CAUTION

Pesticides used improperly can be injurious to humans, animals, and plants. Follow the directions and heed all precautions on the labels. Store pesticides in original containers under lock and key- out of the reach of children and animal-and away from food and feed. Apply pesticides so that they do not endanger humans, livestock, crops, beneficial insects, fish, and wildlife. Do not apply pesticides when there is danger of drift, when honeybees or other pollinating insects are visiting plants, or in ways that may contaminate water or leave illegal residues. Avoid prolonged inhalation of pesticide sprays or dusts; wear protective clothing and equipment if specified on the container. If your hands become contaminated with a pesticide, do not eat or drink until you have washed. In case a pesticide is swallowed or gets in the eyes, follow the hrst-aid treatment given on the label, and get prompt medical attention. If a pesticide is spilled on your skin or clothing, remove clothing immediately and wash skin thoroughly. Do not clean spray equipment or dump excess spray materials near ponds, streams, or wells. Because it is difficult to remove all traces of herbicide from equipment, do not use the same equipment for insecticides or fungicides that you use for herbicides. Dispose of empty pesticide containers promptly. Have them buried in an approved sanitary landfill. NOTE: Some States have restrictions on the use of certain pesticides. Check your State and local regulations. Also, because registrations of pesticides are under constant review by the Federal Environmental Protection Agency, consult your county agricultural agent or State extension specialist to ensure the product is still registered for use.

April 1999

Southern Research Station P.O. Box 2680 Asheville, NC 28802 CONTENTS

INTRODUCTION ...... 1 FOLIAGE INSECTS ...... 4 Sycamore Tussock Moth ...... 4 Whitemarked Tussock Moth ...... 5 Fall Webworm ...... 6 Leaffolders and Webworms ...... 7 Case-Bearing Leaf Beetle ...... 8 Sycamore Lace Bug ...... 9 Leafhoppers ...... 10 MINOR FOLIAGE INSECTS . . . . . 11 Sycamore Leafblotch Miner ...... 11 Drab Prominent ...... 11 Japanese Beetle ...... 12 Sycamore Plant Bug ...... 12 SEEDLING, TERMINAL, AND BRANCH INSECTS . 13 Planthoppers ...... 13 Scale Insects ...... 14 Stalk Borer ...... 15 European Corn Borer ...... 16 TRUNK BORERS ...... 17 Columbian Timber Beetle ...... 17 Flatheaded Borers ...... 18 MINOR TRUNK BORERS ...... 19 Ambrosia Beetles ...... 19 American Plum Borer ...... 19 ROOT INSECTS ...... 20 Whitefringed Beetles ...... 20 SEEDLING DISEASES ...... 21 Cylindrocladium Root Rot ...... 21 FOLIAGE DISEASES ...... 22 Anthracnose-LeafBlight ...... 22 Powdery Mildews ...... 23 Bacterial Leaf Scorch ...... 24 Minor Leaf Spots and Blights ...... 2.5 WILT, DECLINE, AND DIEBACK . . . . 26 Acremonium Wilt ...... 26 Sycamore Decline and Dieback ...... 26 CANKERS ...... 28 Canker Stain ...... 28 Botryosphaeria Canker ...... 30 Anthracnose-Twig Canker and Shoot Blight ...... 31 Hypoxylon Canker ...... 32 Miscellaneous Cankers ...... 33 ROOT AND BUTT ROTS ...... 34 Armillaria Root Rot ...... 34 Hericium Butt Rot ...... 35 Oxyporus Root Rot ...... 36 Ganoderma Butt Rot ...... 37 Scytinostroma Root Rot ...... 38 PARASITIC PLANTS ...... 39 Mistletoe ...... 39 AIR POLLUTION AND CHEMICAL INJURIBS ...... 40 MAINTAINING TREE HEALTH ...... 41 ACKNOWLEDGMENTS ...... 43 GLOSSARY ...... 44

ii A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury of Sycamore

T.D. Leininger, J.D. Solomon, A.D. Wilson, and N.M. Schiff

Abstract

This booklet will help nurserymen, forest woodland managers, pest control operators, and homeowners to identify and control pest problems on sycamore trees. The major insect and disease pests of sycamores in the Eastern United States are emphasized. Descriptions and illustrations of the pests and the damage they cause are provided to aid in identification. Brief notes are given on biology and control to aid in predicting damage and making control decisions.

Keywords: Bacteria, biology, borers, control, defoliators, fungi, identification, Platanus.

INTRODUCTION

Sycamore (Platanus occidentalis Mexico and southern Ontario. Sy- L.) is a common tree and one of the camore is often a pioneer species on largest in eastern deciduous forests. river fronts, upland old-field sites, and Other names are American sycamore, on strip-mined coal lands. However, American planetree, buttonwood, and it grows best and biggest on sandy buttonball-tree. Its native range in- loam soils with a good ground water eludes the area east of the Great Plains supply, typically on alluvial sites from south-central Texas and eastern along rivers and in bottomlands. Sy- Nebraska eastward to Maine and camore timber is valued for both lum- Florida. However, sycamore is ber and pulp and is also planted planted as an ornamental in many widely as a shade tree because of its Western States, especially California. broad, dense crown, exfoliating bark It is also found in northeastern on mature stems, and distinctive thin,

T.D. Leininger and A.D. Wilson are the Principal Research Plant Pathologists, J.D. Solomon is the Prin- cipal Research Entomologist, Emeritus, and N.M. Schiff is a Research Entomologist at the Southern Hardwoods Laboratory, U.S. Department of Agriculture, Forest Service, Southern Research Station, Stoneville, MS 38776; in cooperation with: Mississippi Agricultural and Forestry Experiment Station and the Southern Hardwood Forest Research Group. green to greenish-white bark on scaf- Sycamore production usually suf- fold branches and young stems. Eas- fers more from diseases than from ily propagated from seeds or cuttings, insects. In some years, leaf diseases and second only to cottonwood in can defoliate trees or entire stands, growth rate, sycamore lends itself reducing radial and terminal growth well to artificial regeneration and in- and weakening trees, making them tensive culture. It is among only a few susceptible to other pathogens and hardwood species used to establish insect pests. Canker diseases, the most commercial plantations, an effort that damaging type of sycamore diseases, typically requires intensive site prepa- can cause branch dieback, top die- ration, early weed control (cultivation back, and bole cankers. Dieback and or herbicides or both), fertilization, mortality caused by canker diseases, and, in some cases, irrigation. Some along with other factors, have been plantations have been established at so serious in some plantations that a very close spacing and are being re- few timber companies in parts of the generated from coppice on short ro- South have sycamore planting “on tations to maximize fiber production. hold” until disease-control methods This kind of culture has been termed can be developed. “short-rotation forestry,” “silvicul- Cultural practices that maintain tural biomass farming,” or “fiber and promote tree health help mini- farming.” mize losses caused by pathogens and Insects, diseases, pollutants, and insects. It is better to prevent attack chemicals present continuous threats by pathogens and insects than to rem- to sycamore growth and production. edy the aftermath of an attack. Some Many insects feed on sycamore, but recommendations are provided in the few actually cause serious injury. Ter- back of this guide under “Maintain- minal-feeding insects can sometimes ing Tree Health.” Chemical or other cause serious seedling mortality and direct controls may be needed as a last misshaped stem form. Insect defolia- resort. tors, perhaps the most common pests, This guide will help nursery may strip entire trees or stands in lo- workers, forest managers, insect-pest calized areas, weakening trees and and disease-control specialists, and causing growth loss. However, those homeowners to identify and control pests seldom cause significant mor- insect pests and diseases of sycamore tality. Insect borers rarely occur in trees. It emphasizes major diseases large populations except in stressed and insect pests in the Eastern United or weakened trees and in transplanted States and includes descriptions and ornamentals. Timber beetles some- illustrations of pathogens and insects, times seriously degrade sawtimber as well as the damage they cause. To and sawlogs. aid in assessing the risk of further

2 damage and making control decisions, root rot. For simplicity, we have omit- brief notes describe the biology and ted the words “caused by” between control of pathogens and insects. each disease name and its respective We have described pathogens and pathogen name. insects both with common names and Specific chemical controls are not Latin binomials, including taxonomic listed because recommendations authorities. However, a distinction change whenever compounds are dis- must be made between the treatment continued or new materials are ap- of disease and pathogen nomenclature proved. For information on pesticides and that of insects. The common or additional assistance with manag- name of an insect refers to the insect ing sycamore pests, the landowner itself. The common name of a disease should contact his or her county ex- typically includes the latin name for tension agent, State Forester, or the the genus of the pathogen causing the nearest office of the U.S. Department disease. For example, the fungal of Agriculture, Forest Service, State pathogen Cylindrocladium scoparium and Private Forestry, Forest Health causes the disease Cylindrocladium Protection.

