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DESCRIPTION: Exotic bush honeysuckles are native of Eurasia. The
plants are upright, generally deciduous shrubs that range from 6 to 15 feet
in height. The 1-2 ½ inch, egg-shaped leaves are opposite along the stem
and short-stalked. Pairs of fragrant, tubular flowers less than an inch long
are borne along the stem in the leaf axils. Flower color varies from creamy
white to pink or crimson in some varieties of Tartarian honeysuckle. The
fruits are red to orange, many-seeded berries. Unlike the exotics, most of
our native bush honeysuckles have solid stems.
CURRENT MANAGEMENT APPROACHES: Mechanical and chemical
methods are the primary means of control of exotic bush honeysuckles. No
biological control agents are currently available for these plants Hand
removal of seedlings or small plants may be useful for light infestations.
Seedlings of exotic bush honeysuckles can also be controlled by application
of a systemic herbicide. Prescribed burning has shown some promise for
exotic bush honeysuckles growing in open habitats. In all instances, control
should be initiated prior to the seed dispersal period (late summer to early
autumn) to minimize reinvasion of treated habitats.
HABITAT IN THE UNITED STATES:
Exotic bush honeysuckles are relatively shade-intolerant and most often occur in forest
edge, abandoned field, pasture, roadsides and other open, upland habitats. Woodlands,
especially those that have been grazed or otherwise disturbed may also be invaded by
exotic bush honeysuckles.
ECOLOGICAL THREAT: Exotic bush honeysuckles can rapidly invade and overtake a
site, forming a dense shrub layer that crowds and shades out native plant species. They
alter habitats by decreasing light availability, by depleting soil moisture and nutrients, and
possibly by releasing toxic chemicals that prevent other plant species from growing in the
vicinity. Exotic bush honeysuckles may compete with native bush honeysuckles for
pollinators, resulting in reduced seed set for native species. In addition, the fruits of exotic
bush honeysuckles do not offer migrating birds the high-fat, nutrient-rich food sources
needed for long flights, that are supplied by native plant species.
Description: Bull thistle is a biennial, and sometimes annual or monocarpic perennial,
forb. In the juvenile phase, individual bull thistle plants form a single rosette with a taproot
up to 28 inches (70 cm) long. Rosettes may develop up to 3.3 feet (1 m) in diameter.
The taproot does not spread, but develops several smaller lateral roots. Stems have spiny
wings and grow 1 to 6.6 feet (0.3 to 2 m) tall, with many spreading branches, and
sometimes a single stem. Bull thistle stem leaves are more or less lance-shaped and 3 to
12 inches (7.6-30 cm) long, prickly hairy on the top and very hairy underneath. Lobes on
leaves are tipped with stout spines. Bull thistle flowerheads are 1.5 to 2 inches (3.8 to 5
cm) in diameter, 1 to 2 inches (2.5-5 cm) long, usually solitary, and more or less clustered
at the ends of shoots and branches. Flowers are subtended by narrow, spine-tipped
bracts. Bull thistle fruits are achenes, 1/16th-inch (0.15 cm) long, with a long, hairy plume
that is easily detached.
Control and Management:
Biological: The seed-feeding fly, Urophora stylata Fabricius, has been
selected and released for biological control of bull thistle.
Mechanical: Mow to prevent seeding.
Chemical: Pre-emerge with Aatrex 4L, Oust, Princep Liquid. Post-emerge with 2,4-D +
dicamba, Garlon 3A, Garlon 4, Roundup/Accord, and Stinger
Habitat: Bull thistle is a very widespread weed that can grow in a wide range of
environments but is most troublesome in recently or repeatedly disturbed areas such as
pastures, overgrazed rangelands, recently burned forests and forest clearcuts, and
along roads, ditches, and fences. Bull thistle is found on dry and wet soils, but is most
common on soils with intermediate moisture.
Ecological Damage: Although bull thistle is a problem predominantly in disturbed
areas, it also can be found in natural areas. The basal rosette may grow to nearly 1
m in diameter before bolting, and, once established, bull thistle out-competes native
plant species for space, water, and nutrients.
DESCRIPTION: Common buckthorn is a shrub or small tree in the buckthorn
family (Rhamnaceae) that can grow to 22 feet in height with a 10-inch wide
trunk. The crown shape of mature plants is spreading and irregular. The grey
to brown bark is rough textured when mature and may be confused with that
of plum trees. The inner bark is yellow and the heartwood is pink to orange.
