Tree Insects and Forest Disorders

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Insect Categories

Defoliators

• Defoliators are known to eat or destroy the leaves or foliage off of the trees.

• Defoliators are classified based upon whether they attack conifer or hardwood trees.

• Common defoliators are pine webworm, bagworm, conifer sawfly, Eastern tent caterpillar, fall webworm, gypsy moth, and orangestriped oakworm.

Types of Defoliators

Conifer Defoliators

Pine Webworm

• The pine webworm can cause extensive damage in young pine stands. Most GA pines are attacked. It primarily attacks 1-2 year old seedlings.

• The larvae feed on the needles constructing masses of frass (waste) bound together with silk on the seedlings Masses are usually 3”-5” long surrounding the twigs and enclosing the basal portions of needles. Control is not necessary.

• The adult’s wingspan is approx 1 inch wide.

Pine Webworm

• This is the mass of frass that is made by the pine webworm.

Bagworm

• Bagworm is common on junipers, arborvitae, bald cypress, & other conifers & are known for the bags on the trees.

• The females are wingless & stay in bag for life. The males fly & will locate the females in fall & mate. Each female may lay 800-1000 eggs/yr.

• Upon hatching each larva constructs a small bag made from silk, leaves, and twigs. Larva carries bag wherever it goes.

• Full grown bags may reach 2” or more per year.

Bagworm – Cont’d

• There is only one generation per year.

• The larvae consume entire needles leaving only the sheath behind.

• The bags can be picked by hand and destroyed or trees can be sprayed with insecticides just after larvae appear.

Conifer Sawfly

• Loblolly and longleaf pines are the preferred hosts.

• They feed on needles and leaves on trees under 15 feet.

• Sometimes eat tender bark when foliage is scarce.

• After attack the unconsumed portions of leaves have straw-like appearance

Conifer Sawfly – Cont’d

• Known for their bright red head and yellow body with rows of black spots

• There are 2 generations per year.

• Natural factors and climatic conditions help control

• Chem. Control is sometimes necessary.

Conifer Sawfly – Cont’d

• This is the conifer sawfly.

• Notice the red head, yellow body, and the black spots.

Hardwood Defoliators

Eastern Tent Caterpillar

• Feed on mostly black cherry and other members of the genus Prunus.

• Feeds on cherry, apple and plum trees.

• They have black head and body with yellow and white stripes.

• Construct silk tents in the tree forks.

Eastern Tent Caterpillar –Cont’d

• There is only one generation per year.

• Caterpillars can be handpicked from the communal tents.

• Prune off tents and burn.

• This is the larva

Fall Webworm

• Feeds on pecan, sourwood, & persimmon

• They construct ugly nests of silk around the leaves.

• The caterpillars can be removed by hand, but larger trees need to be sprayed with high-pressure equipment.

• Eggs are yellow or light green turning gray.

Fall Webworm – Cont’d

• A fuzzy larva but pure white moth.

• Natural enemies usually keep under control. Chemical control may occasionally be necessary.

• There are at least 2 generations in the South per year.

• They are fuzzier than the Eastern Tent Caterpillar.

Gypsy Moth

• Eat on most hardwood species mostly red and white oaks.

• Also likes alder, apple, basswood, willow, birch, hemlock, cedar, pine, spruce

• A serious spring defoliator of forest and shade trees.

• The destructive stage is the caterpillar.

Gypsy Moth – Cont’d

• It was brought to the U.S. from France – not native

• Females are larger when moths with 1 generation per year.

• Controls like parasites and weather are effective.

• This is the larva of a gypsy moth.

Orangestriped Oakworm

• Attacks oaks as name implies

• The greatest damage is aesthetic impact and nuisance.

• It is black with 8 narrow yellow stripes

• There is one generation per year

• The best control method is its natural enemies.

Bark Beetles and Borers

• These insects feed on the bark of the tree.• Some insects under this category will bore into

the tree through the bark.• Common bark beetles and borers are the:

Southern Pine Beetle, Ips Engraver Beetle, Black Turpentine Beetle, Ambrosia Beetle, and Southern Pine Sawyer.

• These insects do not attack hardwoods, only conifers.

Bark Beetles and Borers

Southern Pine Beetle

• The most destructive pine beetle in the South.• The susceptible trees (focus trees) include all

species of southern yellow pines and the eastern white pine, especially in over mature or overcrowded stands.