3 FOLIAGE INSECTS

Sycamore Tussock Moth, Walsh

Importance.-This insect feeds on Biology.-Moths emerge from over- sycamore leaves throughout the Eastern wintering cocoons during May and June United States. It is more likely to defoli- and deposit egg masses on the underside ate older plantations, seed orchards, and of leaves and on bark. Eggs hatch in late ornamental plantings than nurseries and May and June. Young larvae feed close young plantations. Repeated late-summer together; older larvae scatter and become defoliation reduces growth and vigor. solitary feeders. Pupation occurs in late Identifying the Insect (fig. la, b).- June and July in hairy, ball-like cocoons Larvae have orangish heads and yellow- on bark and nearby debris. Moths emerge ish bodies covered with hair. Caterpillars in July and August to produce a second (30 mm long) exhibit long hair pencils- generation. These larvae spin cocoons and two pairs of orange and 2 pairs of white pupate in late September and October to hair pencils anteriorly, and one pair of overwinter. white hair pencils posteriorly. Moths are Control.-Natural enemies control pale yellow with darker bands on forew- most populations. The control of brush ings. and debris in and around plantings will Identifying the Injury (fig. lc).- reduce the best pupation sites. Chemical Young larvae skeletonize the leaves, feed- controls may be needed. ing together on the leaf’s underside. Older larvae devour all but the major leaf veins.

Figure l-(a) Sycamore tussock moth, (b) larva and feeding injury; (c) young plantation sycamore defoliated. Whitemarked ‘lbssock Moth, Orgyia leucostigma (J. E. Smith)

Importance.-This tussock moth de- consume leaf patches, eventually foliates a wide variety of trees, but the consuming all but the leaf’s midrib and sycamore is among its preferred hosts. It main veins. Late-summer defoliation by occurs throughout the Eastern United large populations may cause a States and Southern Canada. Heavy de- skeletonlike appearance to entire trees as foliation causes growth loss and dieback well as entire stands. but rarely kills trees. Biology. - Overwintering eggs hatch Identifying the Insect (fig. 2a, b).- from April to June. Newly hatched lar- The yellowish, hairy larva (30 mm long) vae feed close together but often are dis- has a coral-red head and thoracic shield persed on silken threads by wind. Lar- with a black dorsal stripe. Four yellow- vae mature in 5 to 7 weeks and spin gray- ish, brushlike hair tufts occur dorsally. A ish, hairy cocoons on the underside of pair of black hair pencils arises anteriorly, branches and in bark crevices. The pu- and a single hair pencil arises posteriorly. pal stage lasts 2 weeks. Females deposit Male moths are gray with dark wavy 50 to 300 eggs in masses usually on or bands on the forewings. Females have no near the old cocoons. There are one to wings. Eggs are deposited in flattened three generations per year. Egg masses clusters covered with whitish, frothy ma- overwinter on host plants. terial. Control.-Populations on small trees Identifying the Injury (fig. 2c).- can be controlled by destroying the con- Young larvae skeletonize the undersides spicuous, whitish egg masses. Insecti- of leaves. Older larvae disperse and cides may be needed.

Figure 2-(a) Wingless female whitemarked tassock moth laying a mass of eggs; (b) larvae and feeding injury; (c) young trees defoliated. Fall Webworm, Hyphantriu culzea (Drury)

Importance.-The fall webworm de- but large tents may not be. Large groups foliates more than 100 deciduous tree spe- of feeding caterpillars can cause sparse cies across the United States and South- and ragged foliage over the entire crown. em Canada. Although seldom entirely de- Biology.-Moths emerge from over- foliated, infested sycamore trees may be wintering pupae from March to July and severely “ragged” causing premature leaf oviposit on the underside of leaves in drop and reduced growth and vigor. masses of 300 to 500 eggs, that hatch in Identifying the Insect (fig. 3a, b).- 10 days. Distinct silken tents often do not There are two races of H. cunea- occur on sycamore trees. Larvae may be blackheaded and redheaded. Larvae of present from April to October, but the both are pale yellowish with a broad, greatest numbers occur in late summer dusky dorsal stripe and yellowish lateral and fall. Pupation occurs in thin cocoons stripes. Covered with gray hair, the lar- near the soil surface. There are one to vae are about 25 mm long. Moths are pure four generations per year, depending on white to white with small dark spots. The locale and race. tiny gray eggs are in large masses partially Control.-More than 80 natural en- covered with short grayish hairs. emies are known. For young trees, it is Identifying the Injury (fig. 3c).- possible to control the insect by clipping Typically, large silken webs enclose one and destroying the webbed branches while or more leaves and, eventually, entire the larvae are small. Insecticides may be branches in summer and fall. In sycamore required. plantations, however, webbing is present,

Figure 3-(a) Fall webworm egg mass on underside of leaf, (b) larvae feeding under webbing; (c) partially defoliated sycamore with little webbing.

6 Leaffolders and Webworms, Ancylis platanana (Clemens), Pococera militella (Zeller), Adoxophyes jiucatana (walker)

Importance.-A complex of leaf- often leaving only a brown network of the folding and web-making larvae feed on larger veins. Injury by other webworms sycamore leaves. Ancylis platanana, oc- is similar but with more extensive web- curring only on Platanus throughout the bing. Eastern United States, is emphasized Biology.-Adults of A. platanana here. Heavy defoliation of small groups emerge from March to May and deposit of trees may occur. Repeated defoliation eggs singly on the undersides of leaves. may reduce growth and incite crown die- Eggs hatch in 3 to 5 days, and the young back. larvae feed along the leaf midrib. Older Identifying the Insect (fig. 4a).- larvae pull the leaf over into a fold and Larvae of A. platanana are slender and feed for about 6 weeks until they pupate pale yellow with smooth bodies; mature beneath the webbing in the folded leaf. larvae are 9 to 11 mm long. The forew- The pupal stage lasts 9 to 11 days before ings of adults are reddish with white the adults emerge. There are three to four markings. Eggs are small, oval, and al- generations per year. Overwintering oc- most colorless. curs as prepupae in fallen leaves. Identifying the Injury (fig. 4b, c>.- Control.-Natural enemies help con- Small, silken shelters are found on the trol populations. Some control is possible undersurface of partially skeletonized by disking to bury fallen leaves and pu- leaves. A leaf gradually becomes folded pae. and is further webbed and skeletonized,

Figure 4-(a) Leaffolder larvae and early-season feeding at base of leaf; (b) advanced feeding and extensive webbing; (c) heavy defoliation. Case-Bearing Leaf Beetle, Neochlumisus platani (Brown)

Importance.-This beetle is known larvae are found feeding on young foliage. from Massachusetts west to Colorado and Small, scattered holes appear in the leaf. south to Florida and Texas. It feeds on In time, the holes are enlarged and, sycamore foliage and prefers young trees. typically, uniformly distributed over the Defoliation may result in loss of growth leaf surface. Trees may appear “ragged” and aesthetic value, but no crown dieback from heavy leaf feeding but are seldom or mortality has been associated with this completely defoliated. insect. Biology.-Overwintering beetles ap- Identifying the Insect (fig. 5a, b).- pear on the foliage of host trees in April Adults are peculiarly shaped leaf beetles and May. Females lay tiny, bell-shaped, with a rough, knobby, brownish body sur- excrement-covered eggs singly and on face, 4 to 5 mm long, resembling the short stalks on the undersides of leaves. brown excrement pellets of large cater- Young larvae construct and live within pillars. When disturbed, beetles feign cases made of their own frass. Pupation death and fall from the plants. Larvae are occurs within the case attached to the un- white with black heads and legs, 5.4 to derside of a leaf. Highest populations oc- 6.5 mm long, and live in dark-brown cur in early summer. Only one or two gen- cases made of fecal excreta, which con- erations occur per year. ceal all but the head and legs. Control.-Parasites and predators Identifying the Injury (fig. 5c, d).- usually keep populations under control. Both adult beetles and case-bearing

Figure 5-(a) Larval case; (b) larva removed from case; (c) close-up of feeding damage; (d) tree with feeding injury.

8 Sycamore Lace Bug, Cqthucha ciliatu (Say)

Importance.--One of the most com- excrement and shed skins. Large mon insects found on sycamore foliage, populations of lace bugs may cause leaves lace bugs may occur in large numbers on to turn brown and drop prematurely. shade or ornamental trees in urban areas, Biology.-Adults overwinter under especially in late summer or during dry bark and become active when leaves start periods. Corythucha ciliata is a problem to develop. Eggs are glued to the pubes- throughout the Eastern United States. cence on the undersides of leaves. Both Identifying the Insect (fig. 6a, b).- adults and nymphs feed on the undersides The adult is a pale, flattened insect about of leaves by sucking sap with piercing 3 mm long whose wing covers are ex- mouthparts. Nymphs seldom move to an- tended and so intricately ornamented that other leaf until they are almost mature. they appear to be made of a piece of lace. The complete life cycle from egg to adult Immatures are also flattened but are black takes about 30 days, and there may be 2 and covered with spines. to 5 or more generations per year. Late in Identifying the Injury.-The lace the year, synchrony of generations breaks bug pierces the epidermis and withdraws down, and all life stages may be found on fluids and cell contents, which results in the same leaves. chlorotic flecking on the upper surface of Control.-Predators usually keep leaves. Late in the growing season the lace bug populations small. Chemical leaf’s lower surfaces may appear messy, control may be required in late summer having been varnished with lacebug and fall when populations are largest.

Figure 6-(a) Adult lace bugs feeding on underside of leaf; (b) lace bug nymphs feeding on underside of leaf.

