Insects And Diseases Of Trees In The South

INSECTS AND DISEASES OF TREES IN THE SOUTH

U.S. Department of Agriculture—Forest Service State and Private Forestry—Southeastern Area Forest Pest Management Group...

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INTRODUCTION

This publication has been prepared to assist forest managers and homeowners in identifying pests of southern trees. The insects and diseases discussed are the more common ones attacking forest and ornamental trees. Prompt identification and treatment of these pests may mean the difference between losing or saving a valuable shade tree. Underlying all successful forest and ornamental pest control efforts, however, is the necessity to keep trees in a healthy, vigorous condition. We have attempted

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ELM SPANWORM, Ennomos subsignarius (Hbn.)

The elm spanworm is a native insect which is widely distributed over the eastern half of the United States and Canada from Nova Scotia south to Georgia and west to Colorado. The most widespread outbreak on record occurred during the period 1954-1963 when over one million acres of hardwood forests were defoliated in the mountains of western North Carolina, eastern Tennessee and northern Georgia. The elm spanworm feeds upon hickories and a variety of hardwoods; white oak, chestnut oak, and norther

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FALL CANKERWORM, Alsophila pometaria (Harris)

The fall cankerworm is widespread in the northern part of the United States, ranging south through the Appalachian Mountains to North Carolina. Larvae defoliate many species of hardwoods, but in the South seem to prefer oaks, hickories, and ash. Mature fall cankerworm larva. The winged male and wingless female adults emerge on mild days in November and December and mate. Females lay 6-300 eggs in neatly arranged masses encircling small branches and twigs. The pale green larvae hatch in late Apri

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A LOOPER, Phigalia titea (Cramer)

Larvae of this moth, one of the measuring worms, have periodically been responsible for scattered mortality of hardwoods throughout the eastern United States. Mortality is most likely to occur in stands on low-quality sites, particularly during periods of drought which favor this insect’s development and further weaken infested trees. This species is likely to be found in almost any hardwood area in the eastern United States. The insect feeds on a wide variety of trees and shrubs. Host trees in

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EASTERN TENT CATERPILLAR, Malacosoma americanum (F.)

The presence of the eastern tent caterpillar is objectionable more from an aesthetic standpoint than from its effect on the host tree. The ugly tents constructed by the feeding larvae make this pest highly objectionable on shade trees. Black cherry and other species of the genus Prunus are preferred hosts, but other trees in the family Rosaceae are sometimes attacked. This insect is widely distributed wherever host trees are found east of the Rocky Mountains. Larvae and tent of eastern tent cate

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FOREST TENT CATERPILLAR, Malacosoma disstria (Hbn.)

The forest tent caterpillar has caused repeated serious defoliation of hardwood forests throughout North America. Aspen, water tupelo, hard maple, gums, and oaks are preferred hosts but this insect will feed on a variety of other broadleaf trees. Forest tent caterpillar larvae. The shiny black egg masses encircling the twigs of host trees can be seen during winter months. Small black, hairy larvae hatch out just as the leaves are beginning to unfold. They do not construct a tent, but make a silk

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FALL WEBWORM, Hyphantria cunea (Drury)

The fall webworm is not considered an important forest pest. However, ugly webs can seriously detract from aesthetic values. The preferred hosts in the South are persimmon, pecan, and sourwood, but it is also found on black walnut, hickory, cherry, sycamore, crab apple, and sweetgum. The insects range throughout North America. Fall webworm larva. The adult is a pure white moth about 1¼ inches long. The forewing is sometimes marked with blackish dots. The larva is about one inch long when full gr

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OAK LEAF TIER, Croesia albicomana (Clem.)

This oak leaf tier has been associated with the decline and mortality of several species of oak in the northeastern United States and southern Appalachians. An outbreak population in the mountains of West Virginia and Virginia in 1966-68 resulted in the loss of several thousand acres of scarlet oak. Usually such outbreaks coincide with periods of drought which increase the impact of defoliation on the host. Its hosts include northern red oak, black oak, scarlet oak, and pin oak. The latter two s

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VARIABLE OAK LEAF CATERPILLAR, Heterocampa maneto (Dbldy.)

The variable oak leaf caterpillar periodically defoliates extensive areas of hardwood forest in the eastern United States. Its range covers all of the southern and eastern states as far west as east Texas. The larvae feed primarily on oaks but will also feed on beech, basswood, birch and elm. Other defoliating insects may be associated with outbreaks causing additional damage. Young larvae skeletonize the leaf while older larvae devour the entire leaf except the primary veins. Infestations are g

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LOCUST LEAFMINER, Xenochalepus dorsalis (Thunberg)

The locust leafminer is a destructive pest of black locust and honey locust in both the adult and larval stages. It is found throughout the range of these trees in the eastern half of North America. The adults also feed on other species of trees. The adult beetles overwinter in crevices in the bark of trees and under litter on the forest floor. The beetles emerge and begin feeding in the spring, usually after mid-April. After feeding for a short time they deposit eggs on the undersides of leaves

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COTTONWOOD LEAF BEETLE, Chrysomela scripta (F.)