• They attack by boring holes underneath the bark to feed and lay eggs. Adults carry blue stain fungi and these fungi will increase and cut off the water movement in the tree. The fungus can also interfere with SPB development.

SPB – Cont’d

• Symptom of SPB infestation – s-shaped egg galleries in the cambium and pitch tubes in the bark crevices

• Several broods are produced per year.• The removal of all trees by salvage is best or by

cut-and-leave (felling infested trees with buffer of uninfected trees and leaving them in forest)

• Chemical control is limited and only for small outbreaks. Pile and burn is effective for pre-commercial sized trees.

SPB – Cont’d

• These are the s-shaped galleries and pitch tubes that the SPB construct in the cambium to lay their eggs in.

SPB – Cont’d

• This is an adult.• It is smaller than the

Black Turpentine Beetle and is reddish brown in color.

Ips Engraver Beetle

• Can be distinguished by their scooped out posterior - Jagged look.

• Several generations per year.• Don’t always produce pitch

tubes.• When there are pitch tubes

they are usually on the bark flakes and not in the crevices.

• Outbreaks usually don’t require treatment.

IPS Engraver Beetle

• Tree death is hastened by blue stain fungus.

• The best control is speedy removal and utilization of actively infested trees and making sure that the bark and slabs are destroyed.

Ips Engraver Beetle

• They have vertical egg galleries

• They kill more pine timber with the exception of the SPB.

• They have y or h shaped egg galleries.

• They are the most common species of Bark Beetle in the South.

Black Turpentine Beetle

• Prefers trees damaged by logging & landscaping equipment & lightning. Outbreaks also preceded by drought.

• Pitch tubes - size of a quarter & occur in the bark crevices

• Attacked trees can be treated effectively with an approved insecticide b/c it only infests the lower 6 ft of the trunk.

BTB – Cont’d

• These beetles do not mass attack trees.

• It is highly attracted to the smell of pine resin.

• Attacks are observed on all pines native to the Southeast.

• They are reddish-brown to black in color.

• There are usually 2 to 4 generations per year.

BTB – Cont’d

• Beetles bore holes and lay egg in galleries formed on the face of the sapwood.

• 70 – 90% of attacked trees die.

• Weather is the most effective in controlling number of outbreaks.

Ambrosia Beetle

• Beetles prefer dying or recently cut trees, logs, and pulpwood.

• It bores into the sapwood and heartwood of logs or lumber and make pin-sized holes, each stained with fungal growth.

• This fungus is referred to as ambrosia and serves as food for larvae and adults.

• The wood is not eaten.• Beetles require wood with 48% moisture.

Ambrosia Beetle – Cont’d

• Piles of whitish boring dust around the base of tree is a good indication of an ambrosia attack.

• Prompt utilization of dead and dying trees and rapid drying of lumber can reduce losses.

• Decked logs can be protected from attack by installing water-misting systems.

• There may be several generations per year.

Ambrosia Beetle Damage

• These are the boring holes left behind by the ambrosia beetle.

• The darker places is blue stain fungus which the ambrosia beetle feeds on…remember the wood is not eaten.

Southern Pine Sawyer

• They infest southern pines, fir, and spruce.

• U-shaped cells in sapwood/heartwood

• The insects are characterized by long antennae/horns

• The 1st signs of attack are funnel shaped pits or egg niches in the bark.

• There are at least 3 generations in the South.

Southern Pine Sawyer – Cont’d

• Rapid utilization of dead or dying trees and green logs will reduce infestations and losses.

• When large numbers of trees need to be stored, they may be sprayed w/ insecticide. Logs stored in water may also prevent serious damage.

Meristem Feeders

• Meristem feeders bore into the tips of the buds, shoots, roots, etc… of trees and feed off of them.

• They feed off of the stem.

Nantucket Pine Tip Moth

• It’s the most widely distributed species and causes the most damages to recently planted pines.

• Loblolly and shortleaf are the favored hosts.

• Attacks result in stunted, bushy, and deformed trees – death is rare.

• 2-5 generations occur per year.

• It’s shaped like a pine tree seed.

Nantucket Pine Tip Moth Damage

• This is damage done by a Nantucket Pine Tip Moth.

• Chemical control is not practical. The best method is through setting pheromone-baited traps.

Pales Weevil

• Pales Weevil chews bark from the stem above and below the ground.

• They are attracted to recently logged areas w/ pine stumps.