Twigs are often tipped with a spine. In spring, dense clusters of 2 to 6,
yellow-green, 4-petaled flowers emerge from stems near the bases of leaf
stalks. Small black fruits about 1/4 inch in cross-section and containing 3 -4
seeds, form in the fall. Leaves are broadly oval, rounded or pointed at the tip,
with 3-4 pairs of up curved veins, and have jagged, toothed margins. Leaves
appear dark, glossy green on the upper surface and stay green late into fall,
after most other deciduous leaves have fallen.
CURRENT MANAGEMENT APPROACHES: This plant is listed as an
nvasive and noxious weed by the U. S. federal government. Mechanical,
physical and chemical methods are used to control common buckthorn and
glossy buckthorn (Rhamnus frangula), also an invasive exotic plant.
Prescribed fire is another method proposed for controlling buckthorn
seedlings in fire-adapted natural areas. Careful application of herbicides
such as, triclopyr herbicide effectively controls common buckthorn.
HABITAT IN THE UNITED STATES: Common buckthorn prefers lightly shaded
conditions. An invader mainly of open oak woods, deadfall openings in woodlands, and
woods edges, it may also be found in prairies and open fields. It is tolerant of many soil
types, well drained sand, clay, poorly drained calcareous, neutral or alkaline, wet or dry.
ECOLOGICAL THREAT: Exotic buckthorns tend to form dense, even-aged thickets,
crowding and shading out native shrubs and herbs, often completely eradicating them.
Dense buckthorn seedlings prevent native tree and shrub regeneration. In fire-adapted
ecosystems such as savannas and prairies, the lack of vegetation under buckthorn
prohibits fires. Buckthorn control is also of interest to small grain producers; the shrub is
an alternate host of the crown rust of oats, which affects oat yield and quality.
DESCRIPTION: a perennial vine that climbs by twisting its stems around vertical structures, including
limbs and trunks of shrubs and small trees. Leaves are oblong to oval, sometimes lobed, have short
stalks, and occur in pairs along the stem. Flowers are tubular, with five fused petals, white to pink,
turning yellow with age, very fragrant, and occur in pairs along the stem at leaf junctures. Stems and
leaves are sometimes covered with fine, soft hairs. Small black fruits are produced in autumn, each
containing 2-3 oval to oblong, dark brown seeds about 1/4 inch across.
MANAGEMENT OPTIONS:
Manual and mechanical- For small patches, hand-pull seedlings and young plants when the soil is
moist, holding low on the stem to remove the whole plant along with its roots. Monitor frequently and
remove any new plants. For large patches, repeated mowing combined with herbicide application is
effective. Burning removes above ground vegetation but does not kill the underground rhizomes,
which will continue to sprout. In certain situations, tethered goats have been used to remove
honeysuckle growth, but must be monitored to prevent their escape to the wild where they would
become an added ecological threat. Chemical- For effective control with herbicides, healthy green
leaves must be present at application time and temperatures must be sufficient for plant activity.
Several systemic herbicides (e.g., glyphosate and triclopyr) move through the plant to the roots when
applied to the leaves or stems and have been effective on Japanese honeysuckle. Treatment in the
fall, when many non-target plants are going dormant, is best. Biological control- No biological control
agents are currently available for Japanese honeysuckle.
HABITAT & DISTRIBUTION IN THE UNITED STATES: It thrives in a wide variety of habitats including
fields, forests, wetlands, barrens, and all types of disturbed lands.
ECOLOGICAL THREAT: In North America, Japanese
honeysuckle has few natural enemies allowing it to spread widely
and out-compete native plant species. Its evergreen to
semievergreen nature gives it an added advantage over native
species in many areas. Shrubs and young trees can be killed by
girdling when vines twist tightly around stems and trunks, cutting
off the flow of water through the plant. Dense growths of
honeysuckle covering vegetation can gradually kill plants by
blocking sunlight from reaching their leaves. Vigorous root
competition also helps Japanese honeysuckle spread and
displace neighboring native vegetation.
DESCRIPTION: Purple loosestrife is an erect perennial herb in the loosestrife family (Lythraceae), with
a square, woody stem and opposite or whorled leaves. Leaves are lance-shaped, stalkless, and heartshaped or rounded at the base. Plants are usually covered by a downy pubescence. Loosestrife plants
grow from four to ten feet high, depending upon conditions, and produce a showy display of magentacolored flower spikes throughout the summer (June to September). Flowers have five to seven petals.