Willows, poplars, aspens and alders are attacked by the cottonwood leaf beetle in the eastern United States. Cottonwood is the most important host in the South. Damage has been especially severe in Louisiana and Mississippi where thousands of acres of cottonwood plantations are intensively managed. Adult beetles and larvae feed on the foliage. Damage is most critical during the first three years after the cottonwood is planted. Adults chew holes in the leaves and may attack the terminal shoots c

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WALKINGSTICK, Diapheromera femorata (Say)

The walkingstick is a defoliator of broadleaved trees in North America. The black oaks, basswood, and wild cherry are the most common preferred hosts but numerous other hardwood species are attacked. This insect is widely distributed over the United States east of the Rocky Mountains as well as Manitoba and Ontario in Canada. At times, populations build in sufficient numbers to defoliate trees over large areas. Male walkingsticks feeding on oak. These slender, wingless, stick-like insects are pa

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GYPSY MOTH, Porthetria dispar (L.)

The gypsy moth is an introduced forest insect. It was brought into this country from Europe in 1869 and has been restricted to the Northeast. The gypsy moth feeds aggressively on oak, alder, apple, basswood, willow, and birch. As the caterpillars reach maturity they will also feed on hemlock, cedar, pine, and spruce. Gypsy moth larvae. In the Northeast, the gypsy moth has a single generation per year, overwintering in the egg stage. Eggs hatch in late April and May and larvae are present for app

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HICKORY BARK BEETLE, Scolytus quadrispinosus (Say)

The hickory bark beetle is reported to be the most serious insect pest of hickory in the United States. Population explosions where thousands of trees were killed have been reported from New York, Pennsylvania, Maryland, Virginia, and recently from Georgia. Hickory bark beetles are distributed throughout the range of their host in eastern United States. All species of hickory are subject to attack, as well as pecan and possibly butternut. Adult beetles emerge in May and June in the southern port

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SMALLER EUROPEAN ELM BARK BEETLE, Scolytus multistriatus (Marsham)

The smaller European elm bark beetle was first reported in the United States in 1909. Its presence in this country was given significance with the introduction of the Dutch elm disease in 1930. The beetle attacks all native and introduced species of elms and now occurs wherever the hosts are present. The feeding of the adult beetles in the spring is responsible for transmitting the Dutch elm disease from diseased to healthy trees. The Dutch elm disease is now our most important shade tree diseas

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COLUMBIAN TIMBER BEETLE, Corthylus columbianus (Hopkins)

All hardwood trees in the eastern half of the United States are subject to attack by the Columbian timber beetle, but oaks, maples, birch, basswood, yellow-poplar, and elm are the preferred hosts in the South. The beetle causes two major types of damage: 1) physical damage caused by the 1/32″ to 1/16″ hole excavated by the adult into the sapwood, and 2) degrade caused by stain which may extend for a considerable distance above and below the gallery. Large diameter trees are preferred as hosts, b

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COTTONWOOD TWIG BORER, Gypsonoma haimbachiana (Kearfott)

The cottonwood twig borer is widely distributed throughout the entire range of eastern cottonwood, from Canada to the Gulf States and west to Missouri. The larvae of the cottonwood twig borer feed in the terminals of the host. This feeding results in reduction of terminal growth and forked and crooked trunks. Damage is especially severe on young trees. Cottonwood twig borer damage to cottonwood sapling. Three-year-old cottonwood stunted by twig borers. The female moth lays eggs on the upper surf

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COTTONWOOD BORER, Plectrodera scalator (F.)

The cottonwood borer is limited in range to the southern half of the United States. Hosts include cottonwood, poplars and willows. The adults feed on the tender shoots of young trees causing them to shrivel and break off. The larval stage of this insect tunnels in the inner bark and wood at the base of the tree and may kill or severely weaken it. Adult cottonwood borer. The adult beetles appear in midsummer. After feeding briefly on the tender bark of the terminals the adults descend to the base

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WHITE OAK BORER, Goes tigrinus (De Geer)

A recent survey of damage caused by various wood borers to three species in the white oak group revealed an estimated annual loss in the South exceeding 20 million dollars. One of the more important borers responsible for this damage is the white oak borer. Adult white oak borer. Usually the white oak borer attacks oaks one to eight inches in diameter. The damage, like that of other hardwood borers, is the result of larval feeding in the wood. Galleries up to one-half inch in diameter extend upw

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RED OAK BORER, Enaphalodes rufulus (Hald.)

