Download Forest Seed Pest

Forest seed pest
2009-TPFQ-33
Agenda Item: 8
Forest Seed Pest
Seed Fungi
fonte: http://www.forestpests.org/nursery/seedfungi.html
Cordell C.E., Anderson R.L., Hoffard W.H., Landis T.D., Smith R.S. Jr., Toko H.V., 1989. Forest
Nursery Pests. USDA Forest Service, Agriculture Handbook No. 680, 184 pp.
Hosts
Seed fungi, especially species of Aspergillus, Diplodia, Penicillium, Fusarium, Pestalotia,
Trichoderma, and a number of Phycomycetes, affect the seed of all forest tree species.
Distribution
Seed fungi are found throughout the known ranges of all tree species. Some species of fungi,
such as the pitch canker fungus, Fusarium subglutinans (syn. F. moniliforme var. subglutinans),
appear to be confined to certain pine species, and the amount of damage they cause varies with
geographic location.
Damage
The losses caused by seed fungi may occur during seed development, storage, or
germination. Damage results from loss of seed viability or from seedling infection following
germination. In general, however, losses associated with these fungi are low.
Diagnosis
Seed fungi are found on and in the seedcoat and in the gametophyte and embryo. With some
exceptions, such as molds, these fungi cannot be detected by examining the outside of seeds. Some
internal seed fungi can be detected by the visible presence of mycelium when the seed is cut open.
However, the only accurate way to assess the incidence of seed fungi is to place samples of the
seeds on appropriate culture media. After incubation, fungi can be detected by the presence of
fruiting bodies or mycelium on the surface of the seed and the growth medium. Because of the
large number of fungi that infect seed, a specialist is usually needed to identify them.
On conifers in the nursery, damage from pathogenic seed fungi often can be detected by the
presence of superficial mycelium on infected tissues of cotyledons where the seedcoat is still
attached .
Biology
A variety of fungi are found in association with the seeds of forest trees. Not all are
pathogenic
Some of these fungi, such as species of Diplodia and Fusarium, are pathogenic and may
retard seed germination or cause damping-off, root rot, or other diseases of seedlings.
Research has not pinpointed the mode of entry of internal seed fungi. They may enter during
seed and cone development or through cracks in the seedcoat, especially after the seed has been
extracted from the cone. External fungi could develop on the seed at any time after the seedcoat is
formed.
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The types and amounts of seed fungi vary with the tree species, location, and year of
collection.
Fungus populations may increase during all phases of seed development and processing. It
has been shown that seed collected from F. subglutinans-infected orchards frequently carries the
same fungus. Seed-harvesting practices such as letting the seed fall on nets or the ground before
harvesting seem to increase the incidence of seed fungi. Cone-processing procedures that result in
high moisture and temperature conditions in the cone often increase seed fungi. Handling seeds
during extraction can also attached.
Control
Prevention - Identify seed orchards that have seedlots with internal seed fungi. When possible,
avoid using seedlots that are known to be infected with seed-borne pathogens. Identify seedlots that
have a high occurrence of pathogenic fungi in unsound seeds and remove the unsound seeds. Avoid
shipping seeds containing pathogenic fungi.
Cultural - To detect possible disease development, monitor seedlots in a nursery known to contain
pathogenic fungi.
Seed Treatment - Several different types of direct seed treatment are available and have been used
on certain tree species.
Surface drying of several species of conifer seed has been effective in reducing some surface
fungi.
A 48-hour running water rinse reduces fungal and bacterial contamination on the seed of
some pine species.
Sterilization with laundry bleach reduces fungi on most tree seed. In general, these
chemicals work better on the seeds with thicker coats; seeds with thin seed coats are more easily
damaged.
Captan, thiram, and benomyl have been reported to reduce seed fungi, but fungicide
treatments are often selective in that they only affect one or two fungi and may reduce germination.
Selected References
Anderson, Robert L. 1986. Checklist of micro-organisms associated with tree seeds in the world,
1985. Gen. Tech. Rep. SE-39. Asheville, NC: U.S. Department of Agriculture. Forest Service.
Southeast Forest Experiment Station. 34 p.
Miller, Thomas; Bramlett, D.L. 1979.Damage to reproductive structures of slash pine by two seedborne pathogens: Diplodia gossypina and Fusarium moniliforme var. sublglutinans. In: Bonner,
frank, ed. Proceedings: flowering and seed development of trees: a symposium; 1978 May 5-6:
Starkville. MS. New Orleans, L.A: U.S. Department of Agriculture, Forest Service, Southern Forest
Experiment Station: 347-355.