9 Leafhoppers, Erythroneura Zawsoni Robinson, E. arta Olivier, E. usitata Beamer

Importance.-Although many spe- chlorotic, especially around the midrib cies of leafhoppers may be found on sy- and basal veins. Large populations of camore foliage, the three listed species of leafhoppers may be present on the Erythroneura cause most infestations. undersides of leaves. Heavy infestations Leafhoppers suck the leaf sap, reducing result in poor leaf color, premature leaf tree vigor, and may transmit viruses and drop, and a less pleasing appearance. mycoplasma diseases. Biology.-After overwintering in leaf Identifying the Insect (fig. 7a).- litter and debris, adult leafhoppers be- Leafhopper adults are small (6 mm), lin- come active on newly opened sycamore ear insects that appear tapered at both buds. Mating and egg laying start early in ends. They vary from yellowish to light the growing season. An average genera- green with some speckling or striping. tion matures in 41 days. In the late fall, Leafhoppers jump or shoot away when adults move to protected sites to overwin- disturbed, earning them the nickname ter. sharpshooters. Immatures have a similar Control.-Leafhoppers are controlled shape but are smaller, wingless, and paler by spiders, wasps, fungal diseases, and in color with the ability to run backwards abiotic factors such as rainfall and wind. on the leaf. Chemical control may be needed for Identifying the Injury (fig. 7b).- ornamental trees during summer and Injured leaves become stippled and fall.

Figure 7-(a) Leafhopper adults feeding on underside of leaf: (b) chlorotic stippling from feeding injury (top leaf), healthy leaf (bottom).

10 MINOR FOLIAGE INSECTS

Sycamore Leafhlotch Miner, Ectoedemiu plutunellu (Clemens)

Leafblotch miner larvae are pale green, slightly flattened with a retracted head, up to 4 mm long, living singly within dis- tinct leaf mines. The tiny adult moth is seldom seen, but it ranges over much of the Eastern United States. Ectoedemia leaf injury appears as a brown, circular blotch mine (+ 1 cm diameter) just below the leaf cuticle. Mines originate from a narrow entrance mine and are filled with frass in the center (fig. 8). Heavily mined leaves drop prematurely. Injury is un- sightly, but its impact on tree health usu- ally is slight to negligible. Natural en- emies control most populations. Direct controls are rarely needed. Figure 8Sycamore leaf with brown mines of E. platanella.

Drab Prominent, Misogadu unicolor (Packard) Drab prominent larvae are light green with a broad, yellowish-white dorsal stripe (with brownish patches) and narrow in- distinct lines on each side. A pair of tail- like projections is borne on the last ab- dominal segment. Mature larvae are 30 to 42 mm long (fig. 9) and may be present from April to September. Young larvae feed close together and skeletonize the undersides of leaves. Large larvae be- come solitary feeders and will devour all but a leaf’s major veins. There are two to three generations per year. Parasites keep most populations in check.

Figure 9-Fully grown larva of 44. unicolor. Japanese Beetle, Popillia japonica Newman

Japanese beetles are broadly oval, 12 mm long, metallic green and coppery, with small tufts of white hair both behind and on each side of the elytra (fig. 10). Preva- lent in some Atlantic Coast States, they emerge from May to July and live for 30 to 45 days. They feed on over 300 plant species and devour sycamore leaf tissue between the veins, commonly leaving only a lacelike network of veins. They may completely defoliate seedlings and young trees. A milky disease bacterium, Bacilluspopilliae Dutky, is commercially available to control the larval stage in the soil. Chemical control of adults may be needed. Figure l&Japanese beetle (inset) and feeding injury to leaves.

Sycamore Plant Bug, Plagiognathus albatus (Van Duzee) Adults are pale yellowish, elongated soft- bodied true bugs, 3 to 5 mm long, with piercing-sucking mouthparts (fig. 11). Nymphs resemble the adults but are wing- less. These bugs occur over much of East- em North America. Overwintering eggs, embedded in twig tissue below leaf buds, hatch in April. Nymphs and adults (both present until July) feed on tender leaves, causing tiny irregular brown spots that often fall out, leaving a ragged and tat- tered leaf (fig. 11). There is one genera- tion per year. Direct controls may be needed to protect high-value trees.

Figure 1 l-Adult of P. albatus (inset) and injury to foliage.

12 SEEDLING, TERMINAL, AND BRANCH INSECTS

Planthoppers, Ormenoides venusta (Melichar), Anormenis septentrionalis (Spinola)

Importance.-Planthoppers feed on However, large clusters of oviposition sycamore and many other species punctures along the stems may cause seed- throughout the Eastern United States and ling mortality as well as terminal dieback as far West as Texas and Arizona. Their in older plants. Young seedlings planted sap feeding and oviposition injuries some- adjacent to natural stands are most prone times cause serious damage to seedlings to injury. and the terminals of older plants. Biology.-Eggs overwinter inside Identifying the Insects (fig. 12a).- twigs of host plants and hatch in the Adults are snow white to pale green and spring. The nymphs feed in clusters on have large prominent wings held at an succulent shoots. Adults begin appearing acute, rooflike angle over the body. They in June and are present until fall. Females range from 6 to 12 mm long. Nymphs are deposit their eggs in short slits in the bark white or greenish, wingless, slightly flat- of the current year’s growth. There is one tened with abdomen curved slightly up- generation per year. ward, and are partially covered with fila- Control.-Shoots containing clusters ments of white, wool-like wax. of oviposition punctures can be pruned Identifying the Injury (fig. 12b).- and destroyed in fall and winter, although Sap feeding by large populations may natural enemies keep most populations in cause succulent shoots to wilt and grow check. more slowly but seldom causes dieback.

Figure 12-(a) Planthopper adults feeding on a young sycamore stem; (b) a young sycamore terminal killed by punctures of egg-laying adults.

13 Scale Insects, Terrapin scale, Mesokcanium nigrufusciutum (Pergande); Cottony maple scale, Puluinariu innumerubilis (Rathvon); European fruit lecanium, Parthenolecanium corni (Boucht); Oystershell scale, Lepidosuphes ulmi (L.)

Importance.-Scale insects reduce Oystershell scale females look like tiny plant vigor and may cause faded areas in (3 mm long), chestnut-brown oyster affected leaves, premature leaf drop, and shells. In large numbers they form a even twig mortality. They produce hon- “crust” on trunks and branches. eydew, which supports the growth of Identifying the Injury.-Injury may sooty molds that block photosynthesis. appear as yellow spots on leaves, necrotic Injuries detract from the appearance and areas, dieback, shiny leaves, growth of value of the tree. These insects occur black sooty mold, or leaf drop. Scales can throughout the United States. be found by examining the bark. Identifying the Insect. -Terrapin Biology.-Scale insect life cycles are scale females appear as oval-shaped, red- complicated with large, somewhat seden- dish-brown, shiny bumps (2 mm across) tary females and relatively small, winged on branches (fig. 13a). Cottony maple males. There may be several generations scale females look like small powdery per year. Overwintering is typically on popcorn kernels with a dark shell (4 to 6 branches or under bark. mm) trailing a large cottony white egg sac Control.-Parasites and predators (fig. 13b). European fruit lecanium fe- usually keep scales under control. Occa- males are distinctly humped (3 to 6 mm), sional chemical treatment of ornamental dark brown to reddish, and sometimes plants may be useful. covered with whitish powder (fig. 13~).

Figure 13-(a) Terrapin scale; (b: I cottony maple scale; (c) European fruit lecanium. Stalk Borer, Papaipema nebris (Guenee)

Importance.-The stalk borer is entrance holes occur in late spring. widely distributed throughout the Eastern Excrement pellets often are present at United States and Canada. It attacks over entrance holes. Opening the shoot will 175 herbaceous and woody plant species. reveal a tunnel and larva. Corn, grasses, and giant ragweed are fa- Biology.-Overwintering eggs hatch vored hosts. However, succulent sy- from April to June. Young larvae feed on camore shoots are killed occasionally in grasses; older larvae seek larger, succu- nurseries and young plantations. lent stems and often migrate from herba- Identifying the Insect (fig. 14a, b).- ceous plants to young sycamore trees. Larvae have broad stripes of pale white Larval development varies from 60 to 130 and brown interrupted by a distinct band days. Mature larvae abandon their hosts of purplish brown around the third tho- and pupate just below the soil surface. racic and first abdominal segments. Ma- Moths emerge from August to October ture larvae are 25 to 32 mm long. Adults and deposit up to 2,000 eggs each on are robust moths; their forewings are pur- grasses where they overwinter. There is plish brown with several small white one generation per year. spots. Eggs are globular and whitish Control.-Damage can be minimized brown. by disking weedy borders of nurseries and Identifying the Injury (fig. 14c).- young plantations to destroy breeding Sudden wilting and flagging of succulent sites in early August. Direct controls may shoots with 3-mm-diameter round be needed.

Figure 14--(a) Stalk borer adult; (b) larva tunneling in young shoot; (c) terminal being killed by larval tunneling, gallery entrance near apex. European Corn Borer, Ostriniu nubildis (Htibner)

Importance.-This pest of corn and are found in tender shoots. Splitting the over 100 other plants sometimes infests infested shoot will reveal a tunnel, frass, sycamore trees in the Eastern United and a gray larva. States. Typically, trees are attacked only Biology.-Overwintering larvae pu- when growing near heavily infested pre- pate in April and May, and moths emerge ferred hosts such as corn and certain cover from May to June. Females deposit 500 crops. In sycamore nurseries, the Euro- to 600 eggs on herbaceous hosts that hatch pean corn borer may tunnel through and in a week. Larvae complete feeding in kill up to 30 percent of the terminals. July, and moths emerge in August. Sec- Identifying the Insect (fig. 15a).- ond generation larvae feed until fall and Larvae have brownish mottled heads and overwinter in their tunnels. There may be grayish bodies with pinkish-brown stripes one to two generations per year. Infesta- and are about 25 mm long. Adult moths tion of sycamore tree typically occurs are brownish with yellowish-brown when heavily infested herbaceous hosts forewings that are somewhat streaked. mature or are harvested, causing the lar- Eggs are oval and yellowish white. vae to migrate to other succulent hosts. Identifying the Injury (fig. 15b, c).- Control.-Preferred crops like corn The first sign of infestation is rapid wilt- or millet should not be planted next to ing and dying of seedling terminals and sycamore nurseries. Chemical controls branch tips. Holes 4 to 6 mm in diameter may be required.