The red oak borer is a serious pest of trees in the red oak group. It ranges throughout eastern North America wherever host species grow. It is estimated that defects caused by larval tunnels in the sapwood and heartwood of host trees costs the hardwood timber industry millions of dollars each year. Adult red oak borer. Eggs of the red oak borer are laid during early and mid-summer in bark crevices or under patches of lichen on host trees. After hatching, larvae bore into the inner bark region w

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CARPENTERWORM, Prionoxystus robiniae (Peck)

The carpenterworm bores in the wood of living hardwood trees, causing costly damage to commercial timber species. In the South, oak species are preferred hosts but black locust, maples, willows, and fruit trees are also attacked. The carpenterworm is distributed throughout the United States. Carpenterworm adults. Adult moths emerge in late April to early June, mate, and the females lay groups of eggs in bark crevices or wounds. Each female lays 200 to 500 eggs during her one-week life span. Afte

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PINE WEBWORM, Tetralopha robustela (Zell.)

Ugly, compact masses of brown excrement or frass pellets around the stem of pine seedlings mark infestations of the pine webworm. Rarely is the defoliation severe enough to kill the seedlings, but it undoubtedly has an impact on growth. Found throughout the eastern United States, the webworm commonly attacks red, white, jack, loblolly, shortleaf, and slash pines. Pine webworm damage to loblolly pine. The adult moth has a wingspread of about one inch. The forewing usually is gray in the middle po

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BAGWORM, Thyridopteryx ephemeraeformis (Haw.)

The bagworm is distributed throughout the eastern half of the United States. It is generally recognized as a defoliator of conifers, particularly juniper, cedars, and arborvitae, but it is also found on many hardwood trees including maple, wild cherry, poplars, oaks, and apple. Bagworm cases on pine. The wingless, maggot-like adult female bagworms are present in September and October and spend their entire lives within the protective cover of the tough, silken bag which they construct as larvae.

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PINE COLASPIS, Colaspis pini (Barber)

Colaspis beetles are found throughout the Southeast, but are more common in the Gulf states. They seem to prefer slash pine but have been found on many of the southern pines. The pine colaspis beetle is not a serious forest pest but feeding damage caused by large populations occasionally produces a spectacular browning effect of the needles similar to that caused by fire. Adult pine colaspis beetle feeding damage on pine. The adult beetles chew the edges of needles to produce an irregular, saw-l

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PINE SAWFLY, Neodiprion excitans (Roh.)

This pine sawfly is found throughout the southeast from Virginia to Texas. Loblolly and shortleaf pine are preferred hosts, but pond, slash, longleaf, and Sonderegger pine are also attacked. The larvae do not do well on the latter two species. As with most sawflies, the larvae feed in groups on the host needles. Generally the old needles are preferred, but all of the needles are eaten when large numbers of larvae are present. Three or four young larvae usually encircle a needle and, starting fro

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ARKANSAS PINE SAWFLY, Neodiprion taedae linearis (Ross)

Loblolly and shortleaf pines are the only trees attacked by the Arkansas pine sawfly. Periodic outbreaks of this insect over large areas in the south-central states cause substantial growth losses, but the insects seldom kill trees. Arkansas pine sawfly larvae. This insect has a single generation each year. In the spring, eggs which have overwintered hatch into tiny caterpillar-like larvae. The larvae feed in groups for 30-40 days (primarily on the older foliage) before crawling to the ground an

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VIRGINIA PINE SAWFLY, Neodriprion pratti pratti (Dyar)

The Virginia pine sawfly is found from Maryland to North Carolina, and west to Illinois. The insect prefers Virginia and shortleaf pine, but it will also oviposit and feed on pitch and loblolly pine. Virginia pine sawfly larva. On warm sunny days in late October and early November, the adult sawflies emerge from their cocoons in the litter, mate, and the females lay eggs. The female is equipped with a saw-like ovipositor with which she cuts a slit at the edge of a needle and inserts a small, whi

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REDHEADED PINE SAWFLY, Neodiprion lecontei (Fitch)

The redheaded pine sawfly did not become an important pest until extensive planting of pine in pure plantations began in the 1920’s. Since then, outbreaks in young natural pine stands and plantations have been common in the South, the north-central states, and eastern states. Feeding is primarily restricted to the two- and three-needled pines under fifteen feet in height. Shortleaf, loblolly, longleaf, and slash are the species most commonly attacked in the southern states. Redheaded pine sawfly

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TEXAS LEAF-CUTTING ANT, Atta texana (Buckley)

Damage caused by the Texas leaf-cutting ant, or town ant, is confined in the United States to southeast Texas and west-central Louisiana. The ant causes damage to a variety of green plants throughout the year and causes serious damage to pine seedlings during the winter when other green plants are scarce. During this period, stands of young seedlings may be completely defoliated and the stems girdled. The ant carries bits of needles, buds, and bark back to its nest to serve as the medium on whic

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SOUTHERN PINE BEETLE, Dendroctonus frontalis (Zimm.)

Probably no other insect is of more concern to managers of southern pine forests than the southern pine beetle. Loblolly and shortleaf pine seem to be preferred hosts, but all of the southern pines may be attacked wherever they occur in North and Central America. Adult beetles are about the size of a grain of rice, stout and reddish-brown in color. While they commonly attack lightning-struck or weakened trees, they can also quickly build up to high populations capable of successfully attacking h

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IPS ENGRAVER BEETLES, Ips spp.