Sutherland, Jack H.; Miller, Thomas; Quinard, Rodolfo Salinas, eds. 1987. Cone and seed diseases
of North American conifers. Publ. 1. Victoria. BC: North American Forestry Commission. 77 p.
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Os gêneros de fungo mais comumente relatados são Aspergillus, Curvularia, Fusarium,
Mucor, Rhizopus e Trichoderma.
Insects
Fonte: http://en.sl.life.ku.dk/upload/chapter7_001.pdf
The diversity of insect species is vast and far exceeds that of plant species. Yet the number
of known seed-feeding insect species is small. Taxonomically related plant species often share the
same type of insect pests, e.g. bruchids on legumes, Megastigmus on conifers, but many insect
families and genera infest seeds of plants belonging to very different plant families. The majority of
seed pests belong to the following five orders.
Coleoptera (Beetles)
Beetles have hard leathery fore wings (elytra) and membraneous hind wings used for flight
and folded under the elytra when resting. Larvae have a distinct head capsule and usually thoracic
legs. Both adult and larva have chewing mouth parts. The pupa resembles the adult. Important
families are:
-Bruchidae (bruchids) with 56 genera of which the most common are Brunchus, Brunchidius,
Tuberculobruchus, Conicobruchus, Caryedon, Callosobruchus, Acenthoscelides. Bruchids are the
prevalent pest in Leguminosae such as Acacia, Prosopis, Albizia, Brachystegia, Dalbergia spp., but
are also found in e.g. Cordia alliodora, some Eucalyptus spp. and palms. Species of the subfamily
Pachymerinae feed almost exclusively on palm seeds in America (Johnson et al. 1995). Bruchid
species have been found in 32 plant families (Johnson 1983).
-Curculionidae (weevils and snout beetles). An important genus is Nanophyes, which occurs
throughout the tropics infesting e.g. Terminalia ivorensis in West Africa and dipterocarps in
Malaysia (ref. see above). Alcidodes dipterocarpi attack Shorea spp. in Thailand (Eungwijarnpanya
and Hedlin 1984), and Apion spp. feed on Triplochiton scleroxylon. Scolytidae (bark beetles). The
most common genus is Conophteorus, which causes vast destruction of North American pine cones
(Hedlin et al. 1981).
-Hemiptera (Plant bugs) True bugs have leathery fore wings with membraneous tips; hind wings
membraneous and shorter than fore wings. The wings lie flat over the abdomen. The mouthparts
consist of a bundle of needle-like stylets within a segmented sheath which forms a beak or
proboscis. During feeding the bug inserts its proboscis into the food material; salivary fluid
dissolves the food which is then sucked up through the duct of the proboscis. Metamorphosis is
gradual with the immature forms of nymphs resembling the adult in form and feeding habit.
Dysdercus spp. attack mainly species of the plant order Malvales (Sterculiaceae, Malvaceae,
Bombacaceae, Tiliaceae). Zulubius acaciaphagus causes heavy attack on Acacia cyclops in S. Africa
(Holmes and Rebelo 1988).
-Lepidoptera (Moths and butterflies)
Adults with four membraneous wings almost wholly covered with minute overlapping scales.
Mouthparts of most species consist of a long tube-like structure, coiled up when not in use. Adults
usually feeding on flower nectar are important pollinators. Antennae are thread or feather like.
Larvae (caterpillars) are usually cylindrical with three pairs of thoracic legs and up to five pairs of
abdominal legs. Well developed heads with chewing mouthparts. Larvae produce silk cocoons.
Pupae are compact with appendages fused to the body.
Important families are:
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-Olethreutidae. This family of moths includes a large number of cone predators. Species of the
genera Barbara, Eucosma, and Laspeyresia cause great damage to conifers in North and Central
America (Hedlin et al. 1981). Ofatulena spp. feed on Prosopis flowers and fruits. Cryptophlebia
carpophagoides is a South American species that attacks the pods and causes heavy loss in
leguminous species like Enterolobium contortisiliquum in Argentina and Prosopis tamarugo and P.
juliflora in Chile (Kock and Campos 1978, quoted in Johnson 1983). Leptotes trigemmatus feeds on
P. tamarugo in Chile.
-Paralidae. The main genus attacking conifers is Dioryctria (cone- worms), which infest cones and
seeds as well as flowers and young shoots. It occurs both in the temperate and tropical region.