• #1 Characteristic: elephant like snout

Pales Weevil – Cont’d

• It’s the most serious pest of pine reproduction in the Southeast.

• Most coniferous and all southern pines are attacked.

• Adults feed on the tender bark of seedlings or twigs of trees.

• Control: Delay planting in cut-over areas for at least 9 months or treat seedlings with suitable insecticide.

Piercing and Sucking Insects

• These insects suck the plant juices (sap, etc…) from the foliage and bark of twigs and stems.

Aphids

• Aphids are soft-bodied, pear-shaped insects varying in color from red, yellow, green, blue, brown, gray, or black.

• Adults may be winged or wingless.

• Most species have pair of tube-like cornicles coming from the 5th or 6th ab segment.

Aphids – Cont’d

• They infest hardwoods and conifers almost anywhere on the tree.

• They distort foliage; in young trees it can cause death.

• Honeydew and sooty mold (explained on next slide) mar beauty of ornamental trees.

• Some aphids have 1 generations/year and others have several.

• Parasites and natural enemies usually control but insecticides are used on high value trees.

Aphids – Cont’d

• In addition to sucking sap from foliage and bark, aphids also excrete large amounts of honeydew that may drop from trees.

• Honeydew is simply the sap that is sucked in through the beak and only partially digested and excreted.

• It is sweet and sticky…ants feed on it.

Scales

• Scale insects are injurious to pines in seed orchards and a nuisance to Christmas tree plantations.

• Different species attack different parts of the host, branches and twigs being frequently infested.

• There may be 1-6 generations per year varying w/ species and geographical location.

Scales – Cont’d

• Scales affect hardwoods and conifers.• They are of greatest concern with nurseries, seed

orchards, shade & ornamental trees.• Some scales have only 1 generation per year and

others have several.• Parasites and predators are effective in

controlling infestations but insecticides are used on high value trees.

Scales – Cont’d

• They extract sap from plant parts causing devitalization and death of the infested parts. Some scales produce galls.

• They can cause needle yellowing, stunted growth, dieback, and heavy sooty mold.

Cicadas

• Cicadas attack young trees. • Method of Attack: the females lay large amounts

of eggs in the young trees• The large insects have large membranous wings

(bigger than their body) and large compound eyes.• The nymphs pierce and suck from the roots.• Symptoms of attack: there are y-shaped pits in

living twigs and smaller branches.• Control is not usually necessary.

Diseases

Hardwood Diseases that attack Foliage and Twig

Black Knot

• Prevalent throughout the Southeast wherever black cherry is grown and in orchards on plums and domestic cherries.

• Symptoms include the black swellings which appear in the summer on small twigs and branches.

• Outbreaks on black cherry trunks usually ruin the commercial value.

• Diseased branches should be pruned and destroyed. Twigs and branches w/ knots should be burned.

Black Knot – Cont’d

• Infections are started by spores which germinate and infect the current years trees. Fungus fruiting bodies (which have many sacs (asci) that hold the spores) develop on the surface of the knot. In rainy weather, spores are discharged into the air and carried to the new growth. If trees remain wet long enough, infection may occur.

Conifer Diseases that attack…

Foliage Diseases (Conifer)

Needle Casts

• Infected trees in forest stands usually recover.• There are over 25 needle cast fungi in the South.• No controls are practical in forest stands.• Fungicide may be applied in Christmas tree plantings

and nurseries.• Needles begin to turn yellow-brown by winter or early

spring.• Later browning progresses and fungal fruiting bodies

may be bordered by brown or yellow margins, or both. In the more advanced stages, the tree has a scorched appearance.

Brown Spot Needle Blight

• Attacks all southern pines but only longleaf are seriously damaged (long name=longleaf)

• Affects both planted and natural seedlings in the field.

• Can be controlled in nurseries by spraying with an approved fungicide. Prescribed burning is recommended for control in plantations.

Brown Spot Needle Blight – Cont’d

• Needles in early stages are irregularly yellow to brown spotted with green tissue in between the spots.

• Needles are eventually killed by the girdling action of the fungus.

Pine Needle Rust

• Alternate hosts are generally golden rod and aster.

• Most noticeable symptoms are the bright orange aeciospores on the pine needles in the spring when weather conditions are favorable for disease development.

Pine Needle Rust – Cont’d

• No chemical controls are recommended for this disease either under forest or shade tree conditions. Elimination of the alternate host in the vicinity of the pines should reduce the incidence of infection.

