, and hairy with toothed margins and prominent veins. Mature plant Stems: Hemp-nettle’s stem is erect, branched, square and covered with coarse, downwardpointing hair. Flowers: Flowers appear in dense clusters in the leaf axils, and they have irregular-shaped, pinkish white to purple petals, which make them look somewhat like miniature snapdragon flowers. Seeds: Each flower has four, egg-shaped seeds located in the base of a tubular receptacle. Roots: Taproot with branched, lateral roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Hairy galinsoga … hemp-nettle has cotyledons with basal points, a square stem and irregularshaped, pinkish-white to purple flowers compared to the round stem of hairy galinsoga with its small, yellow and white flower head. 130 WEED ID GUIDE FOR ONTARIO CROPS HEMP-NETTLE 1 4 5 1 A seedling with round cotyledons and leaves with toothed margins 2 2 A close up showing the hairy stem and leaves with rounded toothed margins 3 Opposite leaf orientation 4 Whitish-pink to pinkish-purple flowers in a dense cluster 5 Flowers become hard and very spiny at maturity 3 WEED ID GUIDE FOR ONTARIO CROPS 131 HENBIT Mint (Lamiaceae family) • Lamium amplexicaule L. EPPO Code: LAMAM Other Names: henbit deadnettle SPECIES INFORMATION Lifecycle: Annual or winter annual Propagation: Reproduces by seed Emergence: Henbit germinates in the fall. Seedlings can appear in early spring, Habitat: Native to Eurasia and North Africa, henbit is now common in southern Ontario’s waste and water areas, on roadsides and in crop lands. It is most commonly found in cereal crops. It is found less often in corn and soybeans, since the species can be managed easily prior to planting. Competitiveness: A study conducted by Purdue University identified crop yield losses as high as 38 percent in cereals. Henbit is also an alternate host for soybean cyst nematode. IDENTIFICATION CLUES Seedling Cotyledons: Oval to round, with two small lobes at the base and a long stalk. Hairless. First leaves: Circular to heart-shaped, with 2–4 indentations on each side and a long stalk; opposite leaf orientation. Mature plant Mature leaves: Mature leaves look similar to first leaves with opposite leaf orientation and circular to heart shaped and coarse rounded lobes or teeth. The lower leaves have a long stalk, but the upper leaves are sessile (stalkess) broad-based giving the impression of a single leaf wrapping the stem. Stems: Stems are square in cross-section. They appear erect, high and heavily branched near the base. As they mature, they become further erect and finely hairy. Henbit’s stem is green or purple in colour. Flowers: Small and tubular with united petals, pink to purple flowers that appear in clusters in the axils of upper leaves. Henbit flowers in spring and early summer. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Purple deadnettle … the upper leaves of deadnettle are triangular and have a purple or red tint to them. The upper leaves of henbit, however, are green, rounded and somewhat heartshaped. 132 WEED ID GUIDE FOR ONTARIO CROPS HENBIT 1 3 2 4 1 A seedling plant with its oval to round cotyledons 2 A larger plant just beginning to flower during late May 3 A close up of the opposite leaf orientation (two per node); leaves are somewhat heart shaped and have coarsely lobed margins 4 The pinkish-purple flower with two lobes at the bottom 5 A close up of the flower 5 WEED ID GUIDE FOR ONTARIO CROPS 133 PURPLE DEADNETTLE Mint (Lamiaceae family) • Lamium purpureum L. EPPO Code: LAMPU Other Names: red dead-nettle, red nettle, purple archangel SPECIES INFORMATION Lifecycle: Winter annual. Propagation: Reproduces by seed. Emergence: Germinates in the fall. Habitat: Native to Eurasia, purple deadnettle is now common in North America. It is found in fields, gardens and turf grass. Competitiveness: Similar to henbit, purple deadnettle is also an alternate host for soybean cyst nematode. IDENTIFICATION CLUES Seedling Cotyledons: Oval to round, with two small lobes at the base and a long stalk. Hairless. First leaves: The first leaves have an opposite orientation. They appear on short stalks and are triangular to heart-shaped with rounded teeth. The leaf surface is hairy. Mature plant Mature leaves: They grow in an opposite orientation; the upper leaves are heart-shaped, densely covered with hairs and petiolated; as they reach the top of the stems, the leaves are smaller, more overlapped and develop a red or purple tinge. Opposite leaf orientation; leaves grow on stalks and are circular to heart-shaped. Stem: Branched and square in cross-section. Flowers: Pink to purple in colour, purple deadnettle’s flowers appear as whorls in the upper leaf axils. The plant flowers in early spring. Roots: Fibrous taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Henbit … although henbit and deadnettle both have square stems and flower in the early spring, the upper leaves of deadnettle usually have a red to purple tinge to them, are triangular and grow on leaf stalks, whereas henbit’s leaves are green and lack stalks. 134 WEED ID GUIDE FOR ONTARIO CROPS PURPLE DEADNETTLE 1 4 2 5 1 Purple deadnettle prior to flowering in late April 2 The square stem of purple deadnettle 3 A closer look at the square stem 4 A flowering plant 5 Dense patches in wheat stubble slated for corn planting in mid-May 3 WEED ID GUIDE FOR ONTARIO CROPS 135 HEDGE BINDWEED Morning-glory family (Convolvulaceae family) • Calystegia sepium (L.) R. Br. EPPO Code: CAGSE Other Names: hedge morning-glory, large morning-glory, wild morning-glory SPECIES INFORMATION Lifecycle: Perennial Propagation: Hedge bindweed reproduces by seed and by rhizomes that can persist up to 60 cm below the soil surface. Emergence: The plant requires warmer soil temperatures to germinate; therefore, it typically emerges in late spring to early summer. Germination is poor where seeds are found close to the soil surface. Habitat: Hedge bindweed is a native plant in southwestern Ontario. It is generally found in edges of woods, waste places, fence rows and open fields and occasionally in crops. It establishes in all types of soil. Competitiveness: The creeping and twining nature of hedge bindweed can lead to significant yield losses in various crops, which reduces harvesting efficiency. IDENTIFICATION CLUES Seedling Cotyledons: Square with prominent whitish veins, indented at the apex and base. First leaves: Oval leaves with two large basal lobes. Mature leaves: Triangular or arrow shaped with two deep basal lobes and a pointed tip (apex). Mature plant Stems: The stem of hedge bindweed is hairless and smooth to the touch. Its twining and curling nature means that it is often found wrapped around nearby structures. Flowers: Hedge bindweed has round, morning glory-like flowers that are typically 8–10 cm in diameter, or about twice to three times the size of field bindweed. Often, the flowers are white, but they can also be pinkish-white. The base of the flower has two large bracts that hide the calyx. Flowers are produced from May to September. Seeds: Hedge bindweed’s seeds are small, growing to about 5mm in length. They are egg shaped and dark brown to black in colour. Roots: The plant has an underground root and rhizome system that has the ability to spread extensively. Its roots and rhizomes are whitish in colour. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild buckwheat … wild buckwheat has an ocrea that surrounds the leaf stem at each node and it lacks the round showy morning-glory-like flowers of hedge bindweed. Field bindweed…hedge bindweed’s flowers are two to three times the size of field bindweed’s and have two large bracts that cover the calyx. Its leaves have a pointed tip (apex) and two deep basal lobes while field bindweed has a rounded apex and narrow lobes. They are also much larger in comparison with the smaller leaves of field bindweed. 136 WEED ID GUIDE FOR ONTARIO CROPS HEDGE BINDWEED 3 1 4 1 The triangular-shaped leaves with two deep basal lobes and the pointed tip 2 A flowering patch in mid-August with stems climbing up other plants 3 Hedge bindweed leaf (left) compared to a field bindweed leaf (right) 2 4 A hedge bindweed flower (left) compared to a field bindweed flower (right) WEED ID GUIDE FOR ONTARIO CROPS 137 FIELD BINDWEED Morning-glory family (Convolvulaceae family) • Convolvulus arvensis L. EPPO Code: CONAR Other Names: European bindweed, small-flowered morning glory, wild morning glory SPECIES INFORMATION Lifecycle: Perennial Propagation: Field bindweed reproduces by seed and an extensive network of persistent roots and rhizomes. Emergence: The plant requires warmer soil temperatures in order to germinate. As a result, it typically emerges in late spring to early summer. When seeds are located close to the soil’s surface, germination is poor. Habitat: Field bindweed is most commonly found in southwestern Ontario in row crops, waste places and open fields. It establishes in all types of soil. Competitiveness: The creeping and twining nature of field bindweed can result in significant yield losses in various crops. It can also reduce harvesting efficiency. IDENTIFICATION CLUES Seedling Cotyledons: Square with prominent whitish veins. First leaves: Oval leaves with two basal lobes. Mature leaves: Alternate, triangular or arrow shaped with two basal lobes on short and long stalks. Mature plant Stems: Field bindweed’s stem is smooth to the touch, but finely haired. The stem often twines and curls, wrapping itself around nearby structures. Flowers: Field bindweed has round, morning glory-like flowers that range in colour from white to pink to pinkish-white. Seeds: The plant’s seeds are small (about 3 mm in length), pear shaped and grayish-black with tiny bumps. Roots: Whitish and extensively spreading underground root system. OFTEN MISTAKEN FOR I know it’s NOT … because … Wild buckwheat … wild buckwheat has an ocrea that surrounds the leaf stem at each node and lacks the round showy morning glory-like flowers of field bindweed. Hedge bindweed … field bindweed’s flowers are much smaller (½ to ¹⁄³) than those of hedge bindweed. The leaves have a rounded tip (apex) and two short, pointed lobes compared to the pointed tip and large basal lobes of hedge bindweed. They are also much smaller in comparison with the larger leaves of hedge bindweed 138 WEED ID GUIDE FOR ONTARIO CROPS FIELD BINDWEED 1 3 2 1 Leaves emerging from its extensive underground roots in early June 2 Bindweed growing in mid-June will soon start to climb the neighboring corn plants 4 3 The alternate arrow-shaped leaves 4 The curling or twining stem and arrow-shaped leaves of a mature plant 5 The round, pinkish-white flowers of field bindweed 5 WEED ID GUIDE FOR ONTARIO CROPS 139 GARLIC MUSTARD Mustard (Brassicaceae family) • Alliaria petiolata (M. Bieb.) Cavara & Grande EPPO Code: ALAPE Other Names: stinky mustard SPECIES INFORMATION Life cycle: Annual, winter annual or biennial. Propagation: Reproduces by seeds, which typically remain dormant until at least one year after dispersal. Emergence: Seeds germinate in the early spring. Habitat: Garlic mustard is found throughout Ontario, typically in woodlots, on the edge of woodlots and in waste areas. This species is rarely found in cultivated fields. Competitiveness: Although garlic mustard is edible and contains a higher value of vitamin C on a per-weight basis than oranges, it is mainly viewed as an invasive weed that replaces native vegetation (Cavers et al., 1979). IDENTIFICATION CLUES Seedlings Cotyledons: Elongated to oblong. Leaves First leaves: Garlic mustard’s first leaves grow in a basal rosette, are kidney shaped with a broad rounded tip, and have margins with shallow rounded teeth. The leaves emit a garliclike odour when tissue is crushed. Mature leaves: Stem leaves are alternate, heart-shaped to triangular in shape, with more coarsely toothed margins. They also emit the same garlic-like odour. Mature plant Stem: Garlic mustard’s stem is erect and smooth, and reaches almost one metre in height. Flowers: small, white, 4-petaled flowers are grouped in small clusters at the tip of the plant or in leaf axils. They give rise to the characteristic long and slender seed pods of the mustard family. Seeds: Small, round and black, garlic mustard’s seeds are 3 mm in diameter and emit a garliclike odour. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Stinkweed … the basal leaves of garlic mustard are kidney-shaped with broad rounded tips and round toothed margins, while the leaves of stinkweed are elongated and have wavytoothed margins. 140 WEED ID GUIDE FOR ONTARIO CROPS GARLIC MUSTARD 1 2 4 1 A young seedling plant in the spring 2 A rosette in the fall with its kidneyshaped leaves 3 3 A cluster of small white 4-petaled flowers with long slender seed pods above the triangular-shaped stem leaves 4 A cluster of flowering plants in a woodlot during June WEED ID GUIDE FOR ONTARIO CROPS 141 SHEPHERD’S-PURSE Mustard (Brassicaceae family) • Capsella bursa-pastoris (L.) Medik. EPPO Code: CAPBP Other Names: poverty weed, beggar tick, shepherd’s heart, pick purse SPECIES INFORMATION Lifecycle: Winter annual or biennial. Propagation: Reproduces by seed. Emergence: Early spring. Habitat: Native to Europe. Found throughout Ontario in fields, gardens, roadsides and waste areas. Most commonly found in winter cereals. Competitiveness: In Sweden, shepherd's purse is one of the most detrimental species affecting winter cereal yields (Milberg and Hallgren, 2004). IDENTIFICATION CLUES Seedling Cotyledons: Oblong small (3–6 mm long) with very short petiole. Leaves First leaves: Rounded to oval with entire margins and forming a rosette. Mature leaves: Arranged as a rosette. Leaves generally deeply divided, covered with star shaped hairs on surface that are most visible with a magnifying glass. Mature plant Stem: Erect and with few branches, 10–60 cm tall. Flowers: Small cluster of white flowers each with 4 small narrower sepals and 4 large broad petals arranged in a cross formation; seedpods (silicles) are heart-shaped. Seeds: Oblong, 1 mm long and orange to reddish brown in colour. Roots: Taproot with secondary fibrous roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Dandelion … Shepherd’s-purse does not excrete a milky juice when its leaf tissue is torn; its mature rosette leaves are more deeply divided and the leaf surface covered in small, starshaped hairs. Stinkweed … Shepherd’s-purse lacks the “chive-like” odour of stinkweed; its leaves are deeply divided and with a surface covered in small, star-shaped hairs compared to the slightly toothed and smooth leaf surface of stinkweed. 142 WEED ID GUIDE FOR ONTARIO CROPS SHEPHERD’S-PURSE 1 3 2 4 1 A seedling rosette plant with a mix of leaves having deeply divided and entire margins 2 Mature leaves contain numerous star-shaped hairs that are easiest to spot under a magnifying lens 3 A pre-bolt seedling rosette with all leaves being deeply divided 4 A flowering plant with its small white flowers that turn into heartshaped seed pods 5 Close-up of the heart-shaped seed pod containing numerous small orange-brown oblong seeds 5 WEED ID GUIDE FOR ONTARIO CROPS 143 FLIXWEED Mustard (Brassicaceae family) • Descurainia sophia (L.) Webb ex Prantl EPPO Code: DESSO Other names: tansy mustard SPECIES INFORMATION Lifecycle: Winter annual or biennial Propagation: Reproduces by seed Emergence: Early spring Habitat: Native to Europe; found throughout Ontario in fields, gardens, roadsides and waste areas. Competitiveness: Competitive in crop plants, can crowd and reduce yields. IDENTIFICATION CLUES Leaves Cotyledons: Elongated to oblong or club shaped, base tapering into a long stalk, 10–12 mm long. First leaves: arranged in tight rosette, three-lobed initially, then further divided. Mature leaves: Alternate leaf orientation; narrow, long and lacey in appearance with 2–3 divisions and fine hairs; appear grayish-green. Mature plant Stem: Branched, grayish-green, erect and covered in fine, “star-like” hairs; 30–100 cm in height. Flowers: Individually very small and clustered on long stalks at the ends of stems and branches; green to pale yellow; flowers in the summer months. Seeds: Seedpods on slender stalks, curve upwards and almost parallel to the stem; seeds are bright orange. Helpful tip Stems and lacey-looking leaves of flixweed are a gray-green colour because of a dense covering of fine, branched “star-like” hairs. OFTEN MISTAKEN FOR Seedling flixweed resembles and are often mistaken for other plants with finely divided leaves. I know it’s NOT … because … Common ragweed ... Flixweed has elongated to oblong cotyledons compared with common ragweed’s round ones. Flixweed has round grayish-green stems compared to the flat, green stems of common ragweed at the juvenile stage. Flixweed leaves are more finely divided and the flowers are yellow compared to common ragweed’s green flowers. Wild carrot ... Flixweed’s cotyledons are much broader than those of wild carrot. Wild carrot leaves are more finely divided than flixweed and will smell of carrots when crushed. Flixweed has yellow flowers compared to white for wild carrot. Biennial wormwood ... The stems of biennial wormwood are green, flat and hairless. Flixweed has rounded leaf edges while biennial wormwood has sharp leaf edges. 144 WEED ID GUIDE FOR ONTARIO CROPS FLIXWEED 1 4 2 5 1 A seedling flixweed plant during the first week of May 2 A flixweed plant prior to bolting during the first week of May having germinated the previous fall 3 The grayish-green stem with several hairs and the finely divided leaves 4 The typical yellow raceme that plants from the mustard family have along with the long narrow seedpods below 5 Flixweed infesting a soybean crop 3 WEED ID GUIDE FOR ONTARIO CROPS 145 WHITLOWGRASS Whitlowgrass (Brassicaceae family) • Draba verna L. EPPO Code: ERPVE Other Names: spring whitlowgrass SPECIES INFORMATION Lifecycle: Annual, winter annual. Propagation: Reproduces by seed. Emergence: Whitlowgrass emerges in the fall or early spring and usually completes its life cycle by mid-May. Habitat: Although it is most often found in cereal crops, whitlowgrass has also been found in soybean and corn crops. Recent surveys found it to be most prominent in south-central Ontario. Competitiveness: Whitlowgrass does not impact yield, even in cereal crops where it is often found. IDENTIFICATION CLUES Seedlings Cotyledons: very small (1 mm), round to club shaped with a short petiole, rapidly masked by leaves. First leaves: The plant’s first leaves appear as a basal rosette of oblong leaves that are covered in small, fine hairs. Mature leaves: Similar to first leaves. Mature plant Stem: Whitlowgrass does not have stem leaves. The bolting, wiry stem that rises from the basal rosette does, however, produce several small, white flowers. Flowers: The flowers of whitlowgrass are extremely small and have a yellow centre. The flower has four white petals that are so deeply lobed as to give it the appearance of having eight petals instead. Seeds: Seedpods are flat, football shaped and about 3 mm long. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Shepherd’s purse … whitlowgrass flowers much earlier than shepherd’s purse, has a much smaller basal rosette (about the size of a dime) and the seedpods are football shaped in comparison to the heart-shaped seedpods of shepherd’s purse. Canada fleabane …. whitlowgrass has narrower basal leaf blades that are much hairier than those of Canada fleabane. 146 WEED ID GUIDE FOR ONTARIO CROPS WHITLOWGRASS 1 3 2 4 1 Flowering plant in a winter wheat field during early May 2 Close up of a rosette with hairy, oblong, basal leaves 3 A plant with the football-shaped seedpods in mid-April 4 A cluster of flowering plants during early May 5 Heavy infestation in a winter wheat crop during late April 5 WEED ID GUIDE FOR ONTARIO CROPS 147 FIELD PEPPERGRASS Mustard (Brassicaceae family) • Lepidium campestre (L.) W.T. Aiton EPPO Code: LEPCA Other Names: field pepperweed, pepperweed SPECIES INFORMATION Lifecycle: Annual or winter annual Propagation: Reproduces by seed Emergence: Typically, field peppergrass germinates and emerges in the fall or early part of spring. Habitat: Field peppergrass is predominately found in orchards, nurseries and waste areas in southern Ontario. It is rarely found in cultivated fields. Competitiveness: Little published data exists and results are varied. Swan (1971) indicated yield losses in winter wheat as high as 45%, while more recently a Swedish study evaluating peppergrass as an oil crop observed increased Barley yields when field peppergrass was under-seeded (Merker et al., 2010) IDENTIFICATION CLUES Seedling Cotyledons: Club-shaped to oval, with a long stalk, 12–15 mm long Young leaves: The plant’s first leaves emerge as a basal rosette, oval with entire margins and on long petioles. Mature leaves: Rosette leaves become wavy-toothed to deeply-lobed margins. The stem leaves are alternate, arrow shaped and clasp the stem. Margins are entire to slightly toothed. Mature plant Stem: The stem is erect, grows 10–60 cm tall and has short hairs. It is much branched near the top. Flowers: Field peppergrass produces clusters of small, white four-petal flowers. Fruit: Seedpods are numerous, flat and round. The top of the seedpod has a small notch; each contains two small, rust-coloured to brown seeds. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Stinkweed … stinkweed is hairless as compared to the rough-textured field peppergrass that is densely htairy. Field peppergrass does not produce an odour when plant tissue is crushed. 148 WEED ID GUIDE FOR ONTARIO CROPS FIELD PEPPERGRASS 1 2 4 1 The basal rosette with oval leaves having a rounded apex 3 2 An older rosette with leaves that are deeply lobed 3 A flowering plant with seedpods 4 A patch of flowering plants in early June WEED ID GUIDE FOR ONTARIO CROPS 149 WILD MUSTARD Mustard (Brassicaceae family) • Sinapis arvensis L. EPPO Code: SINAR Other Names: common mustard, field mustard, mustard, kale, charlock, yellow mustard, herrick SPECIES INFORMATION Lifecycle: Annual, winter annual Propagation: Reproduces by seed Emergence: One of the first broadleaf weed species to emerge in the spring Habitat: Wild mustard is most often found in winter cereal crops, particularly in central and southern Ontario. It is rarely found in spring planted crops since its life cycle is initiated very early in the spring. Competitiveness: Agriculture and Agri-Food Canada research has shown that wild mustard densities of 20,000 plants/ac can result in an 18–20 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Seedling Cotyledons: Kidney shaped First leaves: Hairy, ovate with wavy toothed margins Mature leaves: Wild mustard’s mature leaves are hairy, coarse to the touch, elongated, and lobed with wavy toothed margins. Mature plant Stem: Wild mustard’s stem is erect, reaches almost 1 m in height, hairy and branched. Flowers: The plant has a small cluster of yellow flowers each with four small, narrow sepals and four large, broad petals arranged in a cross formation. Seeds: Its seeds are small, round and black to purplish-black. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Volunteer canola … wild mustard is relatively hairy and coarse to the touch and its leaves are supported by short stalks that are lacking in canola. Most volunteer canola will be tolerant to the herbicide active ingredients glyphosate and glufosinate. 150 WEED ID GUIDE FOR ONTARIO CROPS WILD MUSTARD 1 4 2 5 1 Kidney-shaped cotyledons 2 A seedling plant with wavy toothed margins 3 A mature plant with numerous small yellow flowers 4 A close up of the flower with small yellow petals 5 The narrow elongated seedpod 3 WEED ID GUIDE FOR ONTARIO CROPS 151 STINKWEED Mustard (Brassicaceae family) • Thlaspi arvense L. EPPO Code: THLAR Other Names: field pennycress, pennycress, frenchweed SPECIES INFORMATION Lifecycle: Annual or winter annual. Propagation: Reproduces by seed. Emergence: Typically, stinkweed germinates and emerges in the fall or early spring. Habitat: Stinkweed is found throughout Ontario, but most commonly in winter cereal crops and much less frequently in corn, soybeans and edible beans. Competitiveness: Little to no data exists on the competitiveness of stinkweed, but one can assume that its competitiveness is similar to that of wild mustard. Stinkweed likely has very little yield impact to winter cereals, the crop that it is most often found in. The main concern with this weed is its garlic/chive like odour, which can taint milk if consumed by dairy cattle. IDENTIFICATION CLUES Seedling Cotyledons: orbicular to oblong with a very short stalk. First leaves: Stinkweed’s first leaves emerge as a basal rosette, which are oval with wavy margins and a rounded apex (tip). When its leaves are crushed, the plant gives off a distinct garlic/chive-like odour. Mature leaves: Mature leaves have an alternate leaf orientation. The leaves, which clasp the stem, are shallow to deeply toothed, have a pointed apex, and a distinct garlic/chive-like odour when crushed. Mature plant Stem: Stinkweed’s stem is erect, 10–60 cm tall, hairless and much branched near the top. Flowers: Its flowers are very small, white and grow in clusters at the end of the branches. Each flower consists of four petals. Fruit: Stinkweed seedpods are flat, round and almost penny shaped. The top of the seedpod has a deep notch, and the seedpod itself contains two compartments that house numerous small, rust-coloured seeds. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Field peppergrass … stinkweed is smooth and hairless, while field peppergrass is roughly textured and is densely hairy. Also, field peppergrass does not have a distinct odour when crushed. 152 WEED ID GUIDE FOR ONTARIO CROPS STINKWEED 1 4 5 1 Basal rosette with oval leaves that have a rounded apex and wavy margins 2 2 An older plant that has bolted from the basal rosette with more toothed margins 3 A plant prior to flowering; the mature leaves are pointed at the apex and have shallow, toothed margins 4 A flowering plant with numerous small, white, four-petal flowers growing in clusters at the end of branches 3 5 Flat, round seedpods with a deep notch at the top and two seed compartments WEED ID GUIDE FOR ONTARIO CROPS 153 JIMSONWEED* Nightshade (Solanaceae family) • Datura stramonium L. EPPO Code: DATST Other Names: thornapple, locoweed, devil’s trumpet, hell’s bells, stinkweed, prickly burr * POISONOUS WHEN CONSUMED SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: While the majority of jimsonweed seed germinate in May and June, they can germinate later in the summer as well. Habitat: Jimsonweed prefers warmer environments. For this reason, it is often found in southern Ontario around the Great Lakes. It can, however, also be found in eastern Ontario and parts of western Quebec. Competitiveness: Studies conducted in the United States by Hagood et al. (1981) showed yield losses in soybeans as high as 45 percent where crops compete with jimsonweed at densities of 44,000 plants/ac. Toxicity: All parts of jimsonweed are poisonous and should never be consumed. If accidentally consumed, seek medical attention immediately. IDENTIFICATION CLUES Leaves Cotyledons: Linear and narrow; the stem attached to cotyledons is hairy. First true leaves: First true leaves are egg-shaped , tapering to a pointed tip, have few to no lobes and a relatively long stalk. Mature leaves: Large and wide, mature leaves are usually sharply toothed or lobed and grow on stout stalks. Mature plant Stem: Jimsonweed stems are erect, stout, hollow, smooth and hairless, and have an alternate leaf arrangement. The stem branches out in the upper part. It is green to purple in colour, and has a distinct, foul odour when rubbed. It can reach 90–200 cm. Flowers: Individual flowers, which are large and funnel-shaped, and white to purple in colour, grow on the plant’s short stalks. Jimsonweed flowers from July to autumn. Fruit: The egg-shaped fruit of jimsonweed is covered with stick prickles. As it matures, the fruit splits into four segments. It eventiually turns into a hard seedpod that contains multiple black, round, flat seeds. Roots: Jimsonweed has a thick and extensively-branched taproot. OFTEN MISTAKEN FOR I know it’s NOT … because … Cocklebur … jimsonweed leaves are smooth to the touch, while the leaves of cocklebur are coarse and sandpaper-like. Also, jimsonweed has a distinct, fowl odour. 154 WEED ID GUIDE FOR ONTARIO CROPS JIMSONWEED 1 3 2 4 1 The linear cotyledons of jimsonweed 2 A young seedling with its first two, oval-shaped leaves being oval (later leaves are more deeply toothed 3 A seedling plant growing in a corn crop canopy 4 The stem, which is typically dark purple and smooth, has a foul odour when rubbed 5 Seedpods with numerous sharp spines on a mature plant 5 WEED ID GUIDE FOR ONTARIO CROPS 155 CLAMMY GROUND-CHERRY* Nightshade or potato (Solanaceae family) • Physalis heterophylla Nees. EPPO Code: PHYHE Other names: ground-cherry, hairy ground-cherry, Japanese lantern * POISONOUS WHEN CERTAIN PLANTS PARTS ARE CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Clammy ground-cherry reproduces by seed and by deeply penetrating and spreading roots. Dispersal of root fragments after cultivation will increase the spread of ground-cherry. Ontario studies demonstrate that root fragments left on the soil’s surface did not regenerate and that shallow burial of root fragments at 5 cm depths resulted in the fastest regeneration. Tillage timed at fruit dispersal results in the least regeneration of root fragments (Abdullahi and Cavers, 1997). Range and habitat: Clammy ground-cherry is most commonly found in southern Ontario, usually on well-drained coarse soils. Toxicity: Although the leaves and unripe fruit contain the solanine alkaloid, accounts of toxicity vary from “poisonous and even fatal if ingested” (Ohio State University Extension, 2015) to “cause gastroenteritis and diarrhea when ingested” (Government of Canada, 2015). The ripe fruit has been used for making preserves (Government of Canada, 2015). INDENTIFICATION CLUES Leaves Cotyledons: Elongated Young leaves: The weed’s young leaves are alternate, on a long petiole, oval, pointed at the tip and hairy. They also have entire margins. Mature leaves: Mature leaves are alternate, on long petioles, covered in sticky hairs and have wavy toothed margins. Mature plant Stem: The plant’s stem is extremely hairy, erect and grows 20–90 cm in height. It is branched at the top. Flowers: Clammy ground-cherry flowers are yellow with five petals fused together to form a trumpet-like, bell-shaped flower. Fruit: Its fruit are papery hairy and round with a pointed tip. Reminiscent of a Japanese lantern, the flower contains a small, round and green berry that turns yellow when ripe. Roots: Deeply penetrating and spreading fibrous roots OFTEN MISTAKEN FOR I know it’s NOT … because … Smooth ground-cherry … clammy ground-cherry is covered in sticky hairs while smooth groundcherry is pretty much hairless. Hairy nightshade … clammy ground-cherry originates from penetrating and spreading roots and has a yellow trumpet-like, bell-shaped flower that produces a yellow berry. Hairy nightshade, on the other hand, has a taproot, small white flowers and brown berries. 156 WEED ID GUIDE FOR ONTARIO CROPS CLAMMY GROUND-CHERRY 1 4 2 5 1 Vegetative growth originating from a regenerating root fragment 2 The alternate leaves with wavy toothed margins 3 A cluster of four, hairy and pointed calyx, one having the yellow trumpet bell shaped flower 4 A yellow flower showing the five petals that are fused together to form the trumpet-like bell shape 5 The papery Japanese lantern-like capsule that contains a round berry 3 WEED ID GUIDE FOR ONTARIO CROPS 157 SMOOTH GROUND-CHERRY* Nightshade or potato (Solanaceae family) • Physalis longifolia Nutt. EPPO Code: PHYSU Other names: longleaf groundcherry, ground-cherry, husk-tomato, Japanese lantern * POISONOUS WHEN CERTAIN PARTS ARE CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Smooth ground-cherry reproduces by seed and by deeply penetrating and spreading roots. Dispersal of root fragments after cultivation will increase its spread. Ontario studies demonstrate that root fragments left on the soil’s surface do not regenerate and that shallow burial of root fragments at 5 cm depths result in the fastest regeneration. Tillage timed at fruit dispersal results in the least regeneration of root fragments (Abdullahi and Cavers, 1997). Range and habitat: Smooth ground-cherry is most commonly found in southern Ontario, usually on well-drained coarse soils. Toxicity: Although the leaves and unripe fruit contain the solanine alkaloid, accounts of toxicity vary from “poisonous and even fatal if ingested” (Ohio State University Extension, 2015) to “cause gastroenteritis and diarrhea when ingested” (Government of Canada, 2015). The ripe fruit has been used for making preserves (Government of Canada, 2015). IDENTIFICATION CLUES Leaves Cotyledons: Elongated , wider at the base, with a medium length stalk. Young leaves: The plant’s young leaves are alternate and grow on long petioles. Leaves are oval, pointed at the tip, smooth and have entire margins. Mature leaves: Smooth ground-cherry’s mature leaves are alternate, grow on long petioles and are smooth. They have wavy toothed margins. The mature leaves of smooth groundcherry’s are not as wide as those of clammy ground-cherry. Mature plant Stem: The plant’s stem is hairless, erect and grows 20–90 cm in height. It is branched at the top. Flowers: Smooth ground-cherry has yellow flowers with five petals that are fused together to form a trumpet-like, bell-shaped flower with a purplish center. Fruit: Its flowers are papery, hairy and round with a pointed tip. Reminiscent of a Japanese lantern, the flower contains a small, round and green berry that turns yellow when ripe. Roots: Deeply penetrating and spreading fibrous roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Clammy ground-cherry … smooth ground-cherry is hairless compared to the hairy and stickyto-clammy texture of clammy ground-cherry. 158 WEED ID GUIDE FOR ONTARIO CROPS SMOOTH GROUND-CHERRY 4 1 5 1 A mature plant 2 2 A hairless mature leaf with wavy toothed margins 3 A smooth and almost hairless stem 4 The yellow flower showing the five petals that are fused together to form the trumpet-like bell shape and the dark purplish center 5 The papery Japanese lantern-like capsule contains a round berry 3 WEED ID GUIDE FOR ONTARIO CROPS 159 HORSE-NETTLE* Nightshade or potato Family (Solanaceae family) • Solanum carolinense L. EPPO Code: SOLCA Other Names: bull nettle, apple-of-sodom, wild tomato, devil’s tomato, devil’s potato, sand brier, sand burr * POISONOUS IF PLANT PARTS ARE CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Horse-nettle reproduces by seed and spreading underground rhizomes. Emergence: Its shoots begin to emerge from the overwintering rhizomes around mid to late May. New plants germinate from seed that can lay dormant for several years beforehand. Habitat: Horse-nettle is found mainly in southwestern Ontario in cultivated fields, although herbarium records show that the species does grow in central and eastern Ontario. Competitiveness: Studies in field corn show little yield loss from the presence of horse-nettle, an indication that it is a poor competitor (Whaley and VanGessel, 2002; Prostko et al., 1994). Toxicity: Solanine, the poison found in horse-nettle, is at its highest levels in the fall. The consumption of berries presents the biggest risk of poisoning. Since the berries are the most palatable part of the plant they been attributed to illness and death of livestock and humans. Allowing the plant material and berries to dry down before feeding to livestock does not appear to reduce the risk of livestock poisoning. Fortunately, the sharp thorns on the stem deter many animals from consuming the plant. IDENTIFICATION CLUES Seedling Cotyledons: Oblong to elongated First leaves: The first leaves of horse nettle have alternate orientation. The first two leaves are sparsely hairy on the upper leaf surface and have entire margins. Mature leaves: The plant’s mature leaves have alternate leaf orientation. Its leaves are broadest in the middle and taper on both ends. They also have 2–5 rounded or sharply pointed lobes on each side. Both surfaces are covered with fine, star-shaped hairs and several long, hard spikes that run along the leaf veins Mature plant Stems: Horse-nettle’s stem is erect and branching near the top, and covered in tiny, star-shaped hairs and hard, sharp spines. It is green to purple in colour and grows up to 1 m in height. Flowers: Flowers grow in short clusters at the ends of branches. Each flower has five white or purple sepals that meet at a yellowish-orange centre made of joined stamens. The petals are 1.5–2 cm in diameter. Horse-nettle flowers from July until fall. Fruit: Immature fruit is dark green with light green stripes. Mature berries are smooth and yellow, and will wrinkle with age. Roots: Fibrous, attached to an extensive rhizome network Helpful tip Horse-nettle is distinguished by its spiny/thorny stems and leaves, its large white to purple flowers, its smooth yellow berries, and its rhizomes, which allow it to grow in thick patches. 