Figure 15--(a) Larvae of 0. nubildis; (b) terminal being killed by larval tunneling; (c) young stems with entrance holes, frass, and tunnel.

16 TRUNK BORERS Colombian Timber Beetle, Corthylus columbianus Hopkins

Importance.-The Columbian timber in log ends are evidence of damage in beetle occurs from Massachusetts south sawlogs. In lumber and veneer, defects to Florida and west to Kansas. Beetles consist of small, black, round holes sur- bore into the trunks of trees of all sizes. rounded by elongated brown stains. Beetle attacks do not seem to affect tree Biology.-Adults overwinter in bark health directly, but they provide entry niches around the base of host trees. points for canker and other diseases. Dam- Beetles emerge in May and June and be- age can degrade the lumber by as much gin excavating brood galleries on host as 25 percent. trees. Completed galleries consist of pri- Identifying the Insect (fig. 16a).- mary, secondary, and tertiary channels Adults are 3.6 to 4.0 mm long, reddish with 1 to 20 brood cells (cradles). Eggs brown to black, cylindrical ambrosia are deposited singly in each brood cell. beetles. Eggs are white, translucent, shiny, Both larvae and adults feed on ambrosia and oval. Larvae are white, legless, C- fungi that grow on gallery walls. Brood shaped, and about 4 mm long. emergence occurs in 6 to 7 weeks. There Identifying the Injury (fig. 16b, c).- are two to three generations per year. Sap and fine frass oozing out of small Control.-Few natural enemies have round entrance holes in the trunk are evi- been identified, and no direct controls dence of injury. Radiating brown stains have been developed.

Figure l&-(a) Adult of C. columbianus; (b) tiny entrance hole with frass and stain; (c) stained flagworm defects in lumber. Flatheaded Borers, Flatheaded appletree borer, Chrysobothris femorata (Olivier); Pacific flatheaded borer, C. maZi (Horn)

Importance.-These borers are the bark. Tunnels under the bark are widely distributed: C. femorata, through- broad, irregular, and packed with powdery out the United States into Canada and frass. The bark of infested trees may be Mexico; and C. mali, through the West- heavily scarred by larval burrows and em States. They make extensive galleries oval exit holes of emerging beetles. under the bark and often girdle and kill Biology.-Adults begin emerging in newly transplanted trees. March and are present until fall. Females Identifying the Insects (fig. 17a, deposit about 100 eggs each in small b).-Larvae are yellowish white, legless, groups in bark crevices. Eggs hatch in 8 and 18 to 25 mm long. The thoracic seg- to 16 days. Larvae feed in the cambium ments are broadened, which gives the until late summer, then tunnel radially into appearance of large, flat heads. Adults are the sapwood to overwinter. In spring, the flattened, metallic-hued beetles (7 to 16 larvae pupate for 8 to 14 days before the mm long), marked with gray spots in C. adults emerge. Generation time varies femorata and coppery spots in C. mali. from 1 to 2 years. Eggs are yellowish white, flattened and Control.-Cultural practices that pro- disclike. mote tree vigor help minimize attacks. Identifying the Injury (fig. 17c).- Weakened and dying trees should be re- White, frothy sap oozes from cracks in moved to eliminate breeding sites.

Figure 17-(a) Adult of C. femoruta; (b) bark removed to expose larva; (c) larval burrow in bark.

18 MINOR TRUNK BORERS

Ambrosia Beetles, Xylosandrus spp., Xyleborus spp., Platypus spp.

Some ambrosia beetles attack healthy trees, but most prefer weakened, injured, or dying trees and fresh-cut logs (fig. 18). They bore into the sapwood and reduce tree and log values for wood products; some spread fungal pathogens. Larvae feed on a moldy fungus called ambrosia that adult females culture on the gallery walls. Small piles of boring dust or strings of compacted frass may be present on the bark. There are two or more generations per year. Adults can be trapped with pheromones. Logs should be processed promptly.

Figure 18-Adult of l? compositus (inset) and strings of frass.

American Plum Borer, Euzophera semifuneralis (Walker)

Larvae vary from dark pink or reddish gray to dusky green, with a dark-brown head and thoracic shield. They are about 25 mm long when full grown (fig. 19). The American plum borer is widely dis- tributed throughout the United States, Canada, and parts of Mexico. Weepy sap spots appear on the bark, followed by accumulations of reddish frass in bark crevices (fig. 19). Lifting the bark will expose larval burrows, frass, larvae, and white, silken cocoons. This borer prefers trees in poor health, especially those with mechanical injuries to the bark and can- ker diseases. Good cultural practices help minimize infestation. Direct controls may Figure 19-Larva of E. semifunerulis (inset), be needed to protect valuable trees. frass, and burrows. ROOT INSECTS

Whitefringed Beetles, (Boheman), G. minor (Buchanan), G. peregrinus (Buchanan), and G. fecundus Buchanan

Importance.-Whitefringed beetles may die; injured survivors appear yellow were introduced into Florida in 1936 and and unhealthy. Excavation will reveal root have spread north to Virginia and west to injury. Larvae can be found in the top 12 Louisiana. They feed on over 300 plant to 24 cm of soil. Adults may be seen rest- species. On young sycamore trees, the ing around the bases of plants. larvae destroy both tap and lateral roots. Biology.-Overwintering larvae be- Damage may occur in new nurseries and gin pupating in April, and adults emerge first-year plantations established on sites from May to October. All adults are fe- with heavier soils not well suited for sy- males, each of which deposits up to 1,500 camore production. eggs in the soil in masses of 11 to 14. Eggs Identifying the Insects (fig. 20a, hatch in 11 to 30 days, and larvae feed on b).-Adults are dark-gray, 9-mm-long plant roots. There is one generation per beetles with a white fringe along the outer year. Adults cannot fly, but the insect is margins. Full-grown larvae are yellowish easily spread by moving infested plants, white, C-shaped, legless, and 12 mm long soil, or equipment. with a pale head. Eggs are oval and pale Control.-Commercial traps are yellow. available to monitor infestations. Fallow- Identifying the Injury. (fig. 2Oc).- ing heavily infested soils will reduce Damaged plants become chlorotic and populations.

Figure 2&(a) Whitefringed beetle; (b) larvae; (c) larval feeding injury to roots of sycamore seedling. SEEDLING DISEASES

Cylindrocladium Root Rot, Morg.

Importance.-Sycamore seedlings appear on surface lesions. Yellow-orange and other southern hardwood species are perithecia (0.4 mm) may form on dead susceptible to Cylindrocladium root rot, leaves and bark under moist conditions. especially in nurseries where seedlings are Biology.--Conidia produced on stem grown close together (fig. 21a). and leaf lesions are spread by wind and Identifying the Disease.-Infected splashing rain to other susceptible seed- seedlings may be killed by this disease or lings. Microsclerotia released into the soil will exhibit a combination of symptoms: may survive for years, and, during moist damping-off, root rot, hypocotyl rot, leaf conditions, germinate to infect roots. spots, leaf blight, stem lesions, twig die- Control.-To prevent spread of in- back, and wilting. Affected roots turn oculum and minimize conditions that fa- black, shrivel, and die (fig. 21b). vor the fungus, avoid overhead watering Aboveground symptoms are favored by in the summer. Plant seedlings further warm, moist conditions such as those that apart to promote vigorous growth and re- exist during summer irrigation by over- duce seedling susceptibility. Remove dis- head sprinklers. eased seedlings, and improve soil drain- Identifying the Fungus.-The fun- age on moist sites. High-hazard sites may gus produces pinpoint-sized, brown require soil fumigation in the fall or spring microsclerotia on dead roots, leaves, and to reduce inoculum in the soil. stem lesions. Tiny white tufts of conidia

Figure 21-(a) Sycamore seedling survival in the center and right rows is poor due to root rot, compared to that of the two rows on the left.

(b) Sycamore seedlings with root damage (left), and normal roots (right). FOLIAGE DISEASES

Anthracnose-Leaf Blight, Apiognomonia (=Gnomonia) veneta (Sacc. & Speg.) H6hn. Importance.-(See p. 31, Anthra- grow along veins and the midrib into the cnose-Twig Canker and Shoot Blight). petiole and twig. Leaf infections are Identifying the Disease.-Anthrac- favored by cool (16-20 “C), wet weather. nose-blighted leaves have irregularly Repeated infections can occur throughout shaped, tan necrotic patches that run along the growing season under favorable the midrib and larger veins (fig. 22a). weather conditions, which, in the South, Necrotic patches often coalesce and span are common in the fall. the area between veins. Lesions also form Control.-Wet conditions favor foliar on petioles and along leaf margins. Re- infections. Sycamore in plantations may peated infections throughout the growing be protected by increasing the space be- season can cause severe defoliation (fig. tween rows to ensure air movement. Land- 22c). scape trees may be protected from initial Identifying the Fungus.-Colorless, infections by applying a contact fungicide one-celled conidia are produced in pin- when buds begin to swell and, again, 10 head-sized, cream-colored acervuli on the to 14 days later. Injections of systemic bottoms of diseased leaves along veins fungicides offer protection as well (fig. and the midrib. 22b). Disease resistant varieties should be Biology.--Conidia produced on fallen planted if possible. There is no practical leaves or on the bark of diseased twigs control for this disease in forests. germinate and infect new leaves as hyphae

Figure 22-(a) Tan, necrotic patches along main veins of a leaf; (b) a systemic fungicide protected the sycamore on the left for 3 years compared to the two trees on the right; (c) severe defoliation from a heavy anthracnose infection.