Dichocrocis punctiferalis infests seed of Tectona grandis in Thailand (Eungwijarn- panya and
Hedlin 1984). Agathiphaga is a moth that infests cones and seeds of Agathis spp. (Willan 1991).
-Diptera (Flies)
Adults have a single pair of membraneous front wings, hind wings are reduced. Mouthparts are
modified for piercing and sponging. The larva is legless and its head retracted into the thorax.
Important families with members causing cone destruction in North American conifers are
Cecidomyiidae, Anthomyiidae and Lonchaeidae (Hedlin et al. 1981).
-Hymenoptera (Wasps, sawflies and seed chalcids)
Adults have four membraneous wings, the hind wings being distinctly smaller than the forewings.
Wing venation is sparse. Mouthparts of the chewing type. Larvae differ: head capsules and legs are
present in some families, absent in others. Pupa, frequently encased in a co- coon, resembles the
adult. A single genus Megastigmus in the family Torymidae comprises a number of seed pests.
Megastigmus species are quite specialized with regard to host species, method of attack and feeding
habit (Hedlin et al. 1981). They are common seed pests of conifers and also occur in e.g. Eucalyptus
spp. (Eldridge et al. 1994) and Sesbania grandiflora (Eungwijarnpanya and Hedlin 1984). The
female insect has a long ovipositor (egg laying organ) by which it penetrates the fruit and seed-coat
to lay its eggs within the developing seed. The number of eggs varies from one to several per seed.
The larvae feed inside the developing seed and pupation takes place within the seed. Infestation can
thus not normally be recognized on the outside of the seed. The adult insect emerges via a round
exit hole, which it chews through the seed-coat and sometimes through the fruit as well.
fonte: http://www.bugwood.org/pestcontrol/insects.html
Insects in Seed Orchards and Forest Nurseries
High value, intensively managed sites, such as seed orchards and forest nurseries, require
aggressive forest insect control programs. A number of insects that are normally not considered
economic forest pests can be quite damaging in seed orchards and forest nurseries. Pheromone traps
are often used to monitor insect populations in these sites. Some of the major seed and cone insect
pests are the southern pine coneworms, pine seedbugs, various sawflies and thrips.
Coneworms
Several species of coneworms (Dioryctria spp.) are highly injurious to seeds and cones of
conifers (Figures 37-38). These insects infest all commercially significant pines as well as spruce,
fir, hemlock, and cypress. The southern pine coneworm (D. amatella) infests cones, male flowers,
shoots, and fusiform rust cankers on a variety of southern pines. Adults have a wingspan of about 1
and 1/8 inches. The forewing is dark brown with contrasting white patches in zigzag lines running
across the wings. Mature larvae are brownish to purplish above, pale whitish to greenish below and
about one inch long. This species is frequently reported to cause heavy cone losses to southern
pines.
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The Heteroptera, the true bugs, contains two families that are significant pests of a number
of conifer species. The coreid bugs (Coreidae) and the stink bugs (Pentatomidae) feed on the ovules
and seeds of pines and conifers.
Leaffooted Bugs
Leaffooted bugs in the family Coreidae genus Leptoglossus are important pests of loblolly
and shortleaf pines (Figure 39). Both the nymphs and adults are reddish-brown to gray and have
long legs with a laterally expanded “leaflike” tibia on the hind leg. The adults are 2/3 - ¾ inches in
length and have distinctive whitish marks across the wings.
There are several generations produced each year. Nymphs and adults have piercing-sucking
mouthparts that they insert into the conelets or cones to penetrate and feed upon the developing
ovules and seeds. Attacked cones show no external damage symptoms, but damage to seed can be
severe.
Stink Bugs
Stink bugs in the family Pentatomidae emit a disagreeable odor when they are disturbed.
The shieldbacked pine seed bug, Tetyra bipunctate (Herrich-Schaffer), is an important pest in
southern pine seed orchards. The adults and nymphs are oval and have a humpbacked appearance.
The adults are about 2/3 inch in length and are gray-brown to reddish-brown in color. There is only
one generation per year. Nymphs and adults both have piercing-sucking mouthparts which they
insert into cones to penetrate the seeds (Figure 40). Most of the damage occurs in late summer and
fall, which results in poor seed viability and low yields of sound seeds.