160 WEED ID GUIDE FOR ONTARIO CROPS HORSE NETTLE 1 4 2 5 1 A pre-flowering plant during late June 2 The erect stem, branched and with several sharp spines 3 Leaves are deeply lobed with sharp spines, and flowers are a pale purple to white colour with five orange stamens forming a central column 4 Immature berries that start off green in colour 5 Mature yellow berries, each containing several seeds 3 WEED ID GUIDE FOR ONTARIO CROPS 161 EASTERN BLACK NIGHTSHADE* Nightshade or Potato (Solanaceae family) • Solanum ptychanthum Dunal EPPO Code: SOLPT Other names: black nightshade, deadly nightshade * POISONOUS WHEN CERTAIN PLANT PARTS ARE CONSUMED SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Range and habitat: Can be found throughout eastern Canada and is most commonly found on loam and clay loam soils although it exists in all soil types. Competitiveness: One of the less competitive weeds, however it negatively affects crop quality as the berries stain crop seed. Resistance: Populations of this weed exist that are resistant to Group 2 herbicides (e.g. imazethapyr). Toxicity: The mature berries have the highest concentration of solanine, a glycoalkaloid poison. In general, feeding experiments have shown that toxic affects occur when 25 percent or more of a cow’s forage intake is comprised of nightshade (Anonymous, 2015). IDENTIFICATION CLUES Leaves Cotyledons: Oblong or diamond shaped with hairy margins. Young leaves: Round to oval, the underside usually being purple and the leaf margins being entire to slightly toothed. Mature leaves: margins are wavy toothed, leaf shape is round to oval and underside is usually purple. Mature plant Stem: Erect, branched and mostly hairless; young stem is green but later turns purplish/green Flowers: Often 2–5 flowers grouped together; the petals are white and unite into a star shaped corolla with 5 sharp lobes; the anthers are united and form a yellow column in the center; flowers from June until late autumn. Fruit: Berries are green at first, but then turn black as they mature; when squeezed the berries will exude a purplish placenta containing several (~20–70) small flat seeds. OFTEN MISTAKEN FOR I know it’s NOT ... because… Pigweed species … Young eastern black nightshade plants have pointed, almost diamond shaped cotyledons compared to the linear cotyledons of pigweed species. The underside of eastern black nightshade leaves are typically a deep purple compared to the violet underside of pigweed species. The older leaves have wavy toothed margins whereas pigweed species lack the wavy toothed margins. Hairy nightshade … The leaf surface and stems of eastern black nightshade are hairless and the mature berries are black compared to the mature brown berries and hairy plant parts of hairy nightshade. 162 WEED ID GUIDE FOR ONTARIO CROPS EASTERN BLACK NIGHTSHADE 1 4 2 5 1 A 3-leaf seedling with oblong cotyledons 2 An 8–10 leaf plant with wavy toothed leaf margins 3 The purple underside of a mature leaf 4 A plant infesting soys with a mixture of immature green and mature black berries 5 Mature plant during late October in soybean with black berries 3 WEED ID GUIDE FOR ONTARIO CROPS 163 HAIRY NIGHTSHADE Nightshade or potato (Solanaceae family) • Solanum physalifolium Rusby EPPO Code: SOLSA Other names: potatoweed, cupped nightshade, brown berried nightshade SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Range and habitat: Hairy nightshade is most commonly found in sandy and muck soils. Competitiveness: Most nightshade species are not considered overly competitive, but the juicy berries can stain crop seed during the harvesting process. Toxicity: The concentration of glycoalkaloid toxins in hairy nightshade is thought to be low overall, but highest in immature berries. There is no evidence that ripe berries are toxic (Anonymous, 2015). IDENTIFICATION CLUES Leaves Cotyledons: Oblong with a pointed tip and hairy margins. Young leaves: Young leaves are round to oval in shape with hairy margins. Mature leaves: The apex is more pointed on older leaves than it is in younger ones. The leaf’s surface is finely hairy giving it a sticky feel. Its margins are hairy, but will occasionally have irregular rounded teeth. Mature plant Stem: The stem of hairy nightshade is extremely hairy. It is branched, and either erect or spreading. Flowers: The petals of its flowers are white and unite into a star-shaped corolla with five sharp lobes. The anthers are united and form a yellow column in the center. Hairy nightshade flowers from June until late autumn. Fruit: The plant produces berries that are green at first, but later turn brown as they mature. OFTEN MISTAKEN FOR I know it’s NOT … because … Pigweed species … Young hairy nightshade plants have elongated cotyledons. Pigweed species, on the other hand, have linear cotyledons. The surface and margins of hairy nightshade are extremely hairy, whereas most pigweed species lack dense leaf hairs. Eastern black nightshade … The leaf surface and stems of eastern black nightshade is hairless and the mature berries are black. Hairy nightshade, on the other hand, has mature, brown berries and very hairy leaves and stems. 164 WEED ID GUIDE FOR ONTARIO CROPS HAIRY NIGHTSHADE 1 4 2 5 1 A four leaf seedling with elongated, pointed cotyledons 2 A larger plant about to flower during mid-June 3 A flowering plant in late June 4 A mature leaf with pointed apex and hairy margin 5 The white star-shaped flower with yellow tubular floret 3 WEED ID GUIDE FOR ONTARIO CROPS 165 PALMER AMARANTH Pigweed (Amaranthaceae family) • Amaranthus palmeri Watson EPPO Code: AMAPA Other names: Palmer’s pigweed, carelessweed, dioecious amaranth SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed; dioecious (separate male and female plants). Emergence: In spring, typically after lamb’s quarters. Distribution and habitat: Palmer amaranth has not yet been found in Ontario or other provinces in Canada. A native of the southern USA, it has recently been moving north and has been found as close as Michigan. Adapted to dry and hot conditions in the southwest USA, it is now abundant in cultivated fields. Competitiveness: According to a summary by Legleiter and Johnson (2013), plants can grow as much as 5–8 cm/day and yield losses above 70 percent have been documented in both corn and soybeans. Resistance: In the United States populations exist that are resistant to Group 2 (e.g. imazethapyr), Group 3 (e.g. pendimethalin), Group 5 (e.g. atrazine), Group 9 (e.g. glyphosate), Group 14 (e.g. fomesafen) and Group 27 (e.g. mesotrione) herbicides. IDENTIFICATION CLUES Seedlings Cotyledons: Linear and narrow. First leaves: round ovate with an obtuse tip that ends in a notch. The petiole is longer that the leaf blade. Mature leaves: Palmer amaranth’s mature leave are ovate to diamond shaped (tapered with a pointed tip), often with a wavy margin. The petiole (leaf stalk) is typically thin and longer than the leaf blade. This is one method of distinguishing it from other pigweed species. Many, but not all plants may have a white to grey, V-shaped mark on the leaf blade. Mature plant Stem: Its stem has an alternate leaf orientation, is smooth with no hairs, and grows between 1.5–2.5m in height. Seed heads: Its seed heads have long, spikey clusters, similar to waterhemp, but with a terminal seed head much longer that can reach up to 90 cm long (Legleiter and Johnson, 2013). Only the female plants produce seed. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because… Redroot pigweed … The stem of redroot pigweed is covered in dense, short hairs, whereas Palmer amaranth’s stem is smooth and hairless. The petiole of Palmer amaranth is longer than the leaf blade whereas redroot pigweed’s is shorter. Green pigweed … the upper stem of green pigweed has a cluster of dense hairs, while the stem of Palmer amaranth is smooth and hairless. The petiole of Palmer amaranth is longer than the leaf blade whereas green pigweed’s is shorter. Waterhemp … the petiole of Palmer amaranth is longer than the leaf blade whereas waterhemp’s is shorter. 166 WEED ID GUIDE FOR ONTARIO CROPS PALMER AMARANTH 3 1 4 2 1 A seedling plant that looks like other pigweed species, but note the long petioles (leaf stalks) 2 Side view of the petiole that is often longer than that of the leaf blade 3 The more “diamond-shaped” leaves of Palmer amaranth prior to flowering 4 The long terminal seed head spike of Palmer amaranth WEED ID GUIDE FOR ONTARIO CROPS 167 GREEN PIGWEED Pigweed (Amaranthaceae family) • Amaranthus powellii S. Wats EPPO Code: AMAPO Other names: Powell amaranth SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Spring, typically after lamb’s-quarters. Habitat: Found in most cultivated fields. Less prevalent in winter cereals and established forage crops. Widespread across Ontario. Competitiveness: University of Guelph research examined competition in corn with pigweed at densities ranging from 16,000–32,000 plants/ac. When emerging at the 3–4 leaf stage of corn, yield losses have ranged from 22–52 percent. However when emergence was delayed until the 6–7 leaf stage, the impact on corn yield loss was reduced by 50 percent. Resistance: A number of populations are resistant to Group 2 (e.g. imazethapyr) and Group 5 (e.g. atrazine) herbicides in Ontario and throughout North America. IDENTIFICATION CLUES Seedlings Cotyledons: Linear, narrow. Purple–red underneath. Young leaves: Round to ovate with a short petiole, purple-red underneath, the upper surface is smooth and shiny. There is a small notch at the tip. Mature leaves: Ovate, shiny green and seemingly hairless. The tip of the leaf has a notch with a small spine (mucron). Mature plant Stem: Alternate leaf orientation; the upper stem will have a cluster of short hairs but otherwise the stem feels hairless. Dark pink to red, contrasting with the dark green leaves. Seed heads: Long finger like spikes that are coarse to the touch, but less so then the short compact spikes of redroot pigweed. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT . . . because . . . Waterhemp ... The upper stem of green pigweed will have a cluster of short hairs, whereas waterhemp’s stem is smooth and hairless. The tips of waterhemp leaves are not notched. Redroot pigweed ... The upper stem of green pigweed has a cluster of dense hairs whereas the stem of redroot pigweed is extremely hairy all over. The leaves of redroot pigweed are also a dull green compared to the more shiny leaves of green pigweed. Eastern black nightshade ... Young eastern black nightshade plants have pointed, almost diamond shaped cotyledons compared to the linear cotyledons of pigweed species. The underside of eastern black nightshade leaves are typically a deep purple compared to the violet underside of pigweed species. The older leaves have wavy toothed margins whereas pigweed species lack the wavy toothed margins. 168 WEED ID GUIDE FOR ONTARIO CROPS GREEN PIGWEED 1 4 2 5 1 A four-leaf seedling plant with ovate leaves, notched apex and narrow cotyledons 2 Three pigweed plants: the top two are redroot pigweed with larger pale green leaves; the bottom green pigweed with darker, shinier leaves. 3 The mature leaf tends to be shinier and darker green than other pigweeds. 4 Green pigweed’s stem is almost hairless with the majority of hairs on the top node. 5 The finger-like spikes of green pigweed tend to be longer than the short and compact ones of redroot pigweed. 3 WEED ID GUIDE FOR ONTARIO CROPS 169 REDROOT PIGWEED Pigweed (Amaranthaceae family) • Amaranthus retroflexus L. EPPO Code: AMARE Other names: pigweed, redroot, rough pigweed, tall pigweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Spring, typically after lamb’s-quarters. Habitat: Found in most cultivated fields. Less prevalent in winter cereals and established forage crops. Competitiveness: University of Guelph research examined competition in corn with pigweed at densities ranging from 16,000–32,000 plants/ac. When emerging at the 3–4 leaf stage of corn, yield losses range between 22–52 percent. However, when emergence was delayed until the 6–7 leaf stage, the impact on corn yield loss was reduced by 50 percent. Resistance: A number of populations are resistant to Group 2 (e.g. imazethapyr) and Group 5 (e.g. atrazine) herbicides in Ontario and throughout North America. IDENTIFICATION CLUES Seedlings Cotyledons: Linear, narrow, purple-red underneath. Mature leaves: Ovate, dull green and somewhat hairy, has a small notch with a spine (mucron) at the tip. Mature plant Stem: Alternate leaf orientation; the stem is coarse with many short hairs. Seed heads: Seed heads have short, thick spikes that are very coarse to the touch. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because… Waterhemp … the stem of redroot pigweed is covered in dense short hairs, whereas waterhemp is smooth and hairless. The tips of waterhemp leaves are not typically notched. Green pigweed … only the upper stem of green pigweed has a cluster of dense hairs whereas the stem of redroot pigweed is extremely hairy all over. The leaves of redroot pigweed are also a dull green compared to the more shiny leaves of green pigweed. Eastern black nightshade … young eastern black nightshade plants have pointed, almost diamond-shaped cotyledons compared to the linear cotyledons of pigweed species. The underside of eastern black nightshade leaves are typically a deep purple compared to the violet underside of pigweed species. The older leaves have wavy-toothed margins, whereas pigweed species lack the wavy-toothed margins. 170 WEED ID GUIDE FOR ONTARIO CROPS REDROOT PIGWEED 1 4 5 1 The linear/narrow cotyledons and ovate leaves of seedling plants 2 2 The dull green and wavy leaf margins of a 10 leaf seedling plant 3 Closeup of mature leaf 4 The short compact finger like spikes of the mature seed head. The finger-like spikes of green pigweed tend to be longer than the short and compact ones on redroot pigweed 5 The short but dense hairs that cover the stem of redroot pigweed 3 WEED ID GUIDE FOR ONTARIO CROPS 171 WATERHEMP Pigweed (Amaranthaceae family) • Amaranthus tuberculatus (Moq.) Sauer var. rudis (Sauer) Costea & Tardif EPPO Code: AMARU Other names: common waterhemp SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed, dioecious, has separate male and female plants. Emergence: Spring, typically after lamb’s-quarters. Habitat: Not native to Canada. Now found throughout Ontario, mainly along waterways and beaches. Prefers full or partial sun, moist or wet conditions. Competitiveness: In University of Guelph research trials, poor control of waterhemp has resulted in over 85 percent yield loss in both corn and soybeans. Resistance: A number of populations are resistant to Group 2 (e.g. imazethapyr), Group 9 (e.g. glyphosate) and Group 5 (e.g. atrazine) herbicides in Ontario and throughout North America. IDENTIFICATION CLUES Seedlings Cotyledons: Linear, narrow, purple-red underneath. Mature leaves: Lance-shaped (tapered and typically with a pointed tip), with a wavy margin. Mature Plant Stem: Alternate leaf orientation; smooth with no hairs; variable colouring (green to red/ purple); 1.5–2.5 m in height. Seed heads: Long, spikey clusters (somewhat similar to ragweed) that can vary in colour from green to red to purple. Only the female plants produce seed. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because… Redroot pigweed … The stem of redroot pigweed is covered in dense short hairs, whereas waterhemp is smooth and hairless. The tips of waterhemp leaves are typically not notched. Green pigweed … The upper stem of green pigweed has a cluster of dense hairs whereas the stem of waterhemp is smooth and hairless. Waterhemp will typically have narrower leaves with wavy margins and without a notched tip. Eastern black nightshade … The leaf margins of young eastern black nightshade leaves are hairy and the older leaves have wavy toothed margins whereas waterhemp leaves are hairless with wavy margins. 