22 Powdery Mildews, Microsphaera penicillata (Wallr.:Fr.) LCv. or Phyllactinia guttata (Wallr.:Fr.) Lev.

Importance.-Powdery mildews are to 0.2 mm) with distinctive appendages common throughout the range of sy- that aid in identification. In warmer ar- camore trees and are most damaging on eas, cleistothecia may not form. younger, smaller trees in ornamental, nurs- Biology-Initial infections are from ery, or orchard settings. They do not cause spores that overwintered on fallen leaves significant damage in forests. or in buds. Infections begin on young Identifying the Disease.-These shoots and expanding leaves but rarely on fungi are named for the powdery white or, mature leaves. Conidia are spread on air as they age, gray mycelia they produce on currents and can germinate on dry plant upper and lower leaf surfaces (fig. 23a). surfaces. Disease buildup is favored by Infected leaves are often stunted, buck- warm, dry days and cool nights. led, or cupped (fig. 23b). Mycelial mats Control.-Because powdery mildews may entirely cover young leaves or may grow superficially on leaves, they are eas- occur as irregularly-shaped blotches (0.5 ily controlled on ornamental trees with to several cm) on larger leaves. organic contact fungicides or sulfur dust. Identifying the Fungi.-Young Disease occurrence may increase with mycelial mats will have only the conidial activities that stimulate or prolong the stage of the fungus, which produces col- occurrence of new growth; e.g., fertiliz- orless spores. Older colonies may have ing and cultivating. Control in forests usu- spherical, brown-black cleistothecia (0.1 ally is not needed.

Figure 23-(a) White and gray mycelial mats of powdery mildew fungus on leaves in foreground; uninfected leaves in background; (b) leaf distortion and cupping caused by powdery mildew.

23 Bacterial Leaf Scorch, Xylella fastidiosa Wells et al.

Importance.-Planted and wild Identifying the Bacterium.-XyZeZZa sycamores are probably affected fastidiosa can be identified with a micro- throughout the Southeast. Bacterial leaf scope. Otherwise, five to seven 2-cm-long scorch has been found in plantation sections of symptomatic leaf petioles, from sycamore in Virginia, Kentucky, Illinois, three branches per suspect tree, can be Georgia, North Carolina, South Carolina, submitted to a State cooperative exten- and Alabama and in the wild in sion lab for an ELISA test to determine if Mississippi, Louisiana, and Texas. The this bacterium is in the tissue. disease is becoming important as more is Biology.-Xylella fastidiosa occurs learned about its pathogenicity and only in xylem tissue where it blocks water distribution. conduction. The bacteria are transmitted Identifying the Disease.-Olive-drab from plant to plant by xylem sap-feeding leaves appear in midsummer. Leaves later insects such as treehoppers. Cold limits appear scorched as tissues along leaf mar- bacterial growth, but leaf scorch seems to gins and between veins turn brown (fig. be enhanced by hot, dry weather. 24a). Symptoms advance from older to Control.-Xylella fastidiosa has a younger leaves on a branch; scorched wide host range, which makes it hard to leaves curl upward and stay attached until control directly by removing other hosts, fall (fig. 24b). Leaf scorch appears first on or, indirectly, by trying to control insect one branch, or a group of branches in one vectors. Maintaining tree health by irri- part of the crown, and moves through the gating and fertilizing ornamental and plan- crown in later years. Branch dieback may tation trees may delay disease onset and be worsened by secondary infections of prolong the life of infected trees. such fungi as Botryosphaeria rhodina (p. 30). Bacterial leaf scorch may be mis- taken for anthracnose (p. 22), which mainly affects young leaves during cool, wet periods. In some plantations, branch dieback, progressive decline (p. 26), and death occur within 5 to 7 years.

Figure 24-(a) Variation in leaf scorching caused by the leaf scorch bacterium; (b) leaves look scorched and cup upwards; older leaves are affected before younger leaves. 24 Minor Leaf Spots and Blights, Mycosphaerella platanifolia (Cooke) EA. Wolf, M. stigmina-platani EA. Wolf, Septoria platanifolia Cooke in Revenel, and Phloeospora multimaculans Heald & EA. Wolf

Importance.-Leaf-spotting fungi are celled. The conidia of the Cercospora or generally of little importance to tree Stigmina stages are multiseptate. Pycnidia health. Severe infections that trigger early of P. multimaculans grow on the lower leaf abscission may have some effect on surfaces of leaves and produce colorless, growth, but the main consequence is to cylindrical, slightly curved conidia with the tree’s appearance. one to four’ septations. Identifying the Disease.-Myco- Biology.-Initial infections of sphaerella platanifolia and M. stigmina- Mycosphaerella, the sexual stage of the platani leaf spots appear as unevenly first two fungi, occur in early spring from round, tan spots (0.1 to 1 cm) with red- spores produced in fruiting bodies on brown halos that may coalesce into larger, fallen leaves. Subsequent infections oc- irregularly shaped lesions (fig. 25). Leaves cur as asexual conidia from the infected by P. multimaculans develop Cercospora or Stigmina stages are moved unevenly round or angular, brown to by wind or rain splashing. Conidia of S. purple spots (1 to 3 mm). Septoria platanifolia and P multimaculans are platanifolia produces brown, circular spread by wind and rain from pycnidia spots that later develop gray centers with that form on the leaf spots. dark halos. Spots typically develop on the Control.-Leaf spots typically do not upper surfaces of leaves. The lower sur- warrant control on ornamental or forest faces of leaves infected by M. stigmina- trees because they are of minor conse- platani may have a diffuse, sooty film. quence to tree health However, organic Identifying the Fungi.-Ascospores fungicides are sometimes used to control of both Mycosphaerella species are two- severe outbreaks.

Figure 25-Mycosphaerella leaf spots.

25 WILT, DECLINE, AND DIEBACK

Acremonium Wilt, Acremonium Sycamore Decline and Dieback, various (=Cephalosporium) diospyri (Crandall) causal agents W. Gams Importance.-Sycamore decline, Fungus.-Initial infections by sometimes called dieback, has been re- conidia likely occur through bark wounds ported since the 1950’s across the South- made by insects, animals, or storms. em United States. The recurrence of this Injury-Brown leaves appear on one problem has led some companies to cur- to several branches in spring. The disease tail or halt commercial plantations. develops progressively causing twig die- Identifying the Disease.-Sycamore back, defoliation, and pale-yellow, stunted decline typically appears as foliar necro- foliar regrowth (fig. 26). Acremonium wilt sis and branch dieback in tree crowns is favored by hot weather (2 30 “C). Wilted throughout a plantation (fig. 27a). Indi- sycamores are susceptible to infection by vidual crown symptoms include sparse B. rhodina (p. 30). foliage, dead branches, and scorched Control.-Acremonium wilt is leaves (fig. 27b, c). Similar symptoms can mainly a problem in urban areas of east be caused by canker fungi such as C. Texas. It has been controlled experimen- fimbriata$ platani (p. 28), B. rhodina (p. tally by spraying leaves and trunks with 30), and P scabra (p. 33), or the bacte- fungicides. rium X. fastidiosa (p. 24), which often is associated with sycamore decline. Identifying the Causal Agents.- The combination of environmental and biological agents contributing to sy- camore decline may vary. Soil type, seed source, weather (temperature and precipi- tation extremes), time of planting, and plant culture can affect or trigger decline events. Specific pathogens and insects that attack declining trees are described else- where in this guide. Biology.-Sycamore decline results from a combination of environmental and biological stresses and subsequent attacks by opportunistic pests. An abiotic factor, e.g., soil type or drought, will predispose a tree or stand of trees; and another abi- otic or biotic factor, e.g., freezing tem- peratures or insect defoliation, will trig- ger a decline that results in mortality from various diseases and insects. Control.-There is much to learn about sycamore decline. Planting clones with some disease resistance on sites that are well suited for sycamore and avoid- Figure 26-Sycamore tree with Acremonium ing unnecessary wounding may be the best wilt. way to prevent sycamore decline. ’

26 Figure 27-(a) Sycamore decline, expressed as leaf scorching, thin crowns, and branch dieback, in a S-year-old plantation in southern Alabama in August. Xylellu fastidiom and Botryosphaeria cankers were present in this stand; (b) Trees inside the stand in (a) showing branch dieback and sparsely foliated crowns; (c) dieback and epicormic branching in a 4-year-old plantation. Note the exposed, inactive canker, likely Botryosphaeria, on the tree at center.