With the possible exception of the southern pine beetle, no other insects cause as much mortality to southern pine forests as do the three species of Ips engravers. Usually they attack severely weakened trees, lightning-struck trees, or fresh slash left by logging operations. During drought periods they can successfully attack otherwise healthy pines. Pine showing typical symptoms of Ips attack. Attacked trees are quickly girdled by the adults as they construct their egg galleries in the inner b

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BLACK TURPENTINE BEETLE, Dendroctonus terebrans (Oliv.)

The black turpentine beetle is found from New Hampshire south to Florida, and from West Virginia to east Texas. It is a particularly serious pest in the Gulf States where recent outbreaks have killed large acreages of timber. Attacks have been observed on all pines native to the Southeast, and also on red spruce. Life stages of the black turpentine beetle: adult, callow adult, pupa, larva and eggs. This is the largest of the southern bark beetles, varying in length from ⅕ to ⅓ of an inch, or abo

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AMBROSIA BEETLE, Platypus flavicornis (F.)

Ambrosia beetles are represented in the South by several species of the genus Platypus of which only P. flavicornis (F.) is known to attack dead or dying southern pines. P. flavicornis (F.) will secondarily invade other conifers and on some occasions may be found in hardwood trees. It is so abundant in the South that few dying pines, stumps, or logs escape attack. The beetle is found from Texas east to Florida and north to New Jersey. Adult of the Platypus ambrosia beetle. The adult is a reddish

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SOUTHERN PINE SAWYERS, Monochamus spp.

In the South, dying pines and fresh logs are quickly attacked by the pine sawyers. In sufficient numbers they may cause a significant loss of wood fiber and degrade sawlogs. These species are commonly found in the South infesting southern pine, fir, and spruce wherever the hosts grow. Adult southern pine sawyer beetle. The adults emerge in the spring or summer and begin to feed on the bark of twigs. After mating, the female gnaws pits through the bark of freshly felled or dying pine. The female

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NANTUCKET PINE TIP MOTH, Rhyacionia frustrana (Comstock)

The impact of the Nantucket pine tip moth on pine plantations varies widely with tree species, host vigor, and environmental factors. Heavily infested trees may be severely stunted or deformed but mortality is rare. Generally, the tree grows out of the susceptible stage within a few years. In seed orchards, the tip moth is receiving increasing attention because of its impact on height growth and, more importantly, because of its effect on flower and cone production. All species of pine within th

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PALES WEEVIL, Hylobius pales (Hbst.)

Pales weevil is perhaps the most serious insect pest of pine reproduction in the southeastern United States. Losses in susceptible areas commonly run 20-25 percent, but exceed 90 percent under circumstances favoring weevil development. Pales weevil is found throughout pine-growing regions of eastern United States and Canada. Feeding has been reported on most coniferous species, and all species of southern pines appear to be susceptible in varying degrees. Pitch-eating weevils in the genera Pachy

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WHITE PINE WEEVIL, Pissodes strobi (Peck)

The white pine weevil is generally regarded as the most serious insect pest of white pine. Although it usually does not cause mortality, trees suffering repeated attacks become stunted and deformed to the point of being commercially unusable. The weevil has become such a problem in some areas that it prohibits the growing of white pine. In addition to eastern white pine, the white pine weevils also attack Norway spruce and jack pine. Other pines and spruces are attacked to a lesser degree. The w

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PITCH-EATING WEEVIL, Pachylobius picivorus (Germar)

In the Gulf Coast States the pitch-eating weevil is probably the most troublesome insect pest of pine seedlings. No accurate figures are available on the damage directly attributable to this pest, but mortality losses are estimated to average about 30 percent in susceptible areas. All of the southern hard pines and other conifers are probably suitable breeding and host material for the pitch-eating weevil. Its range overlaps that of the pales weevil, being reported from Labrador, Canada, south t

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DEODAR WEEVIL, Pissodes nemorensis (Germ.)

This snout beetle is very similar to the white pine weevil both in appearance and habits. It is found throughout the south- and mid-Atlantic states from southern New Jersey west to Missouri. Although deodar cedar is the preferred host, Atlas cedar, Lebanon cedar, and several species of southern pines are also attacked. Galleries and chip cocoons of the deodar weevil. Adults emerge from April to May and feed briefly on the inner bark of leaders and lateral branches of host trees. Heavy feeding fr

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CONEWORMS, Dioryctria spp.

Coneworms are perhaps the most destructive insect pests of pine cones in the South. They are particularly serious in superior-tree seed orchards where they frequently cause substantial economic loss. There are five important species of coneworms in the South, one or more of which attack all of the native and exotic pines. Coneworm larva feeding on a pine shoot. Although the number of generations per year varies with the species, their general life history is similar. Female moths lay their eggs

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PINE SEEDWORMS, Laspeyresia spp.