172 WEED ID GUIDE FOR ONTARIO CROPS WATERHEMP 4 1 5 2 1 A ten-leaf hairless seedling plant with narrower, wavy margined leaves compared to other pigweed species 2 A close-up of a mature and narrow waterhemp leaf 3 The completely hairless and smooth stem of waterhemp 4 The very long, fingerlike spikes of the female seed head 5 Male (left) and female (right) plants with reddish-purple flowers in a Kent county soybean field 3 WEED ID GUIDE FOR ONTARIO CROPS 173 MOUSE-EARED CHICKWEED Pink (Caryophyllaceae family) • Cerastium fontanum Baumg. EPPO Code: CERVU Other Names: mouse ear chickweed, large mouse ear chickweed, mouse-ear SPECIES INFORMATION Lifecycle: Annual, but more commonly perennial. Propagation: Mouse-eared chickweed reproduces by seed and by horizontal stems that root at the nodes forming dense patches. Emergence: Seed will germinate throughout the season; established plants will remain dormant over the winter, but will resume growth at relatively cool temperatures. Habitat: Mouse-eared chickweed is found throughout Ontario in a wide range of habitats, including in cultivated fields, but is most common in turf. IDENTIFICATION CLUES Seedling Cotyledons: They are small oval and shiny green with a very short petiole. First leaves: They are oval, dark green in colour and have hairy entire margins and a pointed tip. They grow in opposite orientation. The petioles are hairy. Mature leaves: The mature leaves of mouse-eared chickweed are similar to its younger leaves. Mature plant Stem: Its stem is prostrate and densely hairy with swollen nodes that root into the soil when they come into contact. Flowers: Mouse-eared chickweed has very small flowers with five white two-lobed petals, which gives it the appearance of having 10 petals. Fruit: The fruit of mouse-eared chickweed is contained in an oval capsule. It is reddishbrown to rusty in colour and triangular to angular shaped. Roots: Fibrous roots, because of its prostrate habit, it can form new roots at the nodes. Note of interest Mouse-eared chickweed has very hairy, round to ovate leaves shaped like mouse ears, hence the name. OFTEN MISTAKEN FOR I know it’s NOT … because … Grass-leaved stitchwort … Grass-leaved stitchwort is hairless compared to the densely hairy mouse-eared chickweed. Common chickweed …mouse-eared chickweed is dark green and has densely hairy leaves and stems while chickweed is pale green and is almost hairless except for a sinle line of hair on one side of the stem. 174 WEED ID GUIDE FOR ONTARIO CROPS MOUSE-EARED CHICKWEED 1 3 2 1 A seedling plant 2 Vegetative growth emerging from over-wintered root stock in winter wheat 4 3 A rosette in early May that had over-wintered 4 Opposite leaf orientation on a hairy stem 5 A flower consisting of five white and deeply lobed petals 5 WEED ID GUIDE FOR ONTARIO CROPS 175 WHITE COCKLE Pink (Caryophyllaceae family) • Silene latifolia Poir. EPPO Code: MELAL Other Names: white campion SPECIES INFORMATION Lifecycle: Biennial or short-lived perennial. Propagation: Reproduces by seed. Emergence: White cockle emerges predominately in the spring, but can emerge in the fall. Habitat: It is commonly found in pastures, on roadsides, in waste areas and occasionally in cultivated fields throughout southeastern Ontario. Typically, the plant is found in forage crops and on heavier soils, but increasingly it’s presenting a problem in minimum-till corn and soybean fields. Competitiveness: White cockle is very competitive, as it grows quickly in the spring and flowers and sets seed throughout the summer. Although it can affect stand establishment in forages, it has very little impact on forage quality. IDENTIFICATION CLUES Seedling Cotyledons: Lanceolate or ovate with a pointed tip, gradually tapering into a stalk. First leaves: The plant’s first few leaves appear as a rosette, they are lanceolate to ovate, tapering into a stalk. They are pale yellow to green in colour and have fine hairs along the perimeter. Mature leaves: White cockle’s mature leaves are soft and hairy on both sides. The margins of leaves are entire, hairy and somewhat wavy. Middle and upper leaves are stalk-less, have no teeth, and are hairy, long and lance-shaped, tapering to a point. Mature plant Stem: The stems of mature plants have opposite leaf orientation. The stem is erect and grows up to 1.2 m high. It is round and swollen at the nodes, and hairy but not sticky. Flowers: The male calyx has 10 distinctive purplish lengthwise veins. The female (seed producing) calyx has five prominent veins and usually three much fainter veins in between. The plant’s flowers have five white, large and showy petals that are deeply lobed. Seeds: Seeds are kidney shaped, rough in texture and grayish-orange in colour. White cockle’s seed pods have 10 teeth. Roots: Fleshy taproot. OFTEN MISTAKEN FOR I know it’s NOT … because … Purple cockle … purple cockle has narrow leaves, silky hairs on its stem and large purple flowers, while white cockle has broader leaves and white to pink flowers with short calyx lobes. Bladder campion … the calyx of bladder campion is “papery”, bladder-shapped, and smooth. White cockle, on the other hand, has a distinctively hairy calyx. Night-flowering catchfly… night-flowering catchfly is very sticky to the touch, especially the stem and calyx, while white cockle is not sticky at all. 176 WEED ID GUIDE FOR ONTARIO CROPS WHITE COCKLE 1 4 2 5 1 Seedling rosette with opposite leaves 2 A large, well-established plant that is about 50–60 cm tall 3 Mature, elongated and hairy leaves with entire margins, pointed tips and prominent veins 4 Side view of a flower showing the calyx with prominent veins 5 Front view of the flower with its five, deeply-lobed petals 3 WEED ID GUIDE FOR ONTARIO CROPS 177 NIGHT-FLOWERING CATCHFLY Pink (Caryophyllaceae family) • Silene noctiflora L. EPPO Code: MELNO Other Names: sticky cockle SPECIES INFORMATION Lifecycle: Annual, winter annual. Propagation: Reproduces by seed. Emergence: Night-flowering catchfly will germinate when soil temperatures are as low as 6˚ C and as high as 31˚ C (McNeill, 1980). Habitat: The plant is commonly found in pastures, waste areas and cultivated fields, as well as along roadsides. Competitiveness: A Swedish study found that Night-flowering catchfly had a relatively small influence on the yield of spring cereals and was considered benign (Boström et al., 2003). IDENTIFICATION CLUES Seedling Cotyledons: Oblong or club-shaped, tapering into a short stalk. Young leaves: Night-flowering catchfly’s first leaves are opposite, ovate and hairy. Young plants produce a rosette. Mature leaves: The plant’s mature leaves are opposite, ntire with smooth margins, tapering towards both ends, and have prominent veins. The leaves are densely hairy and sticky to the touch. Mature plant Stem: The stem of night-flowering catchfly is erect and branchy with dense hair. The stem is sticky to touch. Flowers: The calyx is densely hairy and sticky with five prominent veins and five white, lobed petals. Seeds: Night-flowering catchfly’s seeds are kidney shaped and grayish-orange. Roots: Taproot with fine branches OFTEN MISTAKEN FOR I know it’s NOT … because … Bladder campion and white cockle … Night-flowering catchfly is very sticky to touch, especially the stem and calyx, while bladder campion and white cockle are not sticky at all. 178 WEED ID GUIDE FOR ONTARIO CROPS NIGHT-FLOWERING CATCHFLY 1 3 2 1 A mature flowering plant 2 Leaves tapering towards both ends, prominent veins, densely hairy and sticky to the touch 4 3 Five deeply lobed and white petals of night-flowering catchfly 4 The densely hairy and sticky calyx with prominent veins WEED ID GUIDE FOR ONTARIO CROPS 179 BLADDER CAMPION Pink (Caryophyllaceae family) • Silene vulgaris (Moench) Garcke EPPO Code: SILVU Other Names: cow bell, rattleweed SPECIES INFORMATION Lifecycle: Perennial Propagation: Bladder campion reproduces by seed and by underground branches that originate from the crown. Emergence: New shoots will arise in the spring Habitat: Bladder campion is commonly found in pastures, along roadsides and in waste areas. Occasionally, it is found in cultivated fields throughout southeastern Ontario. Typically, it is found in forage crops, but increasingly it is a problem in minimum-till corn and soybean fields. IDENTIFICATION CLUES Seedling Cotyledons: Fleshy, oblong to elongated. Young leaves: Bladder campion’s first leaves are opposite, ovate, dull green and hairless. Young plants produce a rosette. Mature leaves: The mature leaves of bladder campion are opposite, narrowly oval and taper to a point. They are hairless and have entire margins. The leaves can sometimes feel waxy. Mature plant Stem: The plant’s stem is much branched, round and hairless. Flowers: Five, deeply-lobed white petals grow at the end of a bladder-like calyx. Bladder campion flowers from June to September. Seeds: Its seeds are kidney shaped, rough in texture and grayish in colour. Roots: Bladder campion has a taproot with several wiry and whitish branches that form new shoots. OFTEN MISTAKEN FOR I know it’s NOT … because … Purple cockle … Purple cockle has silky hairs on its stem and large purple flowers, while bladder campion is smooth, hairless and has white petals on a bladder-like calyx. White cockle … Bladder campion is “papery”, smooth and hairless, and its calyx smooth and bladder-shaped. The calyx of white cockle is distinctively hairy. Night-flowering catchfly … Night-flowering catchfly is very sticky to touch, especially on its stem and calyx. Bladder campion, on the other hand, is not sticky at all. 180 WEED ID GUIDE FOR ONTARIO CROPS BLADDER CAMPION 1 3 2 4 1 An established perennial plant that has emerged in mid-May 2 The yellowish taproot with several wiry, white branches 3 The opposite narrowly oval leaves that taper at the base and are attached directly to the stem 4 A flowering plant in a corn field during mid-June 5 A close-up of the five, deeply-lobed petals on a bladder-like calyx 5 WEED ID GUIDE FOR ONTARIO CROPS 181 CORN SPURRY Pink (Caryophyllaceae family) • Spergula arvensis L. EPPO Code: SPRAR Other names: spurrey SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Typically, corn spurry germinates and emerges in the early part of spring. Habitat: While it is found throughout Ontario, corn spurry is most commonly found on light sandy soils. Competitiveness: A Canadian study conducted in spring cereals demonstrated that corn spurry was not a very competitive species. A density of over 250 plants/m2 was required before an economic threshold was reached (Weaver and Ivany, 1998). However, a Swedish study found that corn spurry was detrimental in spring cereals compared to other species. However, yield loss calculated from 1,691 trials was only 5.4 percent (Milberg and Hallgren, 2004), so even if detrimental, the impact on yield loss would be relatively small. IDENTIFICATION CLUES Seedling Cotyledons: Filiform and cylindrical, similar to true leaves. Young leaves: The first leaves of corn spurry are long and narrow, and grow in a rosette-like cluster. Mature leaves: Mature leaves are similar in size and shape to first leaves, but they grow in whorls of 6–30 at each node. Mature plant Stem: Its stem is much branched, finely hairy and sometimes sticky. It is bright green in colour and grows 10–50 cm tall. Flowers: Corn spurry has very small flowers with five white petals offset by five green sepals that are clustered on short stalks at the top of the plant. Fruit: The plant’s seedpods are round and split into five divisions that are filled with many flat, black and round seeds. Roots: Taproot with fibrous lateral roots. OFTEN MISTAKEN FOR I know it’s NOT … because … With its many, very narrow leaves that form a whorl at each node, corn spurry rarely gets confused with other weed species that have whorled leaves, such as carpetweed, cleavers and smooth bedstraw. 182 WEED ID GUIDE FOR ONTARIO CROPS CORN SPURRY 1 3 4 1 A small seedling with long narrow cotyledons and first leaves 2 2 An older plant with several long narrow leaves that form a whorl at each stem node 3 A mature flowering plant 4 Small flowers with five white petals and five green sepals WEED ID GUIDE FOR ONTARIO CROPS 183 CHICKWEED Pink (Caryophyllaceae family) • Stellaria media (L.) Vill. EPPO Code: STEME Other Names: common chickweed SPECIES INFORMATION Lifecycle: Annual or winter annual Propagation: Reproduces by seed. Emergence: Typically two main flushes of germination in the spring and in the autumn. Habitat: Chickweed is found throughout Ontario in a wide range of habitats and in many cultivated crops. Competitiveness: Since chickweed typically occurs at high plant densities its impact on yield can be quite significant. It is also an alternate host for other crop pests, namely wireworm and soybean cyst nematode. IDENTIFICATION CLUES Seedling Cotyledons: Oblong to elongated with pointed apex. First leaves: Chickweeds first leaves are oval, and have opposite orientation, entire margins and a pointed tip. Leaf stalks are hairy. Mature leaves: Similar to its younger leaves. Mature plant Stem: Prostrate, spreading or sometimes erect, depending on the environment, chickweed’s stem has a narrow, lengthwise strip of fine hairs that alternate side after each node. Flowers: Chickweed has very small flowers with five white, two-lobed petals that give it the appearance of 10 petals. Fruit: The fruit of chickweed appears as an oval capsule that contains several light brown to reddish seeds, which are flat and circular with a notch. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Grass-leaved stitchwort … the stem of grass-leaved stitchwort lacks the lengthwise fine hairs of chickweed. In comparison to chickweed, which has sparse hairs, grass-leaved stitchwort is hairless. Scarlet pimpernel … the leaves of scarlet pimpernel have several small purple spots, while chickweed leaves lack any markings at all. While chickweed flowers are white flowers, the flowers of scarlet pimpernel are salmon-coloured. Mouse-eared chickweed … chickweed is hairless except for a single line of hairs along the stem while mouse-eared chickweed is hairy all over. 184 WEED ID GUIDE FOR ONTARIO CROPS CHICKWEED 1 3 2 1 A small seedling with opposite leaves 2 Rosette-looking, mature, flowering plant in mid-June 4 3 The stems contain a line of short hairs that alternate from one side to another following each internodes 4 A flower consisting of five white and deeply lobed petals 5 Flowering chickweed in a winter wheat field during early May 5 WEED ID GUIDE FOR ONTARIO CROPS 185 NARROW-LEAVED PLANTAIN Plantain (Plantaginaceae family) • Plantago lanceolata L. EPPO Code: PLALA Other Names: buckhorn plantain, English plantain, ribgrass SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed Emergence: Most seedlings emerge in spring or early fall. Habitat: Narrow-leaved plantain is commonly found throughout Ontario in cultivated fields, pastures, lawns and gardens, and along roadsides. Competitiveness: Typically, narrow-leaved plantain is found in older pastures and hay fields where it is more a symptom of declining forage stands. The forage quality of narrowleaved plantain is adequate, but pollen can cause hay fever. IDENTIFICATION CLUES Seedling Cotyledons: Linear and very long. First leaves: Narrow-leaved plantain’s first leaves are hairy along the margins and elongated with prominent whitish parallel veins. Mature leaves: Mature leaves form in a basal rosette. They are elongated with 3–5 prominent whitish veins. Although the plant’s leaves appear smooth they have silky hairs on the leaf surface, usually near the base. Mature plant Stems: Narrow-leaved plantain has no stem; its leaves come from a basal rosette. Flowers: Its flowers are contained in a dense cylindrical-shaped seed head at the end of a long ridged stalk that arises from the basal rosette. Seeds: Seeds are 1.5–3.5 mm long, brown and shiny, and have an indentation on one side that becomes sticky when wet, which aids in the dispersal by animals. Roots: Short taproot with fibrous roots. OFTEN MISTAKEN FOR I know it’s NOT … because … Broad-leaved plantain … The thick, oval leaves of broad-leaved plantain differ from the long and narrow leaves of narrow-leaved plantain. 186 WEED ID GUIDE FOR ONTARIO CROPS NARROW-LEAVED PLANTAIN 1 4 2 5 1 A seedling with its linear cotyledon and long, narrow young leaves 2 An older rosette made of elongated leaves with the 3–5 prominent veins 3 A close-up of the leaves with their whitish prominent veins 4 A mature flowering plant 5 A mature seed head 3 WEED ID GUIDE FOR ONTARIO CROPS 187 BROAD-LEAVED PLANTAIN Plantain (Plantaginaceae family) • Plantago major L. EPPO Code: PLAMA Other Names: plantain, common plantain, doorweed, dooryard plantain SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed. Emergence: Broad-leaved plantain intermittently germinates from late April to late September with peak flushes in May. Habitat: The plant is most commonly found in southwestern Ontario in row crops (mainly in minimum tilled cropping systems), waste places and open fields. It establishes in all types of soil. Competitiveness: Little data exists on this species competitiveness, but established populations will negatively affect crop establishment. IDENTIFICATION CLUES Seedling Cotyledons: Oblong with a rounded point. First leaves: The plant’s first leaves are oblong to oval with an entire margin. Mature leaves: Mature leaves form a rosette. All leaves have an elastic leafstalk; when pulled it will separate from the leaf, but the veins will remain intact. Mature plant Stems: Broad-leaved plantain has no stem; the leaves come from a basal rosette. Flowers: Broad-leaved plantain has small, white flowers (1 mm) that grow on long leafless stalks that emerge from the rosette. Broad and ovate bracts surround the flowers, and seeds are produced in an oval, two-celled capsule. Seeds: The seeds of broad-leaved plantain are light to dark brown and glossy. They grow to 1–1.5 mm in length. Roots: Short taproot with fibrous roots. OFTEN MISTAKEN FOR I know it’s NOT … because … White cockle … broad-leaved plantain is more or less hairless compared to the extremely hairy white cockle. Narrow-leaved plantain … the oval leaves of broad-leaved plantaing distinguish it from narrow-leaved plantain which has narrow elongated leaves. 188 WEED ID GUIDE FOR ONTARIO CROPS BROAD-LEAVED PLANTAIN 1 3 2 1 Seedling with its oblong cotyledon and long oval first leaf 2 New growth of an established perennial plant in early spring after overwintering 4 3 An older rosette with oval leaves that have wavy margins 4 Leaf veins are prominent and easily exposed when the leaf is torn from the base 5 A mature plant with its tall flowering stalks 5 WEED ID GUIDE FOR ONTARIO CROPS 189 POKEWEED* Pokeweed (Phytolaccaceae family) • Phytolacca americana L. EPPO Code: PHTAM Other Names: inkweed, pokeberry * POISONOUS TO LIVESTOCK WHEN CONSUMED SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed Emergence: Germination and emergence have been observed throughout the spring, summer and fall, with fall seemingly the most common time for emergence in cultivated fields. Habitat: Native to Canada, pokeweed is found in meadows, at the edge of woodlots, and in fencerows and waste areas in Southern Ontario. Competitiveness: The juice inside pokeweed berries will stain crop seeds and reduce its quality and value. Toxicity: The plant is very poisonous to livestock. If consumed, pokeweed may cause vomiting, paralysis and even death. IDENTIFICATION CLUES Seedling First leaves: The leaves and stem of pokeweed are fleshy and smooth in appearance. Mature leaves: With an alternate leaf orientation, the lower leaves are wide, large and long, while the upper leaves are dark green and small with shorter leafstalks and pink-green veins. Mature plant Stem: Erect, long (up to 3m), smooth, hairless, “juicy-looking” and pink to bright red in colour. Flowers: The plant’s flowers have no petals, but five petal-like sepals that are green, white to pinkish in slender racemes or clusters at the ends of main stems and branches. Fruit: Pokeweed produces purplish berries that exude a crimson juice. Roots: Perennial taproot Identification tip: Pokeweed plants are distinguished by a soft, fleshy appearance and the flat, juicy, purple berries in a spike at the ends of smooth stems. 