27 CANKERS Canker Stain, Cerutocystisfimbriutu f. pkztuni (Ellis & Hal%) J.M. Walter

Importance.-Canker stain is a Identifying the Fungus.-Conidia deadly disease that occurs on sycamore are produced on initial infection sites and and London planetree from New York to in well-colonized tissue. Black perithecia Georgia and west to Missouri. It poses a with long (1 mm) necks produce hat- threat to natural stands and plantations shaped ascospores. Diseased sapwood has throughout the South. brown-black, wedge-shaped staining that Identifying the Disease.-Canker is evident in stem cross sections (fig. 28d). stain is hard to detect early in its devel- Biology.-Both spore types are sticky opment, especially under older, scaly bark and are spread by humans and insects. The (fig. 28a). It may not be noticed until fungus can infect even the smallest wound symptoms appear in the crown. Long, that exposes cambium or sapwood. purplish-black, lens-shaped cankers form Control.-To prevent spreading can- on stems and large branches. Cankers ker stain to healthy trees, tools used to expand laterally about 9 cm per year and prune diseased landscape trees should be lengthen up to 3 m per year. Growth fol- sprayed with a solution of rubbing alco- lows the wood grain, often resulting in a hol and 50 percent laundry bleach. Wound helical-shaped canker (fig. 28b). Phloem, dressings are of little value. Early detec- cambium, and sapwood mortality cause tion and removal of diseased trees in plan- parts of the crown to wilt suddenly and tations can reduce losses. “Sanitation then die (fig. 28e). In the South, older cuts” of diseased stands should precede cankers are often colonized by L. planting sycamore trees in adjacent areas. theobromae (p. 30).

Figure 28-(a) Diagonal line from top center to lower right of bole defines right margin of a canker stain canker; (b) the same canker shown in (a) after removing the bark

28 Figure 28 (continued)-(c) Canker stain canker several years old with decay and woodpecker holes; (d) wedge-shaped, dark staining extends from the dead cambium into the sapwood; (e) mature sycamore with crown dieback resulting from canker stain disease.

29 Botryosphaeria Canker, Botryosphaeria rhodina (Cooke) Arx

Importance.-This fungus attacks with the wood grain. As the fungus ad- many species of woody and herbaceous vances in the sapwood, it causes a dark plants worldwide. In the South, B. rhodina stain that can be seen beneath the bark causes cankers, dieback, and mortality in and in cross sections of the stem. natural stands and plantations. Biology.-Conidia typically enter Identifying the Disease.-Cankers, wounds made by cultivating, harvesting, ranging in length from a few centimeters or insects. Canker formation and disease to several meters, form on twigs, development are enhanced by stress from branches, and main stems. Young and drought, poor site conditions, or other active cankers may be hard to see until diseases such as a wilt or canker stain (p. sections of bark die revealing canker mar- 28). Cankers grow faster, and seedlings gins and fruiting bodies breaking through are killed more quickly at warmer tem- the bark (fig. 29a). Old, inactive cankers peratures (30-35 “C). appear sunken and are typically sur- Control.-Promoting tree vigor by rounded by a callus ridge (fig. 29b). Die- planting sycamores on good sites and back occurs above plant parts girdled by avoiding dry, sandy sites should reduce a canker. the incidence of Botryosphaeria cankers. Identifying the Fungus.-The Pruning ornamental sycamores and asexual form of the fungus, Lasiodiplodia thinning or harvesting plantations (where (=Botryodiplodia) theobromae (Pat.) regeneration is by coppice growth) should Griffon & Maubl.) occurs more com- be done in the fall and winter monly than Botryosphaeria rhodina. (temperatures I 20 “C) when the fungus Many black, pinpoint-sized pycnidia oc- is less active. cur in groups, sometimes in rows, aligned

Figure 29-(a) Active Botryosphaeria canker on a sycamore stem; (b) inactive Botryosphaeria canker surrounded by callus on a sycamore stem. Anthracnose-Twig Canker and Shoot Blight, Apiognomonia (=Gnomonia) veneta (Sacc. & Speg.) Hahn. Importance.-Anthracnose is one of do not girdle a branch in a year have cal- the most important diseases of sycamores lous ridges at the margins. and Platanus species worldwide. It oc- Identifying the Fungus.-Colorless, curs in sycamore trees throughout North ascospores, which have two unequal cells, America. Severe defoliation in consecu- are released in spring from black perith- tive years can weaken trees, making them ecia on fallen leaves. Conidia are pro- susceptible to attacks from other agents duced in small cups on dead leaves in and even causing death. spring and in small (0.5 to 0.9 mm) black Identifying the Disease.-This fun- pycnidia in the bark of twigs. gus causes cankers on branches, blight- Biology.-Cankers form in the dor- ing of twigs and shoots, and blighting of mant season when temperatures are warm leaves (p. 22), which can, in some years, enough for fungal growth. Within 2 weeks cause near total defoliation. Newly after bud break, temperatures above 15 emerged leaves and young shoots are “C favor healthy shoot development, killed in early spring, often following cold whereas temperatures below 12 “C slow weather, which causes the symptoms to shoot growth and favor the killing of be mistaken for frost damage (fig. 30a). shoots and twigs. The antbracnose fun- Repeated shoot dieback can cause an an- gus probably enters sycamore trees gular branch pattern in older trees as through their leaves; canker formation and shoots from lateral buds replace dead ter- shoot blight occur in subsequent years. minals. Cankers (3 to 8 cm long) form on Control.-(See p. 22). small branches (fig. 30b), and those that

Figure 3&(a) Shoot blight, caused by sycamore anthracnose, can be mistaken for frost damage; (b) branch canker, with a callus ridge, from a sycamore anthracnose infection. Hypoxylon Canker, Hypoxylon tinctor (Berk.) Cooke

Importance.-Hypoxylon tinctor is a cm x 2 to 30 cm) may be evident through fairly common saprophyte of dead sy- sloughing bark or may be partially con- camores and other hardwood species. The cealed by bark (fig. 31~). Ascospores are fungus occasionally produces cankers on produced in tiny cavities embedded in the live sycamores, taking advantage of trees hard surface of the stromata. in “decline” or under stress. In Georgia, Biology.-The occurrence of H. it has been associated with cankers caused tinctor seems to be associated with ex- by the canker stain fungus Ceratocystis tensive thinning in natural stands, where fimbriata $ platani (p. 28). other fungal pathogens and sun scald may Identifying the Disease.-Irregularly be weakening trees. Infection by wind- defined, somewhat inconspicuous cankers blown or rain-splashed ascospores prob- tend to follow the wood grain, occurring ably occurs through wounds in the bark. mostly on the main stem and larger Control.-H. tinctor apparently is branches (fig. 31a). Older, decayed can- less able to infect healthy, vigorously kers nq have holes from insect borers growing trees. Therefore, maintaining or woodpeckers (fig. 31b). good tree vigor and minimizing bark Identifying the Fungus.-The dark- wounds should prevent cankers caused by brown to black fungal stromata (1 to 5 this fungus.

Figure 3 l-(a) Hypoxylon canker with bark removed to reveal fungal stromata; (b) dead, decaying limb showing dark fungal stromata and a woodpecker using the limb as a nesting site; (c) closeup of H. tincfor fungal stromata.

32 Miscellaneous Cankers, Phomopsis scubru, (Sacc.) Traverso; Dothiorellu sp.

Importance.-These fungi cause can- Identifying the Fungi.-Both fungi kers that are generally less of a problem form spores in small, light-colored, flask- than the canker fungi mentioned earlier shaped fruiting bodies (usually pycnidia) in this guide. Phomopsis scabra and formed on host tissue. Phomopsis scabra Dothiorella sp. can cause serious dieback conidia are colorless, spindle-shaped, or and mortality when environmental con- slightly curved single cells. Dothiorellu ditions weaken the host. spores are colorless, one-celled, and oval. Identifying the Disease.-Phomop- Biology.-Phomopsis scabra cankers sis scabru can cause cankers ranging from seem to develop readily at temperatures 10 cm to 1 m in length and may be mis- below 24 “C. Growth of Dothiorella can- taken for cankers caused by kers slows during the growing season al- Botryosphaeriu rho&a (p. 30). Cankers lowing callus tissue to form. Spores of of both fungi are usually associated with both fungi are spread by wind, rain, in- dead buds, terminals, or lateral branches sects, and mechanical means. They enter (fig. 32). At first, cankers may go unde- through wounds. tected until the disease has progressed Control.-Damage from these fungi enough to cause small, off-color leaves, can be reduced by preventing wounds and branch dieback, or tree death. Cankers promoting tree vigor by planting on good will become dark and sunken after 1 to 2 sites. growing seasons.