Until recent years little has been known about pine seedworms. These insects are found throughout the South but seldom have population explosions. An exception to this is on slash pine in Florida where over 70 percent of one year’s cones were reported infested. Longleaf pine cones in Texas and Louisiana have also had over 60 percent cone infestation on occasion. Loblolly and shortleaf pine cones are seldom over 20 percent infested. Seedworms have been found infesting longleaf, loblolly, shortlea

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BALSAM WOOLLY APHID, Adelges piceae (Ratzeburg)

Eggs and wool-covered adult balsam woolly aphids. The balsam woolly aphid was introduced into northeastern North America from Europe around the turn of the century. Since then it has become a pest of major importance to true firs on the east and west coasts of the continent, and threatens some 60,000 acres of Fraser fir in the southern Appalachians. Usually the balsam woolly aphid has two generations per year in the southern Appalachians. Eggs of the first generation hatch in late June and July

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NEEDLE CAST

Needle cast is a very common disease of conifers throughout eastern and southern United States. Eastern white, loblolly, longleaf, pitch, pond, shortleaf, table mountain, and Virginia pines are all susceptible. Hypoderma lethale is probably the most common cause of needle cast on the above hosts, with the exception of longleaf pine. Lophodermium pinastri is also associated with needle cast. Hypoderma needle cast on loblolly pine. Current pine needles are infected in the early summer, and by wint

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BROWN SPOT NEEDLE BLIGHT

Brown spot or brown spot needle blight is caused by the fungus Scirrhia acicola . Brown spot occurs in all the coastal states from Virginia to Texas, and inland to Arkansas and Tennessee. All southern pines are attacked by the fungus, but only longleaf pine seedlings are seriously damaged. Brown spot needle blight on longleaf pine reproduction. Initial infection of pine needles results in the development of small, circular spots of grey green color, which later turn brown. As the fungus continue

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PINE NEEDLE RUST

Fruiting bodies of pine needle rust on loblolly pine. Nearly all the native pines in southern United States are attacked by various needle rust fungi of the genus Coleosporium . This disease is very common, but causes little harm to the trees. Many species of this rust also attack broadleaved weeds in addition to the pines, needing both host types to complete their life cycle. Needle rusts are most prevalent on young trees in the seedling to sapling stage. In the spring or early summer small, de

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CEDAR APPLE RUST

Cedar apple rust, caused by Gymnosporangium juniperi-virginianae , is important commercially in the apple-growing regions of the Virginias, Carolinas, and the Mississippi Valley. The alternate hosts of this rust are eastern red cedar and several species of junipers. Fruiting galls containing spores on cedar tree. Fruiting on apple leaf the alternate host. Cedar “apples” or galls are the characteristic signs of the fungus on cedars. Cedar needles are infected in the summer by wind-borne spores fr

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CEDAR BLIGHT

Cedar blight, caused by Phomopsis juniperovora , is most severe on eastern red and Rocky Mountain cedars. Other hosts include arborvitae, cypress, and Atlantic white cedar. The disease ranges from the mid-West to the Atlantic coast and south to Alabama where it is most common in nurseries. Needle symptoms on 1-0 eastern red cedar nursery stock and 5 year old Arizona cypress. Symptoms on red cedar resemble that of drought. The tips of branches are killed back and sometimes entire trees will turn

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FUSIFORM RUST

Galls on 1-0 pine nursery stock. Damage caused by fusiform rust infection. Fusiform rust, caused by Cronartium fusiforme , is one of the most important diseases on southern pines. This rust is found from Maryland to Florida and west to Texas and southern Arkansas. The rust’s most important impact is in nurseries, seed orchards, and young plantations. Loblolly and slash pines are very susceptible to this rust. Pitch and pond pines are moderately susceptible, longleaf pine is fairly resistant, and

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WHITE PINE BLISTER RUST

White pine blister rust, caused by Cronartium ribicola , was introduced to North America on nursery stock about 1900. It is the most important disease on white pine in the United States. In the South, the disease is found on eastern white pine in the Appalachian mountains. Fruiting cankers showing yellow-colored spores of blister rust on eastern white pine. The disease is caused by a fungus that attacks both white pine and wild and cultivated currant and gooseberry bushes, called Ribes . Both ho

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COMANDRA BLISTER RUST

Fruit gall showing orange colored spores on loblolly pine. Alternate host—false toadflax. Comandra blister rust, caused by the fungus Cronartium comandrae , is a canker disease of hard pines. The disease presently occurs in widely scattered areas throughout the western, central, and southern United States. In the South, the primary hosts are loblolly, shortleaf, pond, and Virginia pine. Herbaceous plants of the genus Comandra, commonly known as false toadflax or comandra, are also attacked. The

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EASTERN GALL RUST

Eastern gall rust, caused by the fungus Cronartium cerebrum , attacks many species of eastern hard pines. The disease ranges eastward from the Great Plains and is most severe in the South on Virginia and shortleaf pines. Like most rusts this fungus requires an alternate host in addition to its pine host. In this case oaks, especially the red oak group (black, red, scarlet and pin) are the alternate hosts. Damage to the oaks is generally not of economic importance as only the leaves are affected.