190 WEED ID GUIDE FOR ONTARIO CROPS POKEWEED 1 3 2 4 1 Young plant in mid-July that has emerged from a perennial taproot 2 The smooth and hairless reddish purple stem 3 A 1.5 m tall flowering plant during mid-July 4 A close up of the flower prior to the formation of berries 5 The seed head consisting of several berries, which range from immature (green) to mature (purple) 5 WEED ID GUIDE FOR ONTARIO CROPS 191 SCARLET PIMPERNEL* Primsose (Primulaceae family) • Anagallis arvensis L. EPPO Code: ANGAR Other Names: red chickweed, poison chickweed, eye-bright, shepherd’s clock * POISONOUS TO LIVESTOCK WHEN CONSUMED SPECIES INFORMATION Lifecycle: Annual or winter annual. Propagation: Reproduces by seed. Emergence: Will germinate throughout the growing season. Habitat: Scarlet pimpernel is found throughout Ontario, but most commonly in turf, along roadsides and in waste areas. Historically, it is not found in cultivated fields but more recently it has been found in those habitats. Competitiveness: No data exits, but likely similar to chickweed. Toxicity: Poisoning and sometimes death have been reported in numerous animals after they have consumed large quantities of vegetation or seed (Mulligan and Munroe, 1990). Thankfully, it is rare that the species dominates a landscape so much so that animals consume the plant in large quantities. IDENTIFICATION CLUES Seedling Cotyledons: smooth and triangular to diamond shaped with short stalk. Young leaves: Its first leaves are oval with opposite orientation and entire margins. The shape varies from triangular to round with a pointed to round apex. Leaves look very similar to common chickweed. Mature leaves: Mature leaves look similar to the younger leaves but with several dark brown to purplish to black spots on the underside. Mature plant Stem: Scarlet pimpernel’s stem is four-angled or squared, hairless and branched at the base. Flowers: they are small with five salmon-coloured petals. The flower’s stamens have yellow anthers on purplish filaments. Fruit: The fruit of scarlet pimpernel is a rounded, one-cell capsule with seeds that are dull brown to black, 1–1.5 mm long and three-angled. Roots: Shallow, fibrous taproot. OFTEN MISTAKEN FOR I know it’s NOT … because … Chickweed … the leaves of scarlet pimpernel have several small dark spots while chickweed leaves lack any markings at all. The stem of scarlet pimpernel is hairless while that of chickweed bears a single row of hairs alternating sides at each internode. The flowers of scarlet pimpernel are salmon coloured, while chickweed has white flowers. 192 WEED ID GUIDE FOR ONTARIO CROPS SCARLET PIMPERNEL 1 3 4 1 A patch of flowering scarlet pimpernel in late June 2 2 The distinct dark spots on the leaf underside 3 The four-angled or squared stem 4 A flower with the five salmoncoloured petals and stamens with yellow anthers on the end of purple filaments WEED ID GUIDE FOR ONTARIO CROPS 193 PURSLANE Purslane (Portulacaceae family) • Portulaca oleracea L. EPPO Code: POROL Other Names: portulaca, pursley, pusly, pussley, wild portulaca SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Purslane is considered a late-germinating species in the spring since the seeds require high soil temperatures with poor germination under 24˚C (Miyanishi and Cavers, 1980). Habitat: Purslane is almost never found in grain crops and is much more common in horticultural crops and home gardens. Competitiveness: Purslane is not an overly competitive plant because it germinates late in the season and has a prostrate growth habit. It is a succulent and an edible plant. IDENTIFICATION CLUES Seedling Cotyledons: Elongated to oblong, club-shaped and succulent. Young leaves: Purslane’s first leaves are opposite or nearly opposite, club-shaped, fleshy and sometimes have reddish margins. Mature leaves: The species’ older leaves appear very similar to its young leaves. Mature plant Stems: Purslane’s stem is branched, succulent, prostrate and deep red in colour. Flowers: Purslane has small, five-petal, yellow and lobed flowers. Seeds: Its seeds are flat, round to kidney shaped, and housed in a bowl-shaped seedpod. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Spotted spurge … purslane lacks the oval red “spot” in the middle of each leaflet nor will it exude the milky juice that spotted spurge does when its leaves are removed from the stem. 194 WEED ID GUIDE FOR ONTARIO CROPS PURSLANE 1 2 4 1 A seedling with elongated cotyledons and club-shaped leaves 3 2 Opposite leaf orientation 3 The red fleshy stems with seedpods above the stem node 4 The prostrate nature of purslane WEED ID GUIDE FOR ONTARIO CROPS 195 SULPHUR CINQUEFOIL Rose (Rosaceae family) • Potentilla recta L. EPPO Code: PTLRC Other Names: yellow cinquefoil, cinquefoil SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed. Emergence: Sulphur cinquefoil seed prefers warm and sunny environments for maximum germination (Werner and Soule, 1976). Habitat: Sulphur cinquefoil is found most commonly in waste areas and pastures, and along roadsides. Occasionally, it can be found in no-till crop production systems. Competitiveness: No data exits on the competitiveness of sulphur cinquefoil, but it is not considered a significant weed in agricultural crops. In fact, it is more often considered an ornamental plant. IDENTIFICATION CLUES Seedling Cotyledons: Orbicular Young leaves: The first leaves of sulphur cinquefoil are round to oval and have deeply toothed margins. Mature leaves: Its mature leaves are palmately compound and made up of five to seven narrow, deeply toothed, hairy leaflets borne on a long hairy petiole (stalk). Mature plant Stem: Sulphur cinquefoil’s stem is hairy, grows 20–80 cm tall and branched at the base. Flowers: Flowers have five, light yellow petals that are 2–2.5 cm across. Fruit: Sulphur cinquefoil’s fruit is 1–1.5 mm long and wrinkly-ridged. Roots: Coarse fibrous root system. OFTEN MISTAKEN FOR I know it’s NOT … because … Rough cinquefoil … Sulphur cinquefoil has compound leaves with 5–7 leaflets while rough cinquefoil’s compound leaf has three leaflets. Marijuana … rough cinquefoil is a much shorter plant. Marijuana has compound leaves that are much larger; each plant has more leaflets than rough cinquefoil. 196 WEED ID GUIDE FOR ONTARIO CROPS SULPHUR CINQUEFOIL 2 1 1 A compound leaf with seven narrow, deeply toothed leaflets at the end of a hairy petiole 2 A young plant, much branched at the base, with numerous compound leaves with 5–7 narrow, deeply toothed leaflets 3 A light yellow, five-petaled flower 3 WEED ID GUIDE FOR ONTARIO CROPS 197 PROSTRATE KNOTWEED Smartweed (Polygonaceae family) • Polygonum aviculare L. EPPO Code: POLAV Other Names: doorweed, knot-grass, mat-grass, road-spread SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: One of the first annual broadleaf weed species to germinate and emerge in the spring. Habitat: Prostrate knotweed is mainly found on heavily compacted soils, and most commonly in turf and in the cracks of pavement, sidewalks or landscape stone. It can also be found in cultivated fields, but when it does, the plant appears more upright and succulent, and has broader leaves. Competitiveness: Little data exists on this species competitiveness. A Swedish study that evaluated weed competition in wheat stated that prostrate knotweed “seemed to be the most benign weed species,” while an Italian study identified yield losses in chickpea ranging from a low of 14 percent (at 16,000 plants/ac) to a high of 88 percent (at 130,000 plants/ac. IDENTIFICATION CLUES Seedling Cotyledons: Linear First leaves: Prostrate knotweed’s first leaves are alternate, elongated and surrounded by a membranous sheath called an ocrea at the base of the leaf where it meets the stem. Mature leaves: Mature leaves appear very similar to the young leaves, but they are larger. Mature plant Stems: The stem of prostate knotweed is wiry, slender, branched and prostrate in compacted landscapes or with full sunlight, but usually upright when in partially-shaded areas like field crops. Flowers: Prostrate knotweed’s flowers are small and inconspicuous with five small and greenish to pinkish sepals that appear in clusters at the leaf axils, and are partially enclosed in the ocrea. Seeds: Dull brown, triangular and about 2 cm long. Roots: Taproot that penetrates deeply in the soil and make the plant difficult to pull out. OFTEN MISTAKEN FOR I know it’s NOT … because … Striate knotweed … prostate knotweed has much smaller and narrower leaves and is much less upright, regardless of environment. 198 WEED ID GUIDE FOR ONTARIO CROPS PROSTRATE KNOTWEED 1 3 2 4 1 Seedling with linear cotyledons 2 A young plant in corn during midJune 3 A mature plant in mid-September 4 A close up of the membranous sheath called an ocrea that wraps around each node 5 A close up of the flower with its five small, greenish to pinkish sepals 5 WEED ID GUIDE FOR ONTARIO CROPS 199 WILD BUCKWHEAT Smartweed (Polygonaceae family) • Fallopia convolvulus (L.) Á. Löve EPPO Code: POLCO Other Names: black bindweed, climbing bindweed, corn bindweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces only by seed. Emergence: One of the first annual broadleaf weeds to germinate and emerge in the spring. Habitat: Wild buckwheat is commonly found in cultivated fields throughout Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that wild buckwheat densities of 20,000 plants/ac can result in 10–15 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Seedling Cotyledons: Elongated with a rounded apex and attached directly to the stem. First leaves: Wild buckwheat’s first leaf is shaped like an arrowhead or spade with pointed basal lobes. Mature leaves: The mature leaves of wild buckwheat have an alternate leaf orientation. They are similar to younger leaves, but larger and with more prominent veins. Mature plant Stems: The stems of wild buckwheat are long and slender. Spreading and vine-like, they wrap around other plants and objects. The stems have a membranous sheath, an ocrea, which surrounds each node. Flowers: Flowers consist of five small and greenish to white-pink sepals that are located at the tips of short branches or from leaf axils. Seeds: Dull black, 3mm long and shaped like a CFL football. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Field and hedge bindweed … wild buckwheat has an ocrea that surrounds the leaf stem at each node and lacks the round, showy morning glory-like flowers of bindweed species. 200 WEED ID GUIDE FOR ONTARIO CROPS WILD BUCKWHEAT 4 1 5 1 Seedling with elongated cotyledons 2 2 A young plant with its arrowheadshaped leaf 3 A young plant in a cornfield during early June 4 A close up of the flower with its five small and greenish to pinkish sepals 5 Mature flowering plant in early July that has escaped herbicide applications in corn 3 WEED ID GUIDE FOR ONTARIO CROPS 201 LADY’S THUMB Smartweed (Polygonaceae family) • Persicaria maculosa Gray EPPO Code: POLPE Other Names: red shank, smartweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Germinates and emerges early in the spring. Habitat: Lady’s thumb can be found throughout Ontario, although it is most often found in cultivated crops, waste places and open fields. The plant establishes in all types of soil. Competitiveness: Agriculture and Agri-Food Canada research has shown that lady’s thumb densities of 20,000 plants/ac can result in 13–15 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Seedling Cotyledons: Oblong tapering into a short stalk, sometimes reddish purple underneath. First leaves: Lady’s thumb has elongated, alternate first leaves, often with black dots on the upper surface. Sometimes it has a black, triangular imprint, referred to as the “thumb mark,” which gives the plant its common name. Mature leaves: Appear similar to younger leaves with alternate leaf orientation. Leaves are elongated and have wavy margins, as well as the black “thumb mark.” Mature plant Stems: The stems of lady’s thumb are erect and smooth, and range in colour from red to reddish-green to green. The membranous sheath surrounding the stem at each node, called the ocrea, is hairy. Flowers: Lady’s thumb flowers are small, each with five pinkish-white to pink sepals. The flowers are dense and crowded into narrow, cylindrical spikes. Seeds: The plant’s seeds are smooth, shiny black, typically flat, and oval with a pointed tip. Individual seeds are about 2 mm in diameter. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Pale/green smartweed … the ocrea of lady’s thumb is covered in short hairs and has a fringe of hairs on the top margin whereas the ocrea of pale/green smartweed is hairless. 202 WEED ID GUIDE FOR ONTARIO CROPS LADY’S THUMB 3 1 2 1 A seedling plant in early June 2 A young plant with its elongated leaves containing the dark triangular “thumb-print” 4 3 The ocrea, a membranous sheath that encircles the stem at each node 4 Pinkish-white flowers are densely crowded into narrow spikes WEED ID GUIDE FOR ONTARIO CROPS 203 DOCKS (CURLED AND BROAD-LEAVED DOCK) Smartweed (Polygonaceae family) • Rumex crispus L. and Rumex obtusifolius L. EPPO Code: RUMCR, RUMOB Other Names: curly dock, blunt-leaved dock SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed. Emergence: Docks germinate mainly in early spring and autumn with a higher percentage of seed germinating when on the soil’s surface rather than when buried (Pye and Andersson, 2009). Habitat: Docks can be found throughout Ontario. They are most often found in moist waste places, along fencerows and roadsides, and in pastures. They are occasionally found in cultivated fields. Competitiveness: No data exists on the competitiveness of docks. IDENTIFICATION CLUES Seedling Cotyledon leaves: Elongated Leaves (curled dock): The leaves of curled dock are long (10–30 cm) and narrow with very wavy margins. They are green with reddish purple blotches. Leaves (broad-leaved dock): Broad-leaved dock leaves are much wider than those of curled dock; the base is heart-shaped. They have wavy margins and the surface is green with reddish-purple blotches. Mature plant Stems: Both species have a membranous sheath, called an ocrea, which wraps around where the leaf stem attaches to the main stem. Leaves are alternate. Flowers: Both species have small, green flowers clustered in whorls around the branches of the main inflorescence. Fruit: Docks produce brown fruit with three wing-like papery sections that contain one prominent, egg-shaped seed. Broad-leaved dock fruit differs in that the wing-like papery sections have irregularly toothed margins whereas curled dock has entire margins. Roots: Strong and deeply penetrating taproot. 204 WEED ID GUIDE FOR ONTARIO CROPS DOCKS 1 3 2 1 The elongated cotyledons and round first leaves 2 The long narrow leaves of curled dock with very wavy margins 4 3 The comparatively wide leaves of broad-leaved dock 4 The membraneous sheath (called an ocrea) surrounds the stem of both docks at each node 5 Fruit of curled-dock with its three-winged papery sections with entire margins and large seed in the middle. In comparison, broadleaved dock would have fruit with irregularly toothed margins. 5 WEED ID GUIDE FOR ONTARIO CROPS 205 THREE-SEEDED MERCURY Spurge (Euphorbiaceae family) • Acalypha rhomboidea Raf. EPPO Code: ACCRH Other Names: copperleaf, rhombic copperleaf SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Three-seeded mercury is not considered an early germinating species. Typically, it emerges in late spring. Habitat: Most common in south-central Ontario, three-seeded mercury is most often found around field boundaries, near open woods. It can, however, be found in cultivated crops, ditches, and road sides. IDENTIFICATION CLUES Seedlings Cotyledons: Orbicular, with a slightly indented apex and clearly visible veins. First leaves: Three-sided mercury’s first leaves are opposite and ovate with round toothed margins. Leaves appear glossy and are green to copper in colour. Mature leaves: The mature leaves of three-seeded mercury have an alternate leaf orientation, and are similar in appearance to its younger leaves, only larger and with more prominent veins. Mature plant Stems: Erect, sparsely haired to hairy. Flowers: Male and female flowers are produced separately on the same plant (monoecious). They are green and clustered in leaf axils. The plant’s seedpods are deeply tri-lobed and contain the “three seeds” referred to in its common name. Seeds: Seeds are egg-shaped, range in length from 1.5–2 mm, and are tan coloured with spots. Roots: Taproot OFTEN MISTAKEN FOR I know it’s NOT … because … Pigweed species … three-seeded mercury has round cotyledons, a glossy bronze-green leaf colour, toothed leaf margins and clusters of greenish flowers at each axil. 206 WEED ID GUIDE FOR ONTARIO CROPS THREE-SEEDED MERCURY 1 4 5 1 Seedling with its orbicular (round) cotyledons and leaves with toothed margins 2 2 Older leaves with prominent veins and toothed margins 3 Alternate leaf orientation on the main stem 4 five glossy leaved, three-seeded mercury seedlings amongst redroot pigweed and common lamb'squarter during June. 5 Small flowers in greenish clusters 3 WEED ID GUIDE FOR ONTARIO CROPS 207 TEASEL Teasel (Dipsacaceae family) • Dipsacus fullonum L. EPPO Code: DIWSI Other Names: wild teasel, card thistle, gypsy-combs SPECIES INFORMATION Lifecycle: Biennial or monocarpic perennial Propagation: Reproduces only by seed. Emergence: The majority of seeds will germinate in early spring, but they can also germinate in the fall. Habitat: Teasel is most commonly found on field edges and in ditches, waste areas and pastures. Competitiveness: Teasel is rarely found in cultivated crops. More often it is found in pasture ground. The palatability of teasel is poor, making it an undesirable species in pastureland. IDENTIFICATION CLUES Seedling Cotyledons: Smooth, oval or round. Rosette leaves: Teasel’s rosette leaves are shiny green and oval or egg-shaped. They have toothed margins and are prickly when touched. Stem leaves: Its stem leaves are opposite, smaller than the rosette leaves and more pointed at the tip. They, too, are prickly when touched, and they have a row of spines on the mid-rib and short-toothed margins. Mature plant Stems: Teasel’s stem is green and covered in prickly whisker-like hairs. Flowers: Teasel has numerous, small, light purple flowers that grow in an egg-shaped spiny head that has long, slender, stiff, prickly bracts. Seeds: Its seeds are four–angled and light brown with parallel ridges. Each seed head produces hundreds of seeds. Roots: Taproot with secondary fibrous roots OFTEN MISTAKEN FOR I know it’s NOT … because … Thistles … although teasel is prickly to the touch, the rosette and stem leaves are oval with short-toothed margins, and are not deeply lobed or divided and sharp toothed like many of the common thistle species. 