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 L.) is a common tree and one of the largest in eastern deciduous forests. Other names are American sycamore, American planetree, buttonwood, and buttonball-tree. Its native range includes the area east of the Great Plains from south-central Texas and eastern Nebraska eastward to Maine and Flordia. However, sycamore is planted as an ornamental in many Western States, especially California. It is also found in northeastern Mexico and southern Ontario. Sycamore is often a pioneer species on river fronts, upland old-field sites, and on strip-mined coal lands. However, it grows best and biggest on sandy loam soils with a good ground water supply, typically on alluvial sites along rivers and in bottomlands. Sycamore timber is valued for both lumber and pulp and is also planted widely as a shade tree because of its broad, dense crown, exfoliating bark on mature stems, and distinctive thin, green to greenish-white bark on scaffold branches and young stems. Easily propagated from seeds or cuttings, and second only to cottonwood in growth rate, sycamore lends itself well to artificial regeneration and intensive culture. It is among only a few hardwood species used to establish commercial plantations, an effort that typically requires intensive site preparation, early weed control (cultivation or herbicides or both), fertilization, and, in some cases, irrigation. Some plantations have been established at very close spacing and are being regenerated from coppice on short rotations to maximize fiber production. This kind of culture has been termed “short-rotation forestry,” “silvicultural biomass farming,” or “fiber farming.”

Insects, diseases, pollutants, and chemicals present continuous threats to sycamore growth and production. Many insects feed on sycamore, but few actually cause serious injury. Terminal-feeding insects can sometimes cause serious seedling mortality and misshaped stem form. Insect defoliators, perhaps the most common pests, may strip entire trees or stands in localized areas, weakening trees and causing growth loss. However, those pests seldom cause significant mortality. Insect borers rarely occur in large populations except in stressed or weakened trees and in transplanted ornamentals. Timber beetles sometimes seriously degrade sawtimber and sawlogs.

Sycamore production usually suffers more from diseases than from insects. In some years, leaf diseases can defoliate trees or entire stands, reducing radial and terminal growth and weakening trees, making them susceptible to other pathogens and insect pests. Canker diseases, the most damaging type of sycamore diseases, can cause branch dieback, top dieback, and bole cankers. Dieback and mortality caused by canker diseases, along with other factors, have been so serious in some plantations that a few timber companies in parts of the South have sycamore planting “on hold” until disease-control methods can be developed.

Cultural practices that maintain and promote tree health help minimize losses caused by pathogens and insects. It is better to prevent attack by pathogens and insects than to remedy the aftermath of an attack. Some recommendations are provided in the back of this guide under “Maintaining Tree Health.” Chemical or other direct controls may be needed as a last resort.

This guide will help nursery workers, forest managers, insect-pest and disease-control specialists, and homeowners to identify and control insect pests and diseases of sycamore trees. It emphasizes major diseases and insect pests in the Eastern United States and includes descriptions and illustrations of pathogens and insects, as well as the damage they cause. To aid in assessing the risk of further damage and making control decisions, brief notes describe the biology and control of pathogens and insects.

We have described pathogens and insects both with common names and Latin binomials, including taxonomic authorities. However, a distinction must be made between the treatment of disease and pathogen nomenclature and that of insects. The common name of an insect refers to the insect itself. The common name of a disease typically includes the latin name for the genus of the pathogen causing the disease. For example, the fungal pathogen Cylindrocladium scoparium causes the disease Cylindrocladium root rot. For simplicity, we have omitted the words “caused by” between each disease name and its respective pathogen name.

Specific chemical controls are not listed because recommendations change whenever compounds are discontinued or new materials are approved. For information on pesticides or additional assistance with managing sycamore pests, the landowner should contact his or her county extension agent, State Forester, or the nearest office of the U.S. Department of Agriculture, Forest Service, State and Private Forestry, Forest Health Protection.

T.D. Leininger and A.D. Wilson are the Principal Research Plant Pathologists, J.D. Solomon is the Principal 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.