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SOUTHERN CONE RUST

Southern cone rust is caused by the fungus Cronartium strobilinum . It has been reported to completely destroy slash and longleaf pine cone crops in Georgia and along the Gulf Coast from Florida to Texas. Cone rust symptoms on slash pine. Like most other rusts, the fungus requires oaks and pines to complete its life cycle. Although infection of oak leaves occurs annually, no significant economic damage is done to the oaks. Fungus spores produced on oak leaves infect the mature female pine flower

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PITCH CANKER

Pitch canker, caused by the fungus Fusarium lateritium forma pini , is rapidly becoming widespread throughout the South. The disease apparently is most serious on Virginia, slash and south Florida slash pine. The fungus also attacks shortleaf, pitch, and table-mountain pine. Pitch canker infection in terminal branch and main stem of pine. Pitch canker may cause tree mortality. On Virginia pines the fungus reportedly enters through small insect wounds in the twigs or mechanical wounds in the bole

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WOOD DECAY

Wood decay of southern forest trees is responsible for nearly 80 percent of all loss attributed to disease. This decay is caused by fungi which mainly attack heartwood in the central portion of stems, branches, and roots. Wood-rotting fungi gain entrance into the tree through broken branches, wounds, and damaged or exposed roots. Spores, which land at these damaged areas, germinate and produce a microscopic mycelium which attacks and spreads throughout the heartwood. The decay is caused by the a

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RED HEART

The fungus, Fomes pini , is the cause of a heartrot of widespread distribution. Common names for the rot produced by this fungus are: red heart, red ring rot, or white peck. The disease is commonly associated with mature and over-mature conifers, especially Douglas fir, larch, spruce, and pine. In the southern United States, the fungus attacks all species of mature pine. Fruiting body of redheart on southern pine. Generally, infection of all hosts occurs through dead branch stubs. Early stages o

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ANNOSUS ROOT AND BUTT ROT

Fomes annosus fruiting bodies on stump. Annosus root and butt rot is caused by the fungus Fomes annosus . This pathogen is common throughout coniferous stands of the North Temperate Zone. Hardwoods may be attacked, but damage is usually of minor consequence. In the South, the disease is most serious in pine plantations on sandy soils with low organic matter. All species of southern pine are susceptible. Slash and loblolly plantations are often severely affected. The disease gains entry into plan

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BROWN CUBICAL BUTT ROT

Polyporus schweinitzii is a common cause of root and butt rot of conifers throughout North America. The primary hosts of the fungus are Douglas fir, spruce, and pine. All southern pines are susceptible to attack by P. schweinitzii . Common names of the rot are: red-brown butt rot and brown cubical butt rot. Fruiting body of brown cubical root and butt rot of pine. The fungus enters living hosts through damaged roots, fire scars, and other wounds near the tree base. The initial stage of decay app

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RED ROOT AND BUTT ROT

Fruiting body of red root and butt rot of pine. Polyporus tomentosus causes red root and butt rot of living conifers throughout North America. Common hosts of the fungus are: spruce, larch, pine, fir, Douglas fir, hemlock, and cedar. Throughout the southern United States, P. tomentosus has been reported in two general areas; causing extensive degrade of mature shortleaf pine in northern Arkansas and root and butt rot of slash pine in South Carolina, Georgia, and Florida. The fungus is believed t

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LITTLELEAF OF PINE

Littleleaf of pine, caused by Phytophthora cinnamomi , is the most serious disease of shortleaf pine in the Piedmont region of the South. Loblolly is also affected, usually where associated with infected shortleaf pine. The disease is most evident in older age classes, rarely attacking stands under 20 years old. Needle symptoms and damage of littleleaf on shortleaf pine. The disease is caused by a malfunctioning of the root system due to a combination of biological and physical factors. A fungus

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SYCAMORE ANTHRACNOSE

Defoliation of sycamore tree caused by sycamore anthracnose. Sycamore anthracnose, caused by Gnomonia veneta , is common on American sycamore throughout its range in the eastern United States. Anthracnose is a disease characterized by distinctive limited lesions on stem, leaf, or fruit, often accompanied by dieback or blight and usually caused by fungi that produce slimy spores that ooze from small cup-shaped fruiting bodies that are visible with a hand lens. This disease has four distinct sympt

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WALNUT ANTHRACNOSE

Walnut anthracnose is a fungus disease caused by Gnomonia leptostyla . This worldwide disease attacks most species of walnut in the United States. Black walnut is most severely affected, but with favorable weather for the fungus, even less susceptible individuals may be defoliated. Butternut, Persian walnut, and two species from California (Hinds walnut and California walnut) are all susceptible. Anthracnose has also been reported on species of walnut from most of the European countries, Argenti