A number of insecticides are specifically labeled for and are used in seed orchards and forest
nurseries. Ground-based hydraulic sprayers, airblast sprayers (mistblowers), and handheld
compressed-air sprayers can be used to apply pesticides. Aerial applications are made with both
helicopter and fixed-wing aircraft, equipped with either conventional or by ultra-low volume
equipment.
Spruce cone maggot (Strobilomyia neanthracina)
http://www.srd.gov.ab.ca/forests/health/seedandconepests/spruceconemaggot.asp
(Written by Dr. Herb Cerezke)
Last Review/Updated: January 6, 2003
The spruce cone maggot (Strobilomyia neanthracina Michelsen) is a major pest of spruce
cones and seeds. Its larvae tunnel within cones, feeding at the base of scales and consuming seeds.
Primary Hosts and Distribution
* White spruce (Picea glauca (Moench) Voss))
* Engelmann spruce (P. engelmannii Parry)
The spruce cone maggot occurs throughout the range of white and Engelmann spruces in
Alberta.
Life Cycle
The spruce cone maggot has a one-year life cycle, but a variable portion of the
overwintering population may diapause for an additional year or more.
Larvae
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Larvae appear within the young female conelet shortly after pollination. There are three
larval instars, the first instar develops within the egg while the second and third instars construct
spiral feeding tunnels around the central cone axis. Feeding occurs from about mid-May to midJuly, after which the mature larvae tunnel out of the cone and drop to the ground. Mature larvae are
5-7 mm long, creamy white and without a definite head capsule.
Puparium
This stage develops in the soil under the tree, is reddish-brown in color, ovoid in shape, and
measures 4-6 mm by 1.2-1.4 mm. It overwinters in the soil and may undergo extended diapause for
one or more years.
Adults
These are small black flies, 3.9 - 4.6 mm long, and resemble houseflies. They are present in
the spring about the time conelets are open for pollination.
Eggs
Eggs are deposited singly between scales of conelets during or shortly after pollination.
They are pearly white, ovoid in shape and measure 1.6 x 0.5 mm.
Detection and Damage
Look for the following signs and symptoms:
* white pearly eggs deposited between scales in May;
* in bisected cones after mid-summer, note presence of holes infiltrated with resin and destroyed
seeds;
* look for a small hole ringed with brown discoloration on the exterior of the cone after mid-July.
Cones with a single larva present may have 55-65% of the filled seeds consumed, while the
presence of two or more larvae may destroy 100% of the seeds per cone. Percentage of cones
infested from year to year varies widely but may sometimes exceed 80%. Seed losses tend to be
higher in established seed orchards than in natural wild stands.
Management
* A sequential sampling method has been developed and field-tested to classify spruce cone
maggot infestation levels in white spruce seed orchards and to predict expected levels of seed loss
in the fall. The method is applied in the spring by sampling young conelets and can serve as a basis
for decisions on control strategies.
* Sampling of mature cones in the fall can serve to estimate and verify infestation levels and
percentage seed losses.
* Systemic insecticides applied as a foliar spray and as tree implants or as stem injections can be
effective in reducing populations in seed orchards.
* By observing and monitoring annual cone crop size and cone maggot infestation levels, years
of maximum seed yield can often be predicted.
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Spruce seed moth (Cydia strobilella)
fonte: http://www.srd.gov.ab.ca/forests/health/seedandconepests/spruceseedmoth.aspx
(Written by Dr. Herb Cerezke)
Last Review/Updated: January 6, 2003
Larvae of the spruce seed moth (Cydia strobilella (L.)) feed within the cones of spruces,
sometimes causing serious losses of the seed crop.
Primary Hosts and Distribution
* White spruce (Picea glauca (Moench) Voss)
* Engelmann spruce (P. engelmannii Parry)
* Black spruce (P. mariana (Mill.) B.S.P.)
The spruce seed moth occurs throughout Alberta, attacking cones in wild stands and in
established seed orchards.
Life Cycle
The spruce seed moth has a one-year life cycle, but a variable portion of the larval
population can undergo extended diapause for up to three years.
Larvae
Larvae are creamy white with a brown head capsule and measure about 10 mm long when
mature. Larvae first appear in female conelets shortly after pollination, develop through four instars
during the summer, and mature in late summer when they excavate a tunnel in the central cone axis
to overwinter.
Pupae
This stage develops in the central cone axis in spring and is light to dark brown in color and
about 5 mm long.
Adult Moths
Moths are a smoky brown color with silvery crossbands on the forewings and a wingspan of
8 - 11 mm. They appear in May about the time of pollination.
Eggs
Eggs are pale to dark orange, spherical, about 0.5 mm in diameter, and are deposited
between cone scales during or shortly after cone pollination.
Detection and Damage
* Male moths can be captured in sticky pheromone-baited traps in May;
* Infested cones have no external signs or symptoms of larvae being present;
* Cones bissected lengthwise in late summer show larvae in tunnels within the central cone axis;
* In infested cones, seeds may be partially or completely consumed and fused to the scale and
with silken tunnels between seed pairs
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Percentage of cones infested in a cone crop is variable from year to year and in different
locations, but can be as high as 70% of cones. Each larva destroys about 30% of the filled seeds per
cone.
Management
* Presence of moth populations can be monitored with pheromone-baited sticky traps. Numbers
of male moths caught may indicate the relative abundance of this insect in seed orchards.
* Sampling of young conelets after pollination can serve to detect the presence of eggs and young
larvae and form the basis for predicting infestation levels later in the season.
* Dissection of cones can be undertaken to monitor for larvae, pupae, and for estimation of
percentage seed loss.
* Because larvae overwinter within cones, the removal of mature cones from the seed orchard in
the fall also removes the resident population.
*Application of systemic insecticides to foliage, soil, as stem injections and as stem implants
are effective for reducing populations in seed orchards.
Spruce cone rust (Chrysomyxa pirolata)
fonte: http://www.srd.gov.ab.ca/forests/health/seedandconepests/spruceconerust.aspx
(Written by Dr. Herb Cerezke)
Last Review/Updated: January 6, 2003
Spruce cone rust caused by the rust fungus, Chrysomyxa pirolata Wint., periodically
damages cones of spruces in localized forest areas and can be a serious problem in spruce seed
orchards. Infection in cones seriously reduces seed yield.
Primary Hosts andDistribution
* White spruce (Picea glauca (Moench) Voss)
* Engelmann spruce (P. engelmannii Parry)
* Black spruce (P. mariana (Mill.) B.S.P.)
* Blue spruce (P. pungens Engelm.) (occassionally)
Spruce cone infections can occur throughout Alberta, but are generally heaviest along the
east slopes of the Rocky Mountains. Spruce species are the primary hosts of this fungus but the
disease also requires the presence of non-conifer host plants to complete its life cycle.
Disease Cycle
Spruce cone rust infects only the cones of spruces and will not infect the needles. Required
alternate host plants for completion of the rust life cycle include wintergreen species such as Pyrola
spp. and Moneses spp. Its development is annual and systemic or partially systemic in spruce cones
and perennial and systemic in its alternate host plants.
Infection Cycle
In spring and early summer, about the time of cone pollination, basiospores produced on
alternate host plant leaves become wind-disseminated and infect young female conelets.
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Development of pycnia on the conelets follows shortly after, and by mid- to late-summer infected
cones turn light brown, dry, and open prematurely releasing masses of yellow-orange powdery
spores (aeciospores). All spore types of this rust disease require microscope enlargement to identify.
Aeciospores are wind-disseminated (during July to September) and infect the leaves of
alternate host plants in late summer to early fall.
In the following spring, uredinia (with urediniospores) develop on the leaves of alternate
host plants and overwinter, producing telia (with teliospores) and basidiospores in the following
spring.
Detection and Damage
Look for the following signs and symptoms:
* Infected wintergreen leaves in mid- to late-summer may be atrophied, chlorotic, and less shiny
than uninfected leaves.
* Diseased cones become evident in mid- to late-summer when they turn light brown, dry, and
the scales open prematurely releasing powdery yellow-orange spores (aeciospores).
* Note orange-colored pustules (uredinia and telia) on the under surface of alternate host plant
leaves, indicating presence of the disease.
Up to 50% or more of a cone crop can be infected in localized areas and most of the seeds in
infected cones are not viable or show poor germination. Seeds from infected cones generally have
reduced weight.
Management
* Control of spruce cone rust disease is not practical in wild stands of spruce but may be
necessary for protection of the seed crop in high value seed orchards.
* Avoid collecting infected cones in the fall because of their low and poor quality seed yield.
* Seed orchards established in areas where alternate host plants are abundant are at high risk for
infection.
* Control or reduction of alternate host plants adjacent to seed orchards may reduce cone
infection risk.
* Cone rust infection in seed orchards may be reduced by an appropriately timed fungicidal
application.
* Monitoring certain weather factors such as periods of high humidity and wind conditions can
help to predict basidiospore infection of conelets in the spring.
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