208 WEED ID GUIDE FOR ONTARIO CROPS TEASEL 1 3 2 4 1 Green, shiny and prickly rosette leaves in late April 2 Bolting plants, with pointed stem leaves oppositely oriented on a prickly stem in late June 3 The short-toothed leaf margins 4 Numerous small, light purple flowers within the egg-shaped and spiny heads 5 Mature seed heads 6 A large patch of teasel along a roadside 5 WEED ID GUIDE FOR ONTARIO CROPS 209 FIELD VIOLET Violet (Violaceae family) • Viola arvensis L. EPPO Code: VIOAR Other Names: field pansy, wild pansy SPECIES INFORMATION Lifecycle: Annual, winter annual. Propagation: Reproduces by seed. Emergence: Germination and emergence has been observed throughout the spring, summer and fall. Fall, however, is the most common time for emergence in cultivated fields. Habitat: Field violet is most often found in cereal crops, but it has also been found in soybean and corn crops. According to recent surveys, it is most prominent in south-central Ontario. Competitiveness: Field violet is not considered an overly competitive weed, especially in cereal crops where it is most often found. IDENTIFICATION CLUES Seedling Cotyledons: Round to ovate with a long stalk. Leaves First leaves: The leaves of seedlings and young plants are very small and have long stalks, rounded blades and a few shallow teeth. Mature leaves: Stem leaves are alternate, larger, oval or almost linear with a few rounded teeth. Mature field violet also has large appendages on the stem that resemble new leaf blades where leaves attach (stipules). Mature plant Stem: Field violet’s stem is erect, short and spreads with many branches. They may be covered in fine hair, appear fleshy or succulent and are up to 30 cm in length. Flowers: Pale yellow or white and yellow flowers, which grow on long, thin stalks, can resemble the flowers of cultivated pansy, but are much smaller. Field violet flowers from early May until midsummer. Seeds: Seedpods are split into three divisions and scatter numerous small, brownish seeds. Roots: Fibrous OFTEN MISTAKEN FOR Field violet is a very distinctive species that is not often confused with other weed species. It resembles a miniature pansy. 210 WEED ID GUIDE FOR ONTARIO CROPS FIELD VIOLET 1 3 2 4 1 Seedling plant with round to oval cotyledons 2 A seedling plant with rounded, toothed margins just prior to flowering in early May 3 A flowering plant found in a soybean field in late May 4 The pansy-like flower of field violet 5 A mature seed head explodes to disperse its seeds 5 WEED ID GUIDE FOR ONTARIO CROPS 211 QUACKGRASS Grass (Poaceae family) • Elytrigia repens (L.) Gould EPPO Code: AGGRE Other Names: twitch, twitch grass, couch grass, quitch grass, scutch grass SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces primarily by underground rhizomes, which produce new shoots when fragmented. Quackgrass also reproduces by seed, but less successfully. Emergence: Shoots will emerge from rhizomes throughout the season. Habitat: Common throughout Ontario, quackgrass is found in cultivated fields, pastures, lawns and gardens. Competitiveness: Agriculture and Agri-Food Canada research has shown that quackgrass densities of 20,000 plants/ac can result in a 15–18 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Auricles: Quackgrass auricles are whitish and clearly visible at the base of the leaf blade. Ligule: The Ligule is membranous, but very short and hard to see. Leaf blade: Leaf blades are generally hairless on both sides, sometimes fine hairy, especially the young ones. Leaf sheath: The leaf sheath and leaf sheath margins are generally hairless except for those at the base. Stem: Round Seed heads: Quackgrass’ seed heads are elongated, narrow spikes with two rows of spikelets, each containing 3–7 flowers. Roots and underground parts: Quackgrass produces numerous whitish-brown rhizomes that grow horizontally and can produce new shoots. Very fine fibrous roots grow from the rhizome nodes. OFTEN MISTAKEN FOR I know it’s NOT … because … Wire-stemmed muhly … quackgrass leaves have auricles, whereas those of wire-stemmed muhly do not. Also, wire-stemmed muhly has very wiry stems and short, thin leaves. 212 WEED ID GUIDE FOR ONTARIO CROPS QUACKGRASS 1 4 2 5 1 Quackgrass rhizome 2 Auricles at the base of the leaf and the clasp the stem 3 The elongated narrow spike with spikelets in two rows 4 Membranous ligule 5 A small quackgrass patch in early June 3 WEED ID GUIDE FOR ONTARIO CROPS 213 WILD OATS Grass (Poaceae family) • Avena fatua L. EPPO Code: AVEFA Other Names: black oats SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Typically, wild oats emerges in the spring, but timing of emergence is widely variable due to differences in soil texture, topography, moisture and temperature. Habitat: Wild oats is most commonly found in areas of the province where spring cereals figure prominently in the crop rotation. It is less common in crop rotations with corn and soybeans, mainly due to seedbed preparation timing and effective herbicide use. Competitiveness: When densities approach 280,000 plants/ac, spring cereal yield losses can be as high as 25 percent. Of more concern is the fact that the seeds of wild oats are difficult to separate from harvested cereal grain. Resistance: There are wild oats populations in Ontario that are resistant to Group 1 (e.g. fenoxaprop-p-ethyl) herbicides. IDENTIFICATION CLUES Auricles: None Ligule: Membranous Leaf blade: Wild oat leaf blades are hairless. Young seedling leaves will twist counterclockwise, which differentiates it from other cereal plants that twist clockwise instead. Leaf blade margins have a series of short hairs, particularly close to their base. Leaf sheath: Leaf sheath and leaf sheath margins are generally hairless. Stem: Round Seed heads: Wild oats seed heads are large panicles with slender branches and spikelets. They have two large, papery glumes, which usually contain 2 to 4 seeds. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Volunteer cereals … generally, wild oats grows in patches. The weed’s young seedling leaves twist in a counterclockwise manner, while the young seedling leaves of most cereal plants do not. Instead, they twist clockwise. Wild oats does not have auricles, whereas wheat, barley and triticale do. 214 WEED ID GUIDE FOR ONTARIO CROPS WILD OATS 1 3 2 4 1 Membranous ligule 2 The hairless leaf blade 3 The counterclockwise twisting of young seedling leaves 4 The large panicle of wild oats, reminiscent of cultivated oats 5 Whole plant at the reproductive stage 5 WEED ID GUIDE FOR ONTARIO CROPS 215 DOWNY BROME Grass (Poaceae family) • Bromus tectorum L. EPPO Code: BROTE Other Names: cheat, cheat grass, cheat grass brome, downy chess, slender chess SPECIES INFORMATION Lifecycle: Annual or winter annual. Propagation: Reproduces by seed. Emergence: Most seeds germinate in the autumn, but some also germinate in the spring. Habitat: Downy brome grows throughout Ontario on all soil types. Most commonly, though, it grows on roadsides, in waste places, on beaches and in cereal field crops. Competitiveness: Field studies in the United States have shown as much as a 92 percent yield loss in winter wheat when competing with a 200 plant/m2 density when it emerges prior to wheat. IDENTIFICATION CLUES Auricles: None Ligule: Membranous Leaf blade: The leaf blades of downy brome have soft, short, dense hairs on both surfaces. Leaf sheath: Leaf sheaths are rounded and densely haired with short, soft hairs that are white with a tinge of red at the base. Stem: In good soil conditions, downy brome’s stem grows 20–60 cm tall. In gravelly soils, it grows less than 20 cm high. Seed heads: Downy brome flowers from May to August. The seed head is a long panicle with many soft, slender and dropping branches. Spikelets have long awns and 2–7 florets. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Chess … downy brome has a much hairier leaf sheath and its spikelet has long awns and much thinner seeds. 216 WEED ID GUIDE FOR ONTARIO CROPS DOWNY BROME 1 4 5 1 A membranous ligule 2 A leaf blade with short, dense hairs 2 3 The densely short-haired leaf sheath 4 A clump of downy brome out in flower 5 A close-up of a seed head 3 WEED ID GUIDE FOR ONTARIO CROPS 217 CHESS Grass (Poaceae family) • Bromus secalinus L. EPPO Code: BROSE Other Names: cheat, cheat grass SPECIES INFORMATION Lifecycle: Annual or winter annual. Propagation: Reproduces by seed. Habitat: Occurs in fields and waste areas throughout agricultural areas in Ontario, but is most common on heavier textured soils. Competitiveness: Field studies in the United States have shown 28–48 percent yield loss when winter wheat was competing with a 25 plants/m2 average density of Bromus secalinus. IDENTIFICATION CLUES Leaves Auricles: None Ligule: Membranous, prominent, 1–3 mm long, sometimes ragged at the top. Leaf blade: Either smooth or softly hairy on one or both surfaces. Leaf sheath: 1–3 mm long; lower leaf sheaths are smooth or hairy, with united margins nearly to the top, upper leaf sheaths are split with overlapping or separate margins. Mature plant Stem: 1–4 stems from 1 root; smooth but finely hairy on the nodes; 30–90 cm in height. Seedheads: In stiff, nearly erect branches; spikelets have a firm, plump appearance, each with 5–15 florets; short awns, sometime absent; flowers from June to August. OFTEN MISTAKEN FOR I know it’s NOT … because … Downy brome ... Chess is distinguished by its firm, plump spikelets, its smooth stems with finely hairy nodes, and the combination of lower leaf sheathes closed and upper leaf sheaths split with overlapping margins. 218 WEED ID GUIDE FOR ONTARIO CROPS CHESS 3 1 2 1 The softly hairy upper surface of chess’s leaf blade 2 The membranous ligule of chess 4 3 Chess’s finely hairy stem node 4 The spikelet of chess with short awns 5 Mature seedheads above a winter wheat crop during July 5 WEED ID GUIDE FOR ONTARIO CROPS 219 LONG-SPINED SANDBUR Grass (Poaceae family) • Cenchrus longispinus (Hack.) Fernald EPPO Code: CCHPA Other Names: bur grass SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Long-spined sandbur emerges in the spring with the majority of plants emerging in May. It sometimes can, however, germinate into the summer months. Habitat: Most commonly, long-spined sandbur is found in sandy soils throughout southern Ontario. Competitiveness: University of Guelph (Ridgetown campus) research has shown that where long-spined sandbur is left uncontrolled at typical field densities, it can inflict yield losses as high as 30% in soybeans and 40 percent in corn (Soltani et al., 2009, 2010). IDENTIFICATION CLUES Auricles: None Ligule: hairy, short (1 mm) Leaf blade: Long-spined sandbur leaf blades are mostly hairless, but will feel rough when the blade is run between the thumb and index finger in one direction. Leaf sheath: The leaf sheath is split with overlapping margins that are membranous. Although they are hairless when young, they may be sparsely haired when older. There is a tuft of hairs at the collar (junction between leaf sheath and blade). Stem: Long-spined sandbur stems are flat and are covered with many plants. Near the base of the plant, stems exhibit a reddish tinge. Seed heads: Seed heads grow in rows with spiny burs that appear in a spike-like formation. The spiny burs have extremely sharp spines that will anchor to clothing and/or skin when walking through the field. Roots: Roots are fibrous with a distinct bur that is easily found close to the surface of the soil. OFTEN MISTAKEN FOR I know it’s NOT … because … Yellow foxtail … long-spined sandbur lacks the short, wiry hairs at the bottom of the leaf blade base. Barnyardgrass … long-spined sandbur has a hairy ligule, while barnyardgrass has no ligule at all. 220 WEED ID GUIDE FOR ONTARIO CROPS LONG-SPINED SANDBUR 3 1 2 1 A young plant in the early tillering stage 2 A bur attached to the fibrous root that is easily found near the soil surface 4 3 A cluster of seedling plants found in a sandy southern Ontario field 4 The spiked seed head containing a group of spiny burs WEED ID GUIDE FOR ONTARIO CROPS 221 SMOOTH CRABGRASS Grass (Poaceae family) • Digitaria ischaemum (Schreb,) Muhl. EPPO Code: DIGIS Other Names: finger grass, small crabgrass SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Typically, smooth crabgrass is one of the later-emerging annual grasses. Habitat: Smooth crabgrass is commonly found in cultivated fields throughout Ontario. It is also common in lawns. Competitiveness: Agriculture and Agri-Food Canada research has shown that smooth crabgrass densities of 20,000 plants/ac can result in a 3 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Auricles: None Ligule: Membranous Leaf blade: As its name suggests, the leaf blade of smooth crabgrass is smooth on both sides. Leaf sheath: Smooth crabgrass’ leaf sheath is also smooth and its margins are hairless. There are a few hair near the collar on the basal leaves (1st to 4th). Stem: Its stem is round, and typically it has a prostrate growth pattern. Seed heads: Seed heads are finger-like and covered in several thin spikes. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Large crabgrass … large crabgrass is extremely hairy, while smooth crabgrass is mostly hairless. 222 WEED ID GUIDE FOR ONTARIO CROPS SMOOTH CRABGRASS 3 1 4 2 1 The hairless leaf sheath and margins of smooth crabgrass 2 A membranous ligule 3 The hairless leaf blade 4 The finger-like seed head with several thin and slender spikes WEED ID GUIDE FOR ONTARIO CROPS 223 LARGE CRABGRASS Grass (Poaceae family) • Digitaria sanguinalis (L.) Scop. EPPO Code: DIGSA Other Names: finger grass, hairy crabgrass, tumbleweed SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Usually, large crabgrass is one of the last annual grass species to emerge. It is considered a mid- to late-season weed. Habitat: Large crabgrass is commonly found in cultivated fields and lawns throughout Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that large crabgrass densities of 20,000 plants/ac can result in 3 percent yield losses in corn and soybeans. Resistance: There are large crabgrass populations resistant to Group 1 (e.g. quizalofop, sethoxydim) herbicides in Ontario. IDENTIFICATION CLUES Auricles: None Ligule: Membranous Leaf blade: Hairy on both sides. Leaf sheath: Hairy, although the margin of the leaf sheath is hairless. Stem: Round Seed heads: Finger-like with several thin and slender spikes. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Proso millet … large crabgrass has a membranous ligule, but proso millet has a hairy ligule. Smooth crabgrass … large crabgrass is extremely hairy, but smooth crabgrass is relatively hairless. Witchgrass … large crabgrass has a membranous ligule, but witchgrass has a hairy ligule. 224 WEED ID GUIDE FOR ONTARIO CROPS LARGE CRABGRASS 1 3 2 4 1 Membranous ligule 2 The hairy leaf sheath margin 3 The hairy upper surface of the leaf blade 4 The long, spiked seedhead 5 The finger like seed head with several thin and slender spikes 5 WEED ID GUIDE FOR ONTARIO CROPS 225 BARNYARD GRASS Grass (Poaceae family) • Echinochloa crus-galli (L.) Beauv. EPPO Code: ECHCG Other Names: summer grass, water grass SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed Emergence: An early to mid-season emerging species Habitat: Barnyard grass is a very common annual grass found in a variety of soil types in cultivated fields, roadsides, waste places and sometimes lawns throughout Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that barnyard grass densities of 20,000 plants/ac can result in a 7–12 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Auricles: None Ligule: None Leaf blade: Both the upper and lower surface of the leaf blade is hairless. Leaf sheath: The sheath and its margins are both hairless. Stem: Flat Seed heads: Barnyard grass seed heads have a central axis with lateral branches that contain dense clusters of spikelets. The seedhead turns purplish-green to almost black at maturity. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Fall panicum … barnyard grass has no ligule. Yellow foxtail … barnyard grass has no ligule, nor clusters of short kinky hairs at the base of its leaf blade. 226 WEED ID GUIDE FOR ONTARIO CROPS BARNYARD GRASS 3 1 2 1 The flat and hairless leaf sheath and hairless margins 2 The absence of a ligule 4 3 Hairless leaf blade on both the upper and lower surface 4 Seedhead WEED ID GUIDE FOR ONTARIO CROPS 227 WIRE-STEMMED MUHLY Grass (Poaceae family) • Muhlenbergia frondosa (Poir.) Fern. EPPO Code: MUHFR SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces primarily by underground rhizomes and seeds. Emergence: Shoots emerge from rhizomes throughout the season. Habitat: Wire-stemmed muhly is most commonly found in southern and eastern Ontario, but originates in the rich soil found in flood plains, along riverbanks and on shorelines. It also grows in cultivated fields, pastures, lawns and gardens. Competitiveness: University of Guelph (Ridgetown campus) research has shown that when typical field densities of wire-stemmed muhly are poorly controlled in field corn, yield losses of nearly 20 percent can be observed. IDENTIFICATION CLUES Auricles: None Ligule: While the wire-stemmed muhly ligules are membranous, they have an outer margin that is ragged, which makes it appear hairy. Leaf blade: The leaf blades of wire-stemmed muhly are thin, long and hairless on both sides. Leaf sheath: The leaf sheath and leaf sheath margins are hairless. Stem: Round Seed heads: Seed heads are comprised of small, soft and somewhat silky panicles. Roots: Rhizomes are located just below the soil’s surface, usually in a mangled clump. They have distinctively short, scaly and brown to pinky-purple segments that are branched and break off very easily. OFTEN MISTAKEN FOR I know it’s NOT … because … Quackgrass … wire-stemmed muhly lacks auricles, and has very wiry stems with long, thin leaves. Most distinctively, wire-stemmed muhly has pinky-purple rhizomes that are short, scaly and brittle. 