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OAK ANTRHACNOSE

Leaf symptoms of oak anthracnose. Oak anthracnose is caused by the fungus Gnomonia veneta . Trees of the white oak group, particularly white oak, are susceptible to this disease. Oaks throughout the entire eastern United States are affected by the disease, although it is less common in the Northeast. Infection occurs in the early spring or mid-summer. Symptoms on leaves develop as irregular brown diseased areas (blotches) along the midrib and the major side veins. These blotches may grow togethe

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DOGWOOD ANTHRACNOSE

Dogwood anthracnose, caused by the fungus Elsinoe corni , occurs in states bordering the Atlantic Ocean and has also been reported in Louisiana. Its primary host is flowering dogwood, Cornus florida L. Leaf and flower symptoms of dogwood anthracnose. Anthracnose occurs in the spring and affects not only the leaves, but also the buds and “flowers”. The buds may fail to open or they may produce stunted flowers. These have many circular to elongated spots with light tan centers. Margins of these sp

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COTTONWOOD RUST

Rust infected cottonwood leaf. Cottonwood rust, caused by Melampsora medusae , is probably the most important leaf disease of cottonwoods wherever they are grown. In the Lower Mississippi Valley, all sizes of eastern cottonwood trees may be infected with this rust. However, the disease is probably of most importance in cottonwood nurseries. In mid-summer, yellow to orange pustules containing spores of the fungus form on the under surface of the cottonwood leaves. In late summer and early fall, d

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BLACK KNOT

Black swellings of cherry black knot. Black knot, caused by Dibotryon morbosum , is prevalent throughout the Southeast (with the exception of southern Florida) wherever black cherry grows, and in orchards on plums and domestic cherries. The most prominent symptoms are the elongated black swellings which appear in summer on small twigs and branches. Heavily infected trees appear quite grotesque, with large swellings which may be several times the diameter of the twigs. Cankers occurring on black

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NECTRIA CANKER

Nectria canker of hardwoods, caused by Nectria galligena and N. magnoliae , is frequently found on yellow birch and black walnut. Common hosts also include bigtooth aspen, sassafras, northern red oak, red maple, beech, Carolina poplar, paper birch, and sweet birch. A closely related canker disease is also found on yellow-poplar and magnolias. The range of this disease includes the Lake States, the Northeast, and the southern Appalachians. Target-shaped canker of Nectria on sassafras and yellow-p

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STRUMELLA CANKER

Strumella canker of hardwoods, caused by Strumella coryneoidia , most frequently attacks trees of the red oak group. Other hosts include species in the white oak group. Beech, basswood, blackgum, shagbark hickory and red maple are also occasionally affected. This disease is found in the East, from the southern Appalachians to northern New England. Strumella canker on black oak. Strumella cankers are of two types: diffuse, and the more common “target-shaped.” The first develops on smooth-barked s

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SPICULOSA CANKER

Spiculosa canker, caused by Poria spiculosa , is found on bottomland oaks in the South. Occasionally this disease will also degrade hickories and honeylocust. Fruiting body of Poria rot and canker on oak. Cross section of tree showing rot and decay. Spiculosa canker is considered to be a canker-rot disease, a type of decay in which the causal organism incites not only heart-rot but also large irregular cankers. Infected trees have cankers that appear as rough circular swellings on the bole. The

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IRPEX CANKER

Irpex canker, caused by Irpex mollis , is prevalent in bottomlands and on upland areas of the Southeast. In the bottoms, Nuttall, water, and willow oaks are affected. White, chestnut, southern red, and black oaks are the hosts of this disease on upland sites. Fruiting body of Irpex rot. Cross section of tree showing rot and decay. Irpex canker is also considered to be a canker-rot disease. Symptoms on infected trees frequently involve irregular cankers up to two feet in length. Cankers are usual

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HISPIDUS CANKER

Polyporus hispidus is the cause of trunk cankers and localized decay of hardwoods throughout eastern, central, and southern United States. The fungus is also known to attack hardwoods in Oregon and California. Reported hosts are: hickory, ash, mulberry, willow, walnut, and oak. In the south, P. hispidus is common on oaks, including willow, water, black, white, Nuttall, and cherrybark. Fruiting body and canker of Hispidus on oak. The fungus usually enters the tree through dead branch stubs, from

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BOTRYOSPHAERIA CANKER

Botryosphaeria ribis causes cankering and mortality of more than 50 woody plants. The fungus is widely distributed throughout the eastern one-half of the United States. The pathogen infects the following economically important hosts: sweetgum, redbud, willow, poplar, tupelo, pecan, and hickory. Botryosphaeria canker on sweetgum. The fungus gains entry into susceptible hosts primarily through wounds or dead and dying twigs. Small oval cankers on stems or branches are the first symptoms of infecti

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SEPTORIA CANKER

Septoria canker on young cottonwood saplings. Septoria canker is caused by the fungus Septoria musiva . Although this is a disease of poplars, native poplar species are not severely attacked. However, this is an important problem wherever hybrid or introduced poplars are grown. With the ever-increasing emphasis on poplar planting, this will probably become a much more important problem in the near future. Young stem cankers usually develop around openings such as wounds, lenticels, or leaf scars