Mature plants can have from 30 to 50 stems that are capable of producing an estimated two to three
million seeds per year from a single rootstock. It spreads through the vast number of seeds dispersed
by wind and water, and vegetatively through underground stems at a rate of about one foot per year.
CONTROL AND MANAGEMENT: Manual- Small infestations of young purple loosestrife
plants may be pulled by hand, preferably before seed set.
Chemical- For older plants, spot treating with a glyphosate type herbicide (e.g., Rodeo for
wetlands, Roundup for uplands) is recommended. These herbicides may be most effective
when applied late in the season when plants are preparing for dormancy. However, it may be
best to do a mid-summer and a late season treatment, to reduce the amount of seed
produced.
Biological control - For long term control of large infestations biological control is
recommended. As of 1997, three insect species from Europe have been approved by the USDA
for use as biological control agents. These plant-eating insects include a root-mining weevil
(Hylobius transversovittatus), and two leaf-feeding beetles (Galerucella calmariensis and
Galerucella pusilla). Two flower-feeding beetles (Nanophyes) that feed on various parts of
purple loosestrife plants are still under investigation. Galerucella and Hylobius have been
released experimentally in natural areas in 16 northern states, from Oregon to New York.
Although these beetles have been observed occasionally feed
HABITAT IN THE UNITED STATES: Purple loosestrife is capable of invading wetlands such as
freshwater wet meadows, tidal and non-tidal marshes, river and stream banks, pond edges, reservoirs,
and ditches.
ECOLOGICAL THREAT: Purple loosestrife adapts to natural and disturbed wetlands. As it establishes
and expands, it can outcompete and replace native grasses, sedges, and other flowering plants that
provide a higher quality source of nutrition for wildlife. The highly invasive nature of purple loosestrife
allows it to form dense, homogeneous stands that restrict native wetland plant species, including some
federally endangered orchids, and reduce habitat for waterfowl.
DESCRIPTION: Yellow starthistle is an annual herbaceous plant in the aster family (Asteraceae).
Plants are gray-green to blue-green, grow from 6 in. to 5 ft. (15 cm to 15 dm) in height, and have
deep taproots. Flowers are bright yellow with sharp spines surrounding the base, giving the plant a
particularly menacing appearance and a painful response if touched. Stems and leaves are
covered with cottony wool. Basal leaves are 2 to 3 in. (6 – 7 cm.) long and deeply lobed. Upper
leaves are short (0.5 to 1.0 in.; 1 to 2.5 cm) and narrow, with few lobes.
CURRENT MANAGEMENT APPROACHES: When driving, walking, or moving livestock
through infested areas, clothing, vehicles, and animals should be inspected and cleaned to
remove any seeds before continuing on into uninfested areas.
Biological Control: Six biological control insects have been released in the United States
for control: Bangasternus orientalis, Eustenopus villosus, Urophora jaculata, Urophora sirunaseva,
Larinus curtus, and Chaetorellia australis. Of these, five became established and three (B. orientalis,
U. sirunaseva and E. villosus) are widespread. Also, the accidentally introduced fly, Chaetorellia
succinea has a strong affinity to yellow starthistle and is found almost everywhere yellow starthistle
occurs. All of these insects attack the seed head of yellow starthistle, effectively limiting the number
of seeds the plants are able to produce. Current research indicates that the insects have reduced
seed yield by at least 50%. The rust fungus, Puccinia juncea var. solstitialis was released in
California in 2003. It is too early to know if this rust will establish and eventually cause high mortality
of yellow starthistle in the wild. Several more fungi and insects are currently being tested for
introduction into the United States.
Chemical Control: Application of the systemic herbicides clopyralid or picloram between December
and April seems to be the most effective. Application during the winter encourages the growth of
other, more desirable, plants.
Mechanical Control: Mowing is effective during the early flowering stage or when most buds have
produced spines. However, it is only successful when no leaves are present below the level of the
cut.
Grazing: Sheep, goats, and cattle graze on yellow starthistle in early spring, before the flower’s
spines develop.
HABITAT: Plants typically thrive in full sunlight and deep, well-drained soils, where annual rainfall
is between 10-60 inches, and is especially common in disturbed areas such as roadsides. It
chokes out the native plants, reducing biodiversity, and wildlife habitat and forage. Yellow
starthistle is a strong invader that occurs in forty-one of the United States. It is most concentrated
in California.
BIOLOGY & SPREAD: Spread of yellow starthistle is by seed and each seed head can produce
from 35 to approximately 80 seeds. However, the seeds have no wind-dispersal mechanisms so few
seeds move more than two feet from the parent plant without assistance.