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Joseph F. Boggs, Ohio State University Extension, Hamilton County/Southwest District; Curtis E. Young, David J. Shetlar, James A. Chatfield, Erik A. Draper, Pamela J. Bennett, Gary Y. Gao, |
Borers
Infestