Solomon, J. D.; Payne, J. A. A guide to the insect borers, pruners, and girdlers of pecan and hickory. Gen. Tech. Rep. SO-64. New Orleans, LA: USDA Forest Service. Southern Forest Experiment Station; 1986. 31 p.
Pecan, Carya illinoensis (Wangenh.) K. Koch, and at least 10 species of hickory, Carya spp., are native to the Eastern United States. Eight of these are economically important when grown for timber production, commercial nut production, ornamental purposes, and wildlife food. Pecan is best known for its nutritious nuts, which are produced in quantities that make them a major economic commodity, but is also a prized species for use in fine furniture and paneling (Kennedy and others 1981). During recent years, it has been commonly called the "black walnut of the South," and interest in commercial plantings is growing because of its high stumpage value (Adams and Thielges 1976-77). The hickories have long been known for their use in the manufacture of handle stock, sporting goods, and some furniture.
Insect borers, pruners, and girdlers are injurious pests of pecan and hickory. Although most of these pests have a wide distribution, they seldom threaten trees over large areas. Damaging populations typically occur on a local basis, such as a nursery, individual nut-producing grove, forest stand, young timber plantation, or ornamental trees in a neighborhood or small geographic locality. Much has been written on the insect pests affecting the nuts and foliage of pecan, but little has been published on the insect borers affecting the tree itself. The cryptic habits of the insect borers have hampered efforts to document this group of pests. Known information is widely scattered and found in older literature, much of which is not generally available to those who need to use it.
The terminals, branches, trunks, and roots of trees of all sizes are vulnerable to borers. Natural regeneration is sometimes heavily infested by girdlers and pruners. Nurseries and young plantings located close to heavily infested stands or woodlots are most likely to be damaged. Loss of terminals and main stems in young timber plantations adversely affects tree form. Pruners and girdlers can drastically reduce the number of nut-bearing branhes and subsequent nut crop of nut-producing trees. Girdled branches can create cleanup problems on residential properties. Young transplanted trees are particularly susceptible to borers and often need protection. Borer holes and associated stain and decay cause defects in the wood that reduce its value for lumber, veneer, handle stock, and other products. Wormholes and bark scars also adversely affect the aesthetic beauty of shade and ornamental trees. Borers sometimes invade the cambium and callus around new grafts and prevent union of scion and stock; recently top-worked trees have suffered serious damage in the past. Stressed trees are particularly susceptible to bark beetles and pin-hole borers. Bark beetles have caused widespread mortality of hickory during extended periods of drought. Yellow-bellided sapsuckers are included in this guide because the holes they peck in the bark are often confused with those caused by insect borers.
Impact from pests can be minimized through good management. Cultural practices that maintain and promote tree vigor are of utmost importance. New plantings should be on good sites, preferably away from heavily infested stands, woodlots, or old, deteriorating orchards. Adequate space, water, and nutrients should be provided. Efforts should be made to keep injuries such as cuts, bruises, and broken limbs resulting from cultivation, mowing, thinning, and harvesting equipment to a minimum. Injuries that do occur should be promptly treated to speed the healing process. Practices such a "pick-up and destroy" and "prune-out and destroy" can help to reduce damage by girdlers and pruners, especially when practiced on an area or neighborhood basis. When possible, practices should be adapted that favor natural controls such as predators, parasities, and insect pathogens. Chemical control may occasionally be needed.
This publication should aid forest managers of timber resources, farm managers of nut producing groves, extension and pest control personnel, and homeowners to identify, manage, and control the major insect borer, pruner, and girdler pests of pecan and hickory. Descriptions and illustrations of the pests and their damage—including galleries, frass, size and portion of tree infested, and tree condition—are presented to aid in identification. Information on biology and control are given to help in predicting damage, managing populations, and making control decisions. Specific chemical controls are not given in this publication. For the latest information on pesticides contact your State Forester, Extension Agent, or the nearest office of State and Private Forestry, USDA Forest Service.
J.D. Solomon is research entomologist at the Southern Hardwoods Laboratory, maintained at Stoneville, MS, by the Southern Forest Experiment Station, Forest Service-USDA, in cooperation with Mississippi Agricultural and Forestry Experiment Station and the Southern Harwood Forest Research Group. J.A. Payne is research entomologist at the Southeastern Fruit and Nut Research Laboratory, Agricultural Research Service, USDA-Byron, GA.