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CYTOSPORA CANKER

Cytospora canker is caused by Cytospora chrysosperma . This fungus attacks more than 70 species of hardwood trees and shrubs as well as some conifers. Poplars and willows are among the most common hosts, and are attacked throughout their range. Trees used for shade or windbreak, and also cuttings in propagation beds are particularly susceptible to this canker. This disease is most severe on trees growing under stress, such as those growing on an unfavorable site, or injured by drought, frost, fi

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CHESTNUT BLIGHT

Stem canker caused by chestnut blight organism. Chestnut blight is caused by the fungus Endothia parasitica . It can be found on American chestnut throughout its range where it has virtually eliminated this valuable species from eastern hardwood forests. The chestnut blight fungus is also parasitic on other hosts including common chinkapin, Spanish chestnut, and post oak. Japanese and Chinese chestnuts are resistant. Stem cankers are either swollen or sunken and the sunken type may be grown over

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OAK WILT

This serious vascular wilt of oaks is caused by the fungus Ceratocystis fagacearum . At least fifty species and varieties of oak are susceptible. The disease has been most damaging in the Lake States but is also found in the eastern United States. Oak wilt symptoms on red oak trees and leaves. Oak wilt symptoms are most noticeable during late spring or early summer. Red oaks may be killed in as little as three weeks, the lower branches being affected last. In white oaks, symptoms are usually con

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DUTCH ELM DISEASE

Dying tree infected with Dutch elm disease. Dutch elm disease, caused by Ceratocystis ulmi , is the most devastating disease of elm trees in the United States. This disease has been recorded in most states east of the Mississippi and as far as Idaho in the Northwest and Texas in the Southwest. All of the native elm species are susceptible, while many of the ornamental Asiatic species are highly resistant. Trees suffering from Dutch elm disease may show a variety of symptoms. Leaves become yellow

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ELM PHLOEM NECROSIS

Elm phloem necrosis is a disease of elm, caused by a virus or virus-like organism. The disease has occurred in the United States for many years, probably as early as 1882. The pathogen is transmitted from infected to healthy trees by the adult white-banded elm leafhopper, Scaphoideus luteolus , which feeds on the leaf veins. It is now present throughout most of the central, eastern, and southern portions of the United States. The disease is known to occur on American and winged elm, but all nati

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MIMOSA WILT

Mimosa branches showing wilt symptoms. A vascular wilt of the mimosa (silktree) is caused by the fungus Fusarium oxysporum forma perniciosum . The fungus is known only to attack the mimosa, a tree imported from eastern Asia and grown throughout the southeast as an ornamental. Since the discovery of the disease in North Carolina in 1935, the fungus has spread north to Maryland, south to Florida, and west to Texas. The fungus causing mimosa wilt is soil-borne and gains entrance into the tree by at

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VERTICILLIUM WILT

Verticillium wilt, caused by common soil-inhabiting fungi belonging to the genus Verticillium , is found on a number of hardwood hosts. In southern and eastern United States elms and maples are attacked throughout their natural ranges. Wilting foliage and defoliation of elms caused by Verticillium wilt. Infected trees may die within a few weeks after the first symptoms are observed, or they may survive for years. The first symptoms of the disease involve a wilting of the foliage, with the leaves

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ARMILLARIA ROOT AND BUTT ROT

Mushroom or fruiting bodies of the “honey mushroom” rot. Armillaria root and butt rot is caused by the fungus Armillaria mellea . This disease is common in orchards, vineyards, gardens, parks, and forests throughout the world. Both coniferous and hardwood forest trees are attacked. The fungus is especially troublesome in plantations, particularly in stands recently thinned. The fungus is spread by spores produced by honey-colored mushrooms, rhizomorphs, and root contacts between diseased trees o

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CYLINDROCLADIUM ROOT ROT

This nursery disease is caused by two fungi species. Cylindrocladium scoparium and C. floridanum : Cylindrocladium root rot has been found on two hardwoods (yellow-poplar and black walnut) and two conifers (white pine and Fraser fir) in forest tree nurseries in six southern states. These include Virginia, West Virginia, North Carolina, Tennessee, Alabama, and Mississippi. Leaf symptoms on 1-0 black walnut nursery stock. Root rot symptoms on hardwoods and conifers are quite different. The most ch

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LUCIDUS ROOT AND BUTT ROT

Fruiting body of Lucidus root and butt rot on mimosa. Polyporus lucidus is the cause of root and basal stem decay of hardwood trees throughout the eastern, central, and southern portions of the United States. The fungus is known to attack and kill maple, hackberry, orange, lemon, ash, sweetgum, oak, locust, elm, tupelo, willow, and mimosa. Mimosa trees are very susceptible to attack by P. lucidus throughout the South. The disease is characterized by a rapid decline and death of the host. Examina

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