Figure 32-Phomopsis cankers on branches of a site-stressed sycamore. ROOT AND BUTT ROTS

Armillaria Root Rot, Armilluria tabescens (Stop.) Dennis, Orton & Hora

Importance.-Armillaria root rot is Biology.-The fungus survives as one of the most common and damaging mycelium in the roots and stumps of dead diseases of many hardwood forest and trees from which it spreads to adjacent shade trees in North America. However, trees. Trees weakened by mechanical it occurs less often on sycamores than on wounding or stressed by other pests are other hardwood species. more susceptible to attack. Identifying the Disease.-Trees ex- Control.-Prevention is difficult be- hibit a loss of vigor and gradual decline, cause the fungus is prevalent in woody yellowing of foliage, growth reductions, debris in the soil and has a wide host premature leaf drop, and branch dieback. range. Wounding of tree trunks or sever- In severe cases, and, given enough time, ing roots with cutting tools or heavy A. tubescens can kill a tree. equipment should be avoided. Minimize Identifying the Fungus.-Following stress to landscape and shade trees by pro- rains, clusters of A. tabescens may form moting tree vigor through watering dur- at the base of diseased trees or from their ing periods of drought and fertilizing dur- roots. The mushroom is honey colored to ing the growing season. Roots and stumps brown, with white gills and a round cap of trees killed by A. tabescens should be that is 4 to 15 cm in diameter (fig. 33a). removed to reduce sources of inoculum White, perforated fungal mats that form that could infect surrounding trees. Con- beneath the bark at the root collar, or on trol other insect and disease pests that can roots, are diagnostic (fig. 33b). reduce vigor and weaken resistance to infections.

-___. -. .-.

Figure 33-(a) Mushrooms and (b) mycelial mats (of Armillaria tabescens. Hericium Butt Rot, Hericium erinaceus (Pers.:Fr.) Murr.

Importance.-Hericium butt rot most rainy autumn and winter months. They are commonly occurs in oaks, but it is also initially round and smooth on all surfaces, found in many other hardwoods through- but develop long, pendant “teeth” on the out the Eastern United States, including lower surface and gradually turn yellow- sycamore, beech, birch, hickories, maples, ish with age (fig. 34). and persimmon trees. Biology-Spores of the fungus, re- Identifying the Disease.-The fun- leased from fruiting bodies on infected gus causes a white, soft, and spongy rot trees, germinate and infect trees through of heartwood in the butt and lower bole fire or logging scars, stem cracks, and of the tree. Decayed wood eventually dis- branch stubs near tree bases. Fruiting bod- integrates leaving a cavity in the center ies form after extensive decay of the heart- of the tree. Because external cankers are wood has occurred. not formed in the outer bark, no evidence Control.-Hericium butt rot is best of the disease is visible except for sea- controlled when thinning stands by pre- sonal fruiting bodies. venting wounds and broken branches on Identifying the Fungus.-Large (up residual trees caused by logging equip- to 30 cm wide), soft, white, and fleshy ment, skidding logs, and falling trees. Pre- fruiting bodies form on the boles of liv- venting fire scars is also suggested. ing trees, singly or in clusters, during the

Figure 3iCFruiting bodies of Hericium ehaceus on a fire-scarred sycamore. Oxyporus Root Rot, Oxyporus latemarginatus (Durieu & Mont.) Donk

Importance.-Oxyporus root rot fested, forming a white crust of mycelial causes decay of roots and root collars in strands on the soil surface at the stem base. sycamore, cottonwood, and many other Biology.-Oxyporus latemarginatus hardwoods in the South. colonizes and survives on dead wood or Identifying the Disease.-Few diag- roots in the soil from which it invades nostic symptoms are known for this dis- small feeder roots of healthy trees. It then ease. Young trees exhibit reduced annual spreads to the root collar, colonizing the growth, stunting, and high mortality, outer and inner bark, cambium, and sap- whereas older trees often survive several wood. years. The fungus causes a spongy white Control.-Trees are predisposed to rot of the sapwood and enlarged cankers attack during warm weather, especially on the outer bark. when the soil is waterlogged, or when Identifying the Fungus.-The fun- feeder roots are wounded mechanically gus invades the sapwood of roots as well or by fire. The disease can be managed as the wood behind fire scars in the lower by preventing fiie and mechanical wound- bole, forming white mycelial mats and ing to roots and the lower trunk and by dirty white to pale yellow fruiting bodies maintaining adequate soil drainage. Tree at the soil line of dying or recently killed vigor should be maintained by watering, trees. The fruiting bodies are active for fertilizing, and controlling weeds. If pos- one season (fig. 35). Soil around diseased sible, soil with infested dead wood should roots and the root collar may become in- be removed.

Figure 35-Fruiting body of Oxyporus latemarginatus on a young sycamore stem.

36 Ganoderma Butt Rot, Gunoderma Zucidum (Curtis:Fr.) P. Karst.

Importance.-This fungus is one of fruiting body has pores. Brown spores the most commonly observed causes of released from fruiting bodies often form butt rot in southern hardwoods. A true a dustlike coating on grass, bark, or the pathogen, it is often responsible for pre- fruiting bodies themselves. mature death of residential and landscape Biology.-Ganoderma lucidum in- trees. It can kill large trees and frequently fects trees through wounds on roots or the causes decay in declining trees. lower bole caused by tools, lawn mow- Identifying the Disease.-Gano- ers, and falling trees or limbs. The decay’s derma lucidum causes a white, spongy lethal effects occur when living cells in soft rot of sapwood and heartwood in the the sapwood are killed. A decay column roots and lower bole. Diseased trees even- may form for many years before sufficient tually lose vigor, bear undersized leaves damage causes visible symptoms in the and dead branches, and sometimes have crown. Fruiting bodies eventually form wilted or yellow leaves. However, fmit- and may occur repeatedly during the sum- ing bodies may form at or near the ground mer months. Living trees with decay in on apparently healthy trees. the roots or lower bole are subject to Identifying the Fungus.-The upper windthrow (fig. 36b). surface of G. lucidurn’s large, reddish- Control.-This disease is best con- brown fruiting bodies usually has a shiny, trolled by preventing mechanical wounds varnished look and a leathery texture (fig. to the lower bole and roots. Care should 36a). The fruiting bodies may form sin- be taken not to injure landscape trees, gly or in overlapping clusters at ground especially when using heavy equipment level or on the lower bole of sycamores. to clear land when preparing sites for The margins are white, becoming a tawny home building. yellow with age. The lower surface of a

Figure 3&(a) Note the glossy, red-brown top and stalk of this G. lucidum fruiting body; (b) advanced decay in this canker, along with insect and bird damage, poses a hazard.

37 Scytinostroma Root Rot, Scytinostroma (=Corticium) galactinum (Fr.) Donk Importance.-Seedlings of sycamore when soil is removed from the base of a and other southern hardwoods such as tree. Fruiting bodies of this fungus are I sweetgum, white oak, and nuttall oak are very small and inconspicuous, forming very susceptible to Scytinostroma root rot. from fungal mats on the roots and root The pathogen may kill young seedlings collar. within a month to a year after infection. Biology.-Scytinostroma galactinum Fortunately, the disease is not common in infects trees through wounds at the root southern sycamores. collars of seedlings. Lateral and feeder Identifying the Disease.-The fun- roots often are killed. The fungus can then gus causes a white rot of roots in the col- survive on dead roots and stumps and lar and lateral roots of the taproot. Lat- spread to living roots. Spores from fruit- eral roots may decay and, in severe cases, ing bodies also may produce hyphae that separate from the taproot. Infected seed- infect seedlings. lings may be dwarfed, have thin crowns, Control.-Sycamore seedlings and yellowing or dead leaves, and exhibit re- saplings are most susceptible to this dis- duced vigor or decline prior to death. ease. Care should be taken to prevent the Dead leaves usually remain on the plant mechanical wounding of the root collar after death. and lateral roots of seedlings. Removal Identifying the Fungus.--Scytino- of diseased seedlings will help minimize stroma galactinum produces thick, white the fungus’ spread to healthy seedlings, fungal mats on the surfaces of the root but no controls are feasible in natural collar and roots below the collar (fig. 37). stands. Fungal mats are visible below the soil line

Figure 37White mycelial mats on roots and root collars of young sycamore (top) and cottonwood (bottom) trees.

38 PARASITIC PLANTS

Mistletoe, spp. Importance.-Extensive infections Biology.-Mistletoe is a perennial and mortality are not common in sy- evergreen plant that grows on tree camore trees. Infections usually occur in branches from which it draws water and openly grown trees. Phoradendron plants nutrients. Its seeds are covered with a are commonly used as greenery in Christ- sticky, gelatinous coating and are spread mas decorations. by birds and animals. Seeds germinate Identifying the Injury.-An affected where they lodge on young branches, and branch may have a gall or swelling at the a rootlike structure penetrates the branch site of infection, and multiple infections and produces a mistletoe plant. One spe- may retard growth. Stunting and dieback cies, l? serotinum, affects many broadleaf may occur beyond where the mistletoe tree species in the South and East but is plant is attached to its host. limited by temperature in its northern Identifying the Parasite.-Mistletoe range (Kansas to New Jersey). Several has stout, woody, green stems and dark- other species of Phoradendron occur in green, leathery leaves (fig. 38a). It is seen the West. most easily in winter growing on scaffold Control.-Control of mistletoe in sy- and minor branches and twigs of the host camores is normally not needed but can (fig. 38b). The plant has opposite branch- be done by cutting the host branch at least ing, inconspicuous flowers, and produces 30 cm below the point of infection. white berries in the fall and winter.