228 WEED ID GUIDE FOR ONTARIO CROPS WIRE-STEMMED MUHLY 1 3 2 1 A dense patch of wire-stemmed muhly in corn 2 A plant just prior to heading 4 3 The distinctive short, scaly and pinky-purple rhizomes 4 A mature seed head with soft, somewhat silky panicles WEED ID GUIDE FOR ONTARIO CROPS 229 WITCHGRASS Grass (Poaceae family) • Panicum capillare L. EPPO Code: PANCA Other Names: tumble grass, tickle grass, panic grass, old witch grass, hair grass, capillary SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed Emergence: Witchgrass is an early to mid-season germinating annual grass species. Habitat: It is found throughout the province, but more typically in cultivated fields in central and south-central Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that witchgrass densities of 20,000 plants/ac can result in a 4–5 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Auricles: None Ligule: Hairy Leaf blade: Densely hairy on both sides Leaf sheath: The leaf sheath of witchgrass is extremely hairy, as is the leaf sheath margin. Stem: Round and hairy Seed heads: Witchgrass’ seed head is a “fluffy” panicle with numerous fine branches resembling arterial capillaries. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Fall panicum … witchgrass has a hairy stem and hairy leaf sheath margin while fall panicum is almost entirely smooth. Large crabgrass … witchgrass has a hairy ligule while large crabgrass has a membranous ligule. Proso millet … the leaf blade of witchgrass is extremely hairy on both sides. 230 WEED ID GUIDE FOR ONTARIO CROPS WITCHGRASS 1 4 5 1 A densely hairy leaf sheath and margins 2 2 A hairy ligule 3 The leaf blade, which is hairy on both sides 4 The round and densely hairy stem 5 The seed head is a fluffy panicle with numerous fine branches 3 WEED ID GUIDE FOR ONTARIO CROPS 231 FALL PANICUM Grass (Poaceae family) • Panicum dichotomiflorum Michx. EPPO Code: PANDI Other Names: smooth panicum, smooth witch grass, spreading panic grass SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed Emergence: Fall panicum is one of the last annual grass species to emerge in the spring. Habitat: It is most commonly found in southwestern Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that fall panicum densities of 20,000 plants/ac can result in a 10 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Auricles: None Ligule: Hairy Leaf blade: Very young seedlings can be densely hairy, but will become less hairy with age. Older seedling plants feel smooth and hairless, but do contain a very prominent midrib. Leaf sheath: The margins of the sheath are hairless. Stem: Round Seed heads: Seed heads appear as several branches of panicles that contain seed that is yellow to brown in colour. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Green foxtail … fall panicum does not have hairy leaf sheath margins. Giant foxtail … the upper leaf blade of fall panicum is hairless and it does not have hairy leaf sheath margins. Proso millet … fall panicum does not have hairy stems or hairs along the base of the leaf blade’s margin Witchgrass … fall panicum isn’t as hairy as witchgrass, which is extremely hairy. Also, the leaf blade of witchgrass lacks the prominent midrib that fall panicum has. 232 WEED ID GUIDE FOR ONTARIO CROPS FALL PANICUM 1 4 2 5 1 The leaf sheath margins are hairless 2 A hairy ligule 3 The seedling leaf sheath and blade can be densely hairy 4 Older leaf blade is generally hairless, but has a prominent midrib 5 The seedhead contains several branched panicles 3 WEED ID GUIDE FOR ONTARIO CROPS 233 PROSO MILLET Grass (Poaceae family) • Panicum miliaceum L. EPPO Code: PANMI Other Names: panic millet, proso, wild proso millet, broom-corn millet, millet SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Generally, proso millet is considered an early to mid-season germinating annual grass. Its relatively large seed allows it to emerge from greater soil depths, which results in a longer germination period. Habitat: Proso millet can be found throughout the province, but is most common in south-central Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that proso millet densities of 20,000 plants/ac can result in a 10–12 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Auricles: None Ligule: Hairy Leaf blade: Both the upper and lower surface of the leaf blade are smooth and hairless. Leaf sheath: The leaf sheath and its margin are hairy. Stem: Round Seed heads: Proso millet’s seed head is bristly, spiked and typically about 4–10 cm long. It is about half the size of giant foxtail’s seed head and contains smaller seeds than that of yellow foxtail. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Large crabgrass … proso millet has a hairy ligule and large crabgrass has a membranous ligule. Witch grass … the leaf blade of proso millet is usually hairless and has prominent veins running parallel to the leaf blade margins. 234 WEED ID GUIDE FOR ONTARIO CROPS PROSO MILLET 1 3 2 4 1 The extremely hairy leaf sheath and margin 2 Hairy ligule 3 Typically, proso millet’s leaf blade is hairless, but it can have sparse hairs on upper and lower leaf surfaces 4 Proso millet can have two different seed head types, a closed broomlike panicle or a more wide-open panicle 5 There are typically six different seed colours that exist (reddish/brown is shown) including white, yellow, green, orange and black 5 WEED ID GUIDE FOR ONTARIO CROPS 235 BLUEGRASS SPECIES Grass family (Poaceae family) • Poa spp. EPPO Code: POASP Other Names: June grass, summer grass SPECIES INFORMATION Lifecycle: Most bluegrass species are perennial, except annual bluegrass, which is annual. Propagation: Whether annual or perennial, all bluegrass species reproduce by seed and rhizomes. IDENTIFICATION CLUES Auricles: Absent Ligule: Membraneous Leaf blade: The plant’s leaf blade is narrow, smooth and folded lengthwise with a bowshaped tip. Best advice: It is very difficult to identify specific bluegrass species. Generally, if you see a grassy species that has a membraneous ligule and leaf blades that are narrow, smooth and folded with a bow-shaped tip (like the front of boat) then it could possibly be a Poa species. Oftentimes, if a farmer or agronomist thinks they have a bluegrass species, they will wait until the specimen has headed and then send it to the Ontario Agriculture College herbarium to have it appropriately identified. In the past we have commonly had confirmation of the following four species throughout cultivated fields in Ontario: annual bluegrass, Canada bluegrass, fowl meadow grass and roughstalk bluegrass. To contact the OAC Herbarium, call 519-824-4120 Ext. 58581. 236 WEED ID GUIDE FOR ONTARIO CROPS BLUEGRASS SPECIES 4 1 5 1 The membraneous ligule 2 2 A small tuft of annual blue grass found on heavy clay in early May 3 Several tufts of annual blue grass starting to flower and with their narrow, folded and bow-shaped leaf blade tips 4 A clump of rough stalk blue grass during mid-May 5 A heavy infestation of annual blue grass that has headed and is competing with winter wheat 3 WEED ID GUIDE FOR ONTARIO CROPS 237 GIANT FOXTAIL Grass (Poaceae family) • Setaria faberi R.A.W. Herrm. EPPO Code: SETFA Other Names: bottle brush, bottle grass, bristle grass, millet, pigeon grass, wild millet SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Typically, giant foxtail is one of the first annual grass species to emerge in the spring. Usually, though, it emerges after broadleaf weeds, like lambsquarter and pigweed. Habitat: Although it can be found throughout the province, it is most commonly found in cultivated fields in southwestern Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that yellow foxtail densities of 20,000 plants/ac can result in a 10–12 percent yield loss in corn and soybeans. Resistance: A number of populations are resistant to Group 2 (e.g. imazethapyr) herbicides in Ontario. IDENTIFICATION CLUES Auricles: None Ligule: Hairy Leaf blade: The upper surface of giant foxtail’s leaf blade is hairy, while the lower surface is hairless. Leaf sheath: The margins of the sheath are hairy. Stem: Round Seed heads: Giant foxtail’s seed head is bristly and spiked. Typically, its seed head is twice the length of that of green foxtail. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Fall panicum … giant foxtail’s leaf blade has a hairy upper surface and a hairy leaf sheath margin. Fall panicum, on the other hand, has neither. Green foxtail … the upper leaf blade surface of giant foxtail is hairy, while green foxtail’s is not. Large crabgrass … giant foxtail has a hairy ligule while that of large crabgrass is membranous. 238 WEED ID GUIDE FOR ONTARIO CROPS GIANT FOXTAIL 3 1 2 1 A hairy ligule 2 The hairy leaf sheath margin 3 The hairy upper surface of the leaf blade 4 4 The long, spiked seed head WEED ID GUIDE FOR ONTARIO CROPS 239 YELLOW FOXTAIL Grass (Poaceae family) • Setaria pumila (Poir.) Roem. & Schult. EPPO Code: SETLU Other Names: bottle brush, bottle grass, bristle grass, millet, pigeon grass, wild millet SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Yellow foxtail typically emerges later than other annual grass species (e.g. green foxtail, witchgrass) and around the same time as eastern black nightshade. Habitat: It is found mainly in cultivated fields throughout the province. Competitiveness: Agriculture and Agri-Food Canada research has shown that yellow foxtail densities of 20,000 plants/ac can result in a 5 percent yield loss in corn and soybeans. Resistance: A number of populations are resistant to Group 5 (e.g. atrazine) herbicides in Ontario. IDENTIFICATION CLUES Auricles: None Ligule: Hairy Leaf blade: The base of yellow foxtail’s leaf blade is covered with a number of straggly hairs that are roughly 1–2 cm in length. Leaf sheath: The margins of the sheath are hairless. Stem: Young seedling plants appear to have a round stem, but as the plant gets older the stem is distinctively flat. Of the common annual grasses in Ontario, only yellow foxtail and barnyardgrass have flat stems. Seed heads: Yellow foxtail has a spiked seed head, typically 4–6 cm long, with larger seeds than that of other foxtail species, but shorter bristles. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Barnyardgrass … yellow foxtail has a hairy ligule, but barnyardgrass has no ligule at all. Large crabgrass … yellow foxtail has a hairy ligule. Proso millet … yellow foxtail has a flattened and hairless leaf sheath. Witchgrass … yellow foxtail does not have a hairy stem. 240 WEED ID GUIDE FOR ONTARIO CROPS YELLOW FOXTAIL 1 3 4 1 Yellow foxtail’s hairy ligule 2 2 The straggly hairs at the base of the leaf blade 3 The flat stem and hairless leaf sheath margin 4 The spiked seed head with its larger seeds and short, reddish dark bristles WEED ID GUIDE FOR ONTARIO CROPS 241 GREEN FOXTAIL Grass (Poaceae family) • Setaria viridis (L.) P. Beauv. EPPO Code: SETVI Other Names: bottle brush, bottle grass, bristle grass, millet, pigeon grass, wild millet SPECIES INFORMATION Lifecycle: Annual Propagation: Reproduces by seed. Emergence: Typically, green foxtail is one of the first annual grass species to emerge in the spring, but it usually emerges after broadleaf weeds, like lamb’s quarters and pigweed. Habitat: Green foxtails is probably the most common of the foxtail species. It is mainly found in cultivated fields throughout Ontario. Competitiveness: Agriculture and Agri-Food Canada research has shown that green foxtail densities of 20,000 plants/ac can result in up to a 7 percent yield loss in corn and soybeans. Resistance: A number of populations are resistant to Group 2 (e.g. imazethapyr) herbicides in Ontario. IDENTIFICATION CLUES Auricles: None Ligule: Hairy Leaf blade: Both the upper and lower surface of the leaf blade is smooth and hairless. Leaf sheath: The margins of the sheath are hairy. Stem: Round Seed heads: Green foxtail’s seed head is typically 4–10 cm long, bristly and spiked. About half the size of giant foxtail’s seed head, green foxtail also produces smaller seeds than those of yellow foxtail. Roots: Fibrous OFTEN MISTAKEN FOR I know it’s NOT … because … Fall panicum … green foxtail has a hairy leaf margin and fall panicum does not. Giant foxtail … the upper and lower leaf blade surface of green foxtail is hairless. 242 WEED ID GUIDE FOR ONTARIO CROPS GREEN FOXTAIL 1 3 2 4 1 A seedling green foxtail 2 Hairy ligule 3 A hairless leaf blade on both the upper and lower surface 4 The hairy leaf sheath margin 5 The spiked seed head with its smaller seeds (compared to yellow foxtail) and shorter length (compared to giant foxtail) 5 WEED ID GUIDE FOR ONTARIO CROPS 243 YELLOW NUTSEDGE Grass (Sedge family) • Cyperus esculentus L. EPPO Code: CYPES Other Names: chufa, earth almond, ground almond, nut grass, yellow nut-grass, northern nut-grass SPECIES INFORMATION Lifecycle: Perennial Propagation: Reproduces by seed, rhizomes and tubers. While the rhizomes allow a patch to expand, the tubers overwinter to produce new plants the following season. In Ontario conditions, seeds rarely produce new seedlings. Emergence: Throughout the season, shoots emerge from both the tubers and rhizomes. Habitat: Yellow nutsedge is common throughout Ontario in cultivated fields, pastures, lawns and gardens. Competitiveness: Agriculture and Agri-Food Canada research has shown that yellow nutsedge densities of 20,000 plants/ac can result in a 7 percent yield loss in corn and soybeans. IDENTIFICATION CLUES Main tip: To identify yellow nutsedge, feel the base of the plant with your thumb and index finger. You should feel three distinct sides that form a triangle. Leaf blade: The leaf blades of yellow nutsedge are hairless with prominent midribs; leaves are numerous at the base of the plant. Leaf sheath: Leaf sheaths are closed and form a triangle shape around the stem. Seed heads: Seed heads appear as a cluster of yellowish to brownish branches at the tip of the stem. Roots: Yellow nutsedge plants produce extensive, whitish to light brown rhizomes. Tubers: Located at the tip of the rhizome, newly formed tubers are white, but turn dark brown as they mature. Yellow nutsedge tubers are edible and sometimes referred to as “tiger nuts.” 244 WEED ID GUIDE FOR ONTARIO CROPS YELLOW NUTSEDGE 4 1 5 2 1 A newly emerged seedling shoot originating from an overwintered tuber 2 A hairless leaf blade 3 The triangular base from which numerous leaves arise 4 A seed head with a cluster of yellowish to brownish branches 5 A formation of tubers from the tip of the rhizome. Young tubers are white, while the more mature tubers are dark brown 3 WEED ID GUIDE FOR ONTARIO CROPS 245 CITATIONS BIENNIAL WORMWOOD Nelson, E.A. and G.O. Kegode. 2006 Biennial wormwood (Artemisia biennis) competiton with soybean (Glycine max). Phytoprotection. 86:125-132. BUTTERCUPS Buttercup (Ranunculus spp). (n.d). In University of Illinois Veterinary Medicine Library. Retrieved December 3, 2015, from http://www.library.illinois.edu/vex/toxic/butcup/ butcup.htm CHICORY Hall, M. (n.d.). In: Forage Chicory. PennState Extension. Retrieved December 8, 2015, from http://extension.psu.edu/plants/crops/forages/species/forage-chicory University of Nebraska-Lincoln. (n.d.). In: Root of the matter. University of NebraskaLincoln Research Media. Retrieved December 8, 2015, from http://weedscience.unl. edu/currentTopics/2013ChicoryRW.pdf CINQUEFOIL Werner, P.A. and J.D. Soule. 1976. The biology of Canadian weeds. 18. Potentilla recta L., P. norvegica L. and P. argentea L. Canadian Journal of Plant Science, 56: 591–603. CORN SPURRY Weaver, S.E. and J.A. Ivany. 1998. Economic thresholds for wild radish, wild oat, hempnettle and corn spurry in spring barley. Canadian Journal of Plant Science, 78: 357-361. Milberg, P. and E. Hallgren. 2004. Yield loss due to weeds in cereals and its large-scale variability in Sweden. Field Crops Research. 86: 199–209. DOCKS Pye, A. and L. Anderson. 2009. Time of emergence of Rumex crispus L. as affected by dispersal time, soil cover, and mechanical disturbance. Acta Agriculturae Scandinavica Section B Soil and Plant Science, 59: 500–505. DOGBANE United States Department of Agriculture. (2006). Hemp Dogbane (Apocynum cannabinum). Retrieved February 2, 2016, from http://www.ars.usda.gov/Research/ docs.htm?docid=9938 DOG STRANGLING VINE DiTommaso, A., Lawlor, F.M and S.J. Darbyshire. 2005. The Biology of Invasive Alien Plants in Canada. 2. Cynanchum rossicum (Kleopow) Borhidi [= Vincetoxicum rossicum (Kleopow) Barbar.] and Cynanchum louiseae (L.) Kartesz & Gandhi [= Vincetoxicum nigrum (L.) Moench]. Canadian Journal of Plant Science, 58: 401-413. 246 WEED ID GUIDE FOR ONTARIO CROPS GARLIC MUSTARD Cavers, P.B., Heagy, M.I. and R.F. Kokron. 1970. The biology of Canadian Weeds.: 35. Alliaria petiolata (M. Bieb.) Cavara and Grande. Can. J. Plant Sci. 59(1): 217–229. GROUND-CHERRY, CLAMMY Abdullahi, A.E. and P. B. Cavers. 1997. Factors affecting regeneration from root fragments in two Physalis species. Phytoprotection, 78: 23–33. Ohio State University Extension, 2015 https://www.oardc.ohio-state.edu/ weedguide/singlerecord.asp?id=710 Government of Canada, 2015 http://www.cbif.gc.ca/eng/species-bank/canadianpoisonous-plants-information-system/all-plants-scientific-name/physalisperuviana/?id=1370403266966 HORSETAIL Kingsbury, J. M. 1964. Poisonous plants of the United States and Canada. Prentice-Hall Inc., Englewood Cliffs, N.J., USA. 626 pp. JIMSONWEED Hagood , E.S. Jr., Bauman , T.T. , Williams , J.L. Jr. and M.M. Schreiber. 