Cedar Apple Rust

• During wet weather in the spring, gall rusts produce bright orange gelatinous finger-like masses of spores.

• Red cedar should not be planted near apple orchards as apple, hawthorn, and crabapple are alternate hosts to the rusts and some species may be severely defoliated. No chemical control is recommended.

Root & Butt Rot and Decay

Annosus Root Rot – Cont’d

• Occasionally the fungus will develop fruiting bodies of conks at the base of the infected tree. (see last slide).

• The most hazardous sites for the diseases are characterized by deep, sandy soils near the fall line.

Littleleaf Disease

• Most serious disease of shortleaf pine in South.

• Caused by fungus, low soil nitrogen, and poor drainage.

• Fungus kills the root tip of the stressed tree.

• Tree usually dies about 6 years after 1st symptoms appear.

• The amount of littleleaf dictates the management of that stand.

Littleleaf Disease

• 1st Symptom: yellowing and shortening of needles and reduction of shoot growth.

• Later stages: crown of tree appears thin and tufted. New needles are discolored and tree loses all but the new needle near tips of branches.

• Undersized cones• Rarely occurs in trees less

than 20 yrs old.

Stem, Branch, and Cone (Conifer)

Fusiform Rust

• The most damaging disease of loblolly and slash pines throughout South.

• Causes stem and branch cankers (galls) to form on infected trees.

• Infection occurs before age 5.

Fusiform Rust – Cont’d

• Galls produce yellow-orange spores (aeciospores) that are windblown to young, tender oak leaves. Water, willow, and laurel oaks are the most affected.

• Control methods are complex and numerous.Avoid planting loblolly and slash around oaks that are affected.

Pitch Canker

• Can infect most of the Southern pines but more damage is done to slash, shortleaf, and Virginia pines.

• Gains entrance into trees through wounds and insect feeding sites made by pine tip moths, the deodar weevil, and beetles.

• The tips of terminal and lateral branches are usually girdled and killed.

Pitch Canker – Cont’d

• Infected trees should be removed during thinning.

• Consider using the seed tree method b/c native seed sources may be more resistant than nursery seedlings.

• Regulate stocking densities to avoid overcrowding and individual tree stress.

Other Diseases

Herbicide Damage

• Often occurs along highway, railroad, and other utility rights-of-way.

• Damage may take the appearance of twisting of the foliage, stunting, curling, witches’ broom or blighting, depending upon the herbicide and concentration and tree species.

• Volatile fumes from herbicides may damage or kill many species of ornamental plants.

• Herbicides should not be applied when the wind is over 5 miles per hour and never directly to a tree that is not to be killed.

Slime Flux

• Sap bleeds through wound in bark.

• Oaks, elms, and maples are often affected but some softwoods are also susceptible.

• Cannot be cured.• Usually diminishes after

several years w/ or w/o drainage pipes and shade tree owners should regard slime flux as non-life-threatening event.

Mistletoe

• Popular around Christmas.

• Parasitic on hardwoods.

• Birds and other tree dwelling animals can spread seed.

• Heavily infested trees cannot thrive.

• Most effective way is to prune off infested branches at least 3 ft below mistletoe.

Wildlife/Livestock Damage

Beavers

• Timber stand can suffer substantial loss when stands are flooded as a result of damming.

• Trapping is an effective method in reducing beaver in local areas, but it must be kept up for a long period of time for complete control.

Deer Damage

• Deer damage young pine stands by feeding on the terminals of recently planted pine seedlings.

• They are heaviest in February or March.• The seedlings are clipped straight across; also

oval droppings will be present throughout the area.

• Animal repellants provide short-term control but are not economical for large areas.

Cotton Rats, Meadow Voles, and Pine Voles

• Damage young pine stands by gnawing at the base of trees.

• Frequent mowing between rows of trees can reduce damage and so can prescribed burning by reducing cover.

• Pine Voles damage young pines by feeding underground and stripping the lateral roots.

Rabbits

• Damage seedlings by gnawing or biting them off at various heights.

• Signs: Rabbits clip seedlings off at an angle (unlike deer), round droppings will usually be present at base or near base of damaged seedlings.

Squirrels

• Not considered serious pests of forest trees but when trees have been affected by drought or other phenomenon, trees in forests, cities, and yards, can be seriously damaged.

• Can be completely stripped of their bark on most branches.

• In time, natural forces tend to reduce squirrel overpopulation.