Figure 38-(a) Closeup of a mistletoe plant; (b) mistletoe infections in a mature sycamore. AIR POLLUTION AND CHEMICAL INJURIES Air-Pollution Injury Chemical Injury Sycamore trees are sensitive to ozone, Sycamore trees are sensitive to several sulfur dioxide, and fluorides, which are agricultural pesticides, including herbi- released from point-source industrial cides and fungicides that are commonly plants. Consequently, injuries from air- used to control pests in field crops. borne pollutants often occur near these Clomazone and phenoxy compounds like plants. Airborne pollutants may also cause 2,4-D, are examples of herbicides that can damage to trees for some distance down- cause chemical injuries when they drift wind of the source. Pollutants damage during aerial applications. At higher con- plant foliage by oxidative processes that centrations, these materials produce interrupt normal physiology. Symptoms symptoms of leaf distortion, curling, and include stippling, interveinal and marginal chlorosis (fig. 39c, d). Solvent carriers in chlorosis, and general bleaching of leaves fungicide sprays can damage sycamores. (fig. 39a). Reducing point-source emis- Damage from pesticide spray drift can be sions is the only known control. Drought avoided by carefully planning applica- stress (fig. 39b) and some pathogens (e.g., tions and spraying during periods of low p. 24), can cause leaf symptoms that may wind. be mistaken for air-pollution injury.

Figure 39-(a) Tan flecking caused by ozone injury; (b) interveinal necrosis from drought stress; (c) bleaching of leaves caused by the herbicide clomazone; (d) cupping, curling, and necrosis of leaves caused by the herbicide 2,4-D.

40 MAINTAINING TREE HEALTH

Because healthy trees are less susceptible 5. Ensure that trees receive sufficient to attack and injury by insects and dis- water, nutrients, and sunlight through ir- eases, sycamore plantings should be rigation, fertilization, proper spacing, and managed to optimize vigor. Seedlings other intermediate stand-management and saplings that become stressed when practices, such as timely thinning and planted “off site” or on marginal sites, crop-tree release cutting. and become further weakened by drought 6. Use sanitation practices such as prun- or other factors, are sometimes devas- ing, removing dead and symptomatic tated by disease. The following cultural branches, and raking, discing under, or practices, singly or in combination, are removing diseased and insect-infested suggested to promote and maintain good leaves. Such practices reduce buildup of tree health in forest stands, plantations, overwintering fungal inoculum and hiber- nurseries, shelterbelts, and ornamental nating insects in plant debris that can plantings: cause new pest problems the following year. 1. Plant sycamore in deep, well-drained, loamy soils with a good supply of ground 7. Prevent or minimize injuries by har- water such as alluvial soils, terrace soils, vesting and cultivation equipment, fire, or and fertile sites in coves and lower slopes. other sources that can create entry points Site selection is the single most impor- for canker fungi, wood-decay fungi, and tant factor in maintaining tree health and insect borers. minimizing losses from diseases and in- 8. If pruning must be done, schedule it sects. for the dormant season when fungi are in- 2. Where possible, avoid planting sy- active and less likely to colonize fresh camores on abandoned old-field sites wound sites. Always sterilize pruning with well-developed, impermeable hard- tools with a solution of 50 percent laun- pans, especially those that have been dry bleach and water before moving to badly eroded and leached. the next tree. 3. Use only vigorous planting stock (of 9. Losses from canker diseases may be adequate size and free of root and stem reduced substantially by early detection diseases) produced in nurseries that and shortened cutting cycles. However, strictly follow recommended practices when a shorter cutting cycle is not pos- for growing, lifting, storing, and handling sible, cankered trees should be felled and seedlings and cuttings. destroyed or removed to minimize disease spread. Sanitation cuts of unmerchantable 4. When it is available, use planting stands containing canker diseases are rec- stock from improved selections grown in ommended when adjacent sites are to be sycamore seed orchards or from a locally planted in sycamore. adapted seed source. (Some research has shown that plants from seed sources north 10. Managers should learn to identify of a planting site are more severely dam- serious diseases such as canker stain. , aged by certain canker diseases than Identification errors can result in prema- those from seed sources south of the ture and unneeded salvage harvest or fail- planting site.) ure to harvest trees that will die or be- come unmerchantable before the next for the greatest number of pest-manage- cutting cycle. ment options. 11. Strictly follow label guidelines when 13. Insect pheromones and traps are using herbicides around ornamental available commercially for monitoring a plantings and shade trees as well as in number of species. Determining local, nurseries and young plantations. Ad- seasonal abundance can help establish the equately shield young trees from direct need for control and proper timing of in- contact or spray drift. When used improp- secticide application. erly, herbicides can injure young sy- 14. For information on pesticides or ad- camore trees. ditional assistance with sycamore pests, 12. Examine plantings regularly for dis- contact your State Forester, county exten- ease symptoms and the first signs of in- sion agent, or the nearest office of the sect feeding. Early detection will allow USDA Forest Service, State and Private Forestry, Forest Health Protection.

42 We appreciate the constructive re- (Colombian timber beetle); G.J. Lenhard, views of this manuscript for scientific Louisiana State University, Baton Rouge, content from: Edward Barnard, Division LA (whitefringed beetle adult); G.W. of Forestry, Forest Health Section, Zehnder, Auburn University, Auburn, AL Gainesville, FL; Richard Goyer, Louisi- (whitefringed beetle larvae); R. J. Stipes, ana State University, Baton Rouge, LA; Virginia Polytechnic Institute and State Lynne Thompson, University of Arkan- University, Blacksburg, VA (untreated sas at Monticello, AR; and R. Jay Stipes, sycamores with anthracnose vs. fungicide- Virginia Polytechnic Institute and State treated sycamore); J.L. Sherald, Center University, Blacksburg, VA. for Urban Ecology, National Park Service, We gratefully acknowledge the fol- Washington, D.C. (branch symptoms lowing individuals or agencies for photo- caused by Xylellufustidiosa); J.N. Bruhn, graphs or specimens for making photo- University of Missouri, Columbia, MO graphs of some pests: J.F. Butler, Univer- (fruiting bodies and mycelial fan of sity of Florida, Gainesville, FL (white Armillaria tabescens); L.W. Kress, marked tussock female moth); L.C. Th- USDA Forest Service, Research Triangle ompson, University of Arkansas at Park, NC (ozone injury). Monticello, Monticello, AR (fall web- We also wish to thank the current and worm egg mass, drab prominent larva, former staff at the Southern Hardwoods case-bearing leaf beetle larva); W.T. Laboratory, Stoneville, MS, and the Johnson, Cornell University, Ithaca, NY Southern Hardwood Forestry Research (sycamore plant bug and leaf injury, Group, Stoneville, MS, for help in locat- American plum borer injury); R.J. Gill, ing insect infestations and disease prob- California Department of Food and Ag- lems in the field to study and photograph riculture, Sacramento, CA (European fruit and for technical advice during this lecanium); EM. Davis, USDA ARS, Mis- project. Former staff of the Southern sissippi State University, MS (European Hardwoods Laboratory also provided corn borer larva); J.C. Nord (retired), photographs that were used in this project. USDA Forest Service, Athens, GA GLOSSARY acervulus(-i): a saucer-shaped fungal ELISA test: enzyme-linked immune- structure embedded in host tissue in which sorbent assay; a test that detects a spe- conidia form. cific molecule, usually a protein, consis- ascocarps: the sexual fruiting bodies of tently associated with a certain organism. Ascomycetes. elytron (a): hard leathery forewing of Ascomycetes: a large group of fungi char- beetles. acterized by producing spores in a sac- frass: wood fragments mixed with excre- like structure (ascus). ment produced by insect larvae. ascospores: sexual spores of Asco- hair pencil: tuft of long upright parallel mycetes. setae (hairs). basidiocarps: the sexual fruiting bodies hypha(-e): a fungal filament. of Basidiomycetes. inoculum(-a): the spores, mycelium, or Basidiomycetes: a large group of fungi other propagules of a pathogen that ini- characterized by producing spores on a tially infect a host. club-like structure (basidium). microsclerotium(-ia): a firm, often basidiospores: sexual spores of Basidi- rounded, compact mass of fungal hyphae omycetes. that are packed together to form a resis- bole: the main trunk of a tree. tant structure. butt: the lower bole of the main stem. mycelium(-ia): a collection of hyphae that make up a fungus body. callus: a protective tissue that forms to cover wounds on stems and branches. necrotic: composed of dead cells. cambium: a thin layer of meristematic perithecium(-ia): flask-shaped ascocarps cells between the bark and wood. in which ascospores are formed. cankers: a definite localized necrotic le- saprophytic: the ability to grow on dead sion of the bark and cambium. plant tissue. cleistothecimu(-ia): roundish ascocarps sapwood: the outer, water-conducting of powdery mildews, typically with ap- wood of the tree stem. pendages, in which ascospores form. sporodochium(-ia): a cushion-shaped conidium(-ia): an asexual fungal spore. stroma covered with conidiophores. damping-off: a disease of seedlings that stroma(-mata): a mass or mat of hyphae causes rotting of the hypocotyl and pre- in or on which fruiting bodies form. vents shoot emergence, or causes a new shoot to fall over. dieback: the gradual dying of a tree crown usually from the top down and from the outside in.

44

Leininger, T.D.; Solomon, J.D.; Wilson, A.D.; S&if& N.M. 1999. A Guide to major insects, diseases, air pollution injury, and chemical it-jury of sycamore. Gen. Tech. Rep. SRS 28. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 44 p.

This booklet will help nurserymen, forest woodland managers, pest control operators, and homeowners to identify and control pest problems on sycamore trees. The major insect and disease pests of sycamores in the Eastern United States are emphasized. Descriptions and illustrations of the pests and the damage they cause are provided to aid in identification. Brief notes are given on biology and control to aid in predicting damage and making control decisions.

Keywords: Bacteria, biology, borers, control, defoliators, fungi, identification,