1981. Growth analysis of soybeans (Glycine max) in competition with jimsonweed (Factors affecting regéneration from root fragments in two Physalis species. ) Weed Science, 29: 500– 504. KNAPWEED Watson, A.K. and A.J. Renney. 1974. The biology of Canadian weeds. 6. Centaurea diffusa and C. maculosa. Cananadian Journal of Plant Science, 54: 687-701. Pollock, J.L., Callaway, R.M., Thelen G.C. and W.E. Holben. 2009. Catechin–metal interactions as a mechanism for conditional allelopathy by the invasive plant Centaurea maculosa. Journal of Ecology, 97: 1234–1242. KOCHIA Manthrey, F.A., Hareland, G.A., Zollinger, R.K. and D.J. Huseby. 1996. Kochia (Kochia scoparia) interference with oat (Avena sativa). Weed Technology, 10: 522-525. KUDZU Frye, M. (n.d.). Lessons learned from six year of kudzu research. Retrieved December 7, 2015, from https://nysipm.cornell.edu/sites/nysipm.cornell.edu/files/shared/ documents/kudzu.pdf MULLEIN Gross, K.L. and P.A. Werner. 1977. The biology of Canadian weeds. 28. Verbascum thapsus L. and Verbascum blattaria L. Canadian Journal of Plant Science, 58: 401–413. WEED ID GUIDE FOR ONTARIO CROPS 247 NIGHT-FLOWERING CATCHFLY Boström, U., Milber, P. and H. Fogelfors. 2003. Yield loss in spring-sown cereals related to the weed flora in the spring. Weed Science, 51: 418–424. NIGHTSHADE, EASTERN BLACK Anonymous http://www.cbif.gc.ca/eng/species-bank/canadianpoisonous-plants-information-system/all-plants-common-name/blacknightshade/?id=1370403267063 NIPPLEWORT Fiveland, T. J. 1974. The competition between swedes or carrots and annual weeds. Meld. Nor. Landbrukshogsk 53: 21. 15 pp. PALMER AMARANTH Legleiter, T and B. Johnson. 2013 Palmer Amaranth Biology, Identification, and Management. Purdue Extension. Retrieved December 7, 2015, from https://www. extension.purdue.edu/extmedia/WS/WS-51-W.pdf PEPPERGRASS Merker, A., Eriksson, D. and N. Bertholdsson. 2010. Barley yield increases with undersown Lepidium campestre. Acta Agriculturae Scandinavica Section B Soil and Plant Science, 2010. 60: 269–273. Swan, D.G. 1971. Competition of blue mustard with winter wheat. Weed Science, 19: 340–342. SHEPHERD’S-PURSE Milberg, P. and E. Hallgren. 2004. Yield loss due to weeds in cereals and its large-scale variability in Sweden. Field Crops Research, 86: 199–209. SPOTTED WATER HEMLOCK Mulligan, G.E. and D.B. Munro. 1980. The biology of Canadian weeds. 48.Cicuta maculata L., C. douglasii (DC.) Coult. & Rose and C. virosa L. Canadian Journal of Plant Science, 61:93–105. Mulligan, G.E. and D.B. Munro. op. cit. SCARLET PIMPERNEL Mulligan, G.E. and D.B. Munro. 1990. Poisonous Plants of Canada. Publication 1842/E. Government of Canada. pp 41. TANSY RAGWORT Lawlis, P. (1998, March 30). Poisoning of Horses by Plants. Retrieved July 16, 2015, from http://www.omafra.gov.on.ca/english/livestock/horses/facts/poison. htm#TansyRagwort 248 WEED ID GUIDE FOR ONTARIO CROPS WILD OATS Satorre, E.H. 2005. Barley (Hordeum vulgare) and wild oat (Avena fatua) competition is affected by crop and weed density. Weed Technology, 19: 790–795. WILLOWHERB Przepiorkowski T and SF, Gorski, 1994. Influence of rye (Secale cereale) plant residues on germination and growth of three triazine-resistant and susceptible weeds. Weed Technology, 8: 744–747. WOODSORREL, CREEPING YELLOW Doust, L.L., Mackinnon, A. and J.L. Doust. 1985. The biology of Canadian weeds. 71. Oxalis stricta L., O. corniculata L., O. dillenii Jacq. ssp. dillenii and O. dillenii Jacq. ssp. filipes (Small) Eiten. Canadian Journal of Plant Science 65:691–709. YELLOW EVENING-PRIMROSE Hall, I. V., Stener, E., Threadgill, P. and Jones, R. W. 1988. The biology of Canadian weeds. 84. Oenothera biennis L. Canadian Journal of Plant Science 68: 163–173. WEED ID GUIDE FOR ONTARIO CROPS 249 INDEX EPPO Codes: UPPER CASE • Common Names: Title Case Latin Names: Sentence case • Other names: lower case A ABUTH 120 Abutilon theophrasti 120 Acalypha rhomboidea 206 ACCRH 206 AGGRE 212 ALAPE 140 Alliaria petiolata 140 AMAPO 168 Amaranth, Palmer 166 Amaranthus palmeri 166 Amaranthus powellii 168 Amaranthus retroflexus 170 Amaranthus tuberculatus 172 AMARE 170 AMARU 172 AMBEL 26 Ambrosia artemisiifolia 26 Ambrosia trifida 28 AMBTR 28 Anagallis arvensis 192 ANGAR 192 Angelica 12 Angelica atropurpurea 12 angélique 12 ANKAT 12 Annual Fleabane 48 Annual Sow-Thistle 68 ANRSY 14 Anthriscus sylvestris 14 APCAN 74 Apocynum androsaemifolium 74 apple-of-sodom 160 Arctium minus 30 ARFMI 30 ARTBI 32 250 Artemisia biennis 32 Asclepias syriaca 126 ASCSY 126 Atriplex patula 90 Atriplex, Spreading 90 ATXPA 90 AVEFA 214 Avena fatua 214 B baby’s breath 118 balsam apple 98 bamboo weed 106 Barnyard Grass 226 beaver poison 16 Bedstraw, Smooth 118 bee nettle 130 beggar’s-ticks 34 beggar tick 142 Beggarticks, Tall 34 belevedere 96 Bidens vulgata 34 BIDVU 34 Biennial Wormwood 32 Bindweed, Field 138 Bindweed, Hedge 136 bird-seed 62 Bird’s-Eye Speedwell 84 bird’s-eye veronica 84 bird’s-nest 18 bird vetch 114 bitterweed 50 black bindweed 200 Black Medick 108 black nightshade 162 black oats 214 Bladder Campion 180 WEED ID GUIDE FOR ONTARIO CROPS blue dairy 40 blue devil 4 Bluegrass Species 236 blue sailors 40 blue-thistle 4 Blueweed 4 blunt-leaved dock 204 bottle brush 238, 240, 242 bottle grass 238, 240, 242 bristle grass 238, 240, 242 Broad-Leaved Plantain 188 Brome, Downy 216 Bromus secalinus 218 Bromus tectorum 216 broom-corn millet 234 BROSE 218 BROTE 216 brown berried nightshade 164 buckhorn plantain 186 Buckwheat, Wild 200 bull nettle 160 Bull Thistle 44 bur 72 Bur Cucumber 100 burdock 30 Burdock, Common 30 bur grass 220 bur-marigold 34 burr cucumber 100 burs 30 Buttercup 6 Buttercups 6 butterprint 120 C CAGSE 136 Calystegia sepium 136 Canada Fleabane 50 Canada Thistle 42 Canadian thistle 42 candlestick 88 cankerwort 70 CAPBP 142 capillary 230 Capsella bursa-pastoris 142 card thistle 208 Carduus nutans 46 carelessweed 166 carotte 18 Carpetweed 10 carrot sauvage 18 carrot weed 32 Carrot, Wild 18 Catchfly, Night-Flowering 178 catchweed bedstraw 116 CCHPA 220 Cenchrus longispinus 220 CENMA 36 Centaurea maculosa 36 Cerastium fontanum 174 CERVU 174 Chamomile, Scentless 56 charlock 150 CHEAL 92 cheat 216, 218 cheat grass 216, 218 cheat grass brome 216 cheeses 124 CHEFI 94 chénopode à feuilles de figuier 94 Chenopodium album 92 Chenopodium ficifollium 94 Chervil, Wild 14 Chess 218 WEED ID GUIDE FOR ONTARIO CROPS 251 EPPO Codes: UPPER CASE • Common Names: Title Case Latin Names: Sentence case • Other names: lower case chickenweed 62 Chickweed 184 Chickweed, Mouse-Eared 174 Chicory 40 chufa 244 CHYLE 38 Cichorium intybus 40 CICIN 40 Cicuta maculata 16 cinquefoil 196 Cinquefoil, Sulphur 196 CIRAR 42 Cirsium arvense 42 Cirsium vulgare 44 CIRVU 44 CIUMC 16 Clammy Ground-Cherry 156 cleaver 118 Cleavers 116 climbing bindweed 200 clotbur 30, 72 Cocklebur 72 Cockle, White 176 coffee-weed 40 colewort 68 common annual sow-thistle 68 Common Burdock 30 common chickweed 184 common chicory 40 common cow parsnip 20 common evening-primrose 78 Common Groundsel 62 Common Mallow 124 Common Milkweed 126 Common Mullein 88 common mustard 150 common nipplewort 54 252 common plantain 188 Common Ragweed 26 common speedwell 80 Common Speedwell 82 common waterhemp 172 Common Yellow Woodsorrel 110 compass plant 52 Composite or aster 58 CONAR 138 Convolvulus arvensis 138 Conyza canadensis 50 copperleaf 206 corn bindweed 200 Corn Speedwell 80 Corn Spurry 182 cotton thistle 58 couch grass 212 cow bell 180 Cow Parsnip 20 Crabgrass, Large 224 Crabgrass, Smooth 222 creeping sow-thistle 64 creeping thistle 42 CRUNU 46 Cucumber, Bur 100 Cucumber, Wild 98 cupped nightshade 164 curly dock 204 Cyperus esculentus 244 CYPES 244 D daisy fleabane 48 Daisy, Ox-Eye 38 Dandelion 70 DATST 154 Datura stramonium 154 WEED ID GUIDE FOR ONTARIO CROPS DAUCA 18 Daucus carota 18 deadly nightshade 162 Deadnettle, Purple 134 dent-de-lion 70 Descurainia sophia 144 DESSO 144 devil’s potato 160 devil’s tobacco 88 devil’s tomato 160 devil’s trumpet 154 DIGIS 222 Digitaria ischaemum 222 Digitaria sanguinalis 224 DIGSA 224 dioecious amaranth 166 Dipsacus fullonum 208 DIWSI 208 dock cress 54 Docks 204 Dogbane 74 dog nettle 130 Dog Strangling Vine 128 doorweed 188, 198 dooryard plantain 188 Downy Brome 216 downy chess 216 Draba verna 146 E earth almond 244 Eastern Black Nightshade 162 ECHCG 226 Echinochloa crus-galli 226 Echinocystis lobata 98 Echium vulgare 4 ECNLO 98 EHIVU 4 elephant ear 120 Elytrigia repens 212 English plantain 186 EPIAC 76 Epilobium ciliatum 76 EQUAR 104 EQUHY 106 Equisetum arvense 104 Equisetum hyemale 106 ERIAN 48 ERICA 50 Erigeron annuus 48 ERPVE 146 European bindweed 138 evening-primrose 78 Evening-Primrose, Yellow 78 eye-bright 192 F Fallopia convolvulus 200 Fall Panicum 232 fat-hen 92 Field Bindweed 138 field daisy 38 Field Horsetail 104 field mustard 150 field pansy 210 field pennycress 152 Field Peppergrass 148 field pepperweed 148 field sow-thistle 64 field thistle 42 Field Violet 210 fig-leaved goosefoot 94 Figleaved Goosefoot 94 finger grass 222, 224 WEED ID GUIDE FOR ONTARIO CROPS 253 EPPO Codes: UPPER CASE • Common Names: Title Case Latin Names: Sentence case • Other names: lower case fleabane 50 Fleabane, Annual 48 Fleabane, Canada 50 Flixweed 144 flowering nettle 130 Flower-of-an-hour 122 foot-a-night vine 112 Foxtail, Giant 238 Foxtail, Green 242 Foxtail, Yellow 240 frenchweed 152 fringed willowherb 76 G GAETE 130 GALAP 116 Galeopsis tetrahit 130 Galium aparine 116 Galium mollugo 118 GALMO 118 garden mallow 124 Garlic Mustard 140 Giant Foxtail 238 Giant Hogweed 22 Giant Ragweed 28 Goldencreeper 102 Goosefoot, Figleaved 94 goose-grass 116 Grass, Barnyard 226 great angelica 12 great ragweed 28 Green Foxtail 242 Green Pigweed 168 grimsel 62 grip grass 116 ground almond 244 ground-cherry 156, 158 254 Ground-Cherry, Clammy 156 Ground-Cherry, Smooth 158 groundsel 62 Groundsel, Common 62 gypsy-combs 208 gypsy-weed 82 H hair grass 230 hairy crabgrass 224 hairy ground-cherry 156 Hairy Nightshade 164 halberdleaf orach 90 hare’s lettuce 68 Hedge Bindweed 136 hedge morning-glory 136 hell’s bells 154 Hemp-nettle 130 Henbit 132 henbit deadnettle 132 Heracleum mantegazzianum 22 Heracleum sphondylium 20 HERMA 20 HERMZ 22 herrick 150 Hibiscus trionum 122 HIBTR 122 hogweed 22, 50 Hogweed, Giant 22 Horse-Nettle 160 horse-pipes 104 Horsetail, Field 104 horseweed 50 husk-tomato 158 I Indian celery 20 WEED ID GUIDE FOR ONTARIO CROPS Indian hemp 74 Indian mallow 120 inkweed 190 Ivy, Poison 8 J Jacobaea vulgaris 60 Japanese lantern 156, 158 Jimsonweed 154 joint grass 104 June grass 236 K kale 150 KCHSC 96 kinghead 28 knapweed 36 Knapweed, Spotted 36 knot-grass 198 Knotweed, Prostrate 198 Kochia 96 Kochia scoparia 96 Ko-hemp 112 Kudzu 112 L LACSE 52 Lactuca serriola 52 Lady’s Thumb 202 LAMAM 132 Lamb’s-quarters 92 Lamium amplexicaule 132 Lamium purpureum 134 LAMPU 134 LAPCO 54 Lapsana communis 54 Large Crabgrass 224 large morning-glory 136 large mouse ear chickweed 174 LEPCA 148 Lepidium campestre 148 lesser burdock 30 Lettuce, Prickly 52 Leucanthemum vulgare 38 lion’s-tooth 70 locoweed 154 Long-Spined Sandbur 220 lupuline 108 luzerne 108 M Mallow, Common 124 MALNE 124 Malva neglecta 124 mare’s tail 104 mare’s-tail 50 marguerite 38 mat-grass 198 MATIN 56 Medicago lupulina 108 Medick, Black 108 MEDLU 108 MELAL 176 MELNO 178 Mercury, Three-Seeded 206 Mexican fireweed 96 milk thistle 64, 68 milkweed 126 Milkweed, Common 126 millet 234, 238, 240, 242 Millet, Proso 234 mollugo 10 Mollugo verticillata 10 WEED ID GUIDE FOR ONTARIO CROPS 255 EPPO Codes: UPPER CASE • Common Names: Title Case Latin Names: Sentence case • Other names: lower case MOLVE 10 mouse-ear 174 mouse ear chickweed 174 Mouse-Eared Chickweed 174 MUHFR 228 Muhlenbergia frondosa 228 Muhly, Wire-Stemmed 228 Mullein, Common 88 musk thistle 46 musquash-root 16 mustard 150 Mustard, Garlic 140 Mustard, Wild 150 N Narrow-Leaved Plantain 186 neckweed 86 Night-Flowering Catchfly 178 Nightshade, Eastern Black 162 Nightshade, Hairy 164 nippleweed 54 Nipplewort 54 Nodding Thistle 46 northern nut-grass 244 Northern Willowherb 76 nut grass 244 Nutsedge, Yellow 244 O Oats, Wild 214 Oenothera biennis 78 OEOBI 78 old witch grass 230 Onopordum acanthium 58 ONRAC 58 Oxalis 110 Oxalis stricta 110 256 OXAST 110 Ox-Eye Daisy 38 P Palmer Amaranth 166 palmer’s pigweed 166 PANCA 230 PANDI 232 panic grass 230 panic millet 234 Panicum capillare 230 Panicum dichotomiflorum 232 Panicum, Fall 232 Panicum miliaceum 234 PANMI 234 Parsnip, Cow 20 Parsnip, Wild 24 Pastinaca sativa 24 PAVSA 24 pennycress 152 Peppergrass, Field 148 pepperweed 148 Perennial Sow-Thistle 64 perennial thistle 42 Persicaria maculosa 202 PHTAM 190 PHYHE 156 Physalis heterophylla 156 Physalis longifolia 158 PHYSU 158 Phytolacca americana 190 pick purse 142 pie-marker 120 pigeon grass 238, 240, 242 pigweed 92, 170 Pigweed, Green 168 Pigweed, Redroot 170 WEED ID GUIDE FOR ONTARIO CROPS Pimpernel, Scarlet 192 PLALA 186 PLAMA 188 Plantago lanceolata 186 Plantago major 188 plantain 188 Plantain, Broad-Leaved 188 Plantain, Narrow-Leaved 186 Poa 236 POASP 236 poison chickweed 192 Poison Ivy 8 poison parsnip 16 pokeberry 190 Pokeweed 190 POLAV 198 POLCO 200 POLPE 202 Polygonum aviculare 198 poorland flower 38 POROL 194 portulaca 194 Portulaca oleracea 194 potatoweed 164 Potentilla recta 196 poverty weed 142 powell amaranth 168 prickly annual sow-thistle 66 prickly burr 154 prickly cucumber 98 Prickly Lettuce 52 proso 234 Proso Millet 234 Prostrate Knotweed 198 PTLRC 196 PUELO 112 Pueraria montana 112 purple angelica 12 purple archangel 134 Purple Deadnettle 134 Purslane 194 Purslane Speedwell 86 pursley 194 pushki 20 pusly 194 pussley 194 Q Quackgrass 212 Queen Anne’s-Lace 18 quitch grass 212 R Ragweed, Common 26 Ragweed, Giant 28 ragwort 62 Ragwort, Tansy 60 RANAC 6 RANRE 6 Ranunculus acris 6 Ranunculus repens 6 rattleweed 180 red belevedere 96 red chickweed 192 red dead-nettle 134 red nettle 134 redroot 170 Redroot Pigweed 170 red shank 202 rhombic copperleaf 206 ribgrass 186 road-spread 198 rough pigweed 170 RUMCR 204 WEED ID GUIDE FOR ONTARIO CROPS 257 EPPO Codes: UPPER CASE • Common Names: Title Case Latin Names: Sentence case • Other names: lower case Rumex crispus 204 Rumex obtusifolius 204 RUMOB 204 Rush, Scouring 106 S sand brier 160 Sandbur, Long-Spined 220 sand burr 160 Scarlet Pimpernel 192 Scentless Chamomile 56 scentless mayweed 56 Scotch Thistle 58 Scouring Rush 106 scratch-grass 116 scutch grass 212 Senecio vulgaris 62 SENJA 60 SENVU 62 Setaria faberi 238 Setaria pumila 240 Setaria viridis 242 SETFA 238 SETLU 240 SETVI 242 shepherd’s clock 192 shepherd’s heart 142 Shepherd’s-Purse 142 short ragweed 26 Sicyos angulatus 100 Silene latifolia 176 Silene noctiflora 178 Silene vulgaris 180 silkweed 126 SILVU 180 simson 62 Sinapis arvensis 150 258 SINAR 150 SIYAN 100 slender chess 216 small crab grass 222 small-flowered morning glory 138 small-flowered thistle 42 smartweed 202 Smooth Bedstraw 118 Smooth Crabgrass 222 Smooth Ground-Cherry 158 smooth panicum 232 smooth witch grass 232 snake grass 106 Solanum carolinense 160 Solanum physalifolium 164 Solanum ptychanthum 162 SOLCA 160 SOLPT 162 SOLSA 164 SONAR 64 SONAS 66 Sonchus arvensis 64 Sonchus asper 66 Sonchus oleraceus 68 SONOL 68 sour clover 110 sour grass 110 sow-thistle 64 Sow-Thistle, Annual 68 Sow-Thistle, Perennial 64 Sow-Thistle, Spiny Annual 66 spear thistle 44 speedwell 80, 82 Speedwell, Common 82 Speedwell, Corn 80 Speedwell, Purslane 86 Spergula arvensis 182 WEED ID GUIDE FOR ONTARIO CROPS Spiny Annual Sow-Thistle 66 spotted hemlock 16 Spotted Knapweed 36 Spotted Water-Hemlock 16 SPRAR 182 Spreading Atriplex 90 spreading dogbane 74 spreading panic grass 232 spring cleavers 116 spring whitlowgrass 146 spurrey 182 Spurry, Corn 182 star cucumber 100 star thistle 36 Stellaria media 184 STEME 184 sticky cockle 178 stinking willie 60 stinkweed 154 Stinkweed 152 stinky mustard 140 Sulphur Cinquefoil 196 summer-cypress 96 summer grass 226, 236 swallow-wort 128 T Tall Beggarticks 34 tall pigweed 170 tall ragweed 28 tansy mustard 144 Tansy Ragwort 60 Taraxacum officinale 70 TAROF 70 Teasel 208 THDDU 102 Thistle, Bull 44 Thistle, Canada 42 Thistle, Nodding 46 Thistle, Scotch 58 Thladiantha dubia 102 thladianthe 102 THLAR 152 Thlaspi arvense 152 thornapple 154 Three-Seeded Mercury 206 tickle grass 230 Toxicodendron radicans 8 TOXRA 8 Tripleurospermum inodorum 56 Tufted Vetch 114 tumble grass 230 tumbleweed 224 twitch 212 twitch grass 212 V Velvetleaf 120 Venice mallow 122 VERAR 80 Verbascum thapsus 88 VEROF 82 Veronica arvensis 80 Veronica officinalis 82 Veronica peregrina 84, 86 VERPE 84 VERPG 86 VESTH 88 Vetch, Tufted 114 VICCR 114 Vicia cracca 114 Vincetoxicum rossicum 128 Vine, Dog Strangling 128 vine-that-ate-the-South 112 WEED ID GUIDE FOR ONTARIO CROPS 259 EPPO Codes: UPPER CASE • Common Names: Title Case Latin Names: Sentence case • Other names: lower case VIOAR 210 Viola arvensis 210 Violet, Field 210 viper’s bugloss 4 VNCRO 128 W water grass 226 water hemlock 16 Water-Hemlock, Spotted 16 Waterhemp 172 white bedstraw 118 white campion 176 White Cockle 176 white daisy 38 white goosefoot 92 white pigweed 92 white thistle 58 whiteweed 38 Whitlowgrass 146 Wild Buckwheat 200 wild burdock 30 Wild Carrot 18 Wild Chervil 14 Wild Cucumber 98 wild lettuce 52 wild madder 118 wild millet 238, 240, 242 wild morning glory 138 wild morning-glory 136 Wild Mustard 150 Wild Oats 214 wild pansy 210 Wild Parsnip 24 wild portulaca 194 wild rhubarb 30 wild teasel 208 260 wild tomato 160 Willowherb, Northern 76 Wire-Stemmed Muhly 228 Witchgrass 230 woodsorrel 110 Woodsorrel, Common Yellow 110 Wormwood, Biennial 32 X XANST 72 Xanthium strumarium 72 Y yellow cinquefoil 196 yellow clover 108 Yellow Evening-Primrose 78 Yellow Foxtail 240 yellow mustard 150 yellow nut-grass 244 Yellow Nutsedge 244 yellow parsnip 24 yellow woodsorrel 110 WEED ID GUIDE FOR ONTARIO CROPS What is a weed? “a plant whose virtue has not yet been discovered” — Ralph Waldo Emerson (1878) “a plant out of place, or growing where it is not wanted “ — W.S. Blatchley (1912) “useless, unwanted, undesirable” — L. H. Bailey and E.Z. Bailey (1941) “a plant growing where it is not desired” — K.P. Buchholtz (1967) “It makes me feel the way I need to feel.” — Snoop Dogg (2008) Weed ID Guide for Ontario Crops © 2016 Cowbrough, Tardif, and Letarte Common Mullein (Figwort or Snapdragon) Scrophulariaceae family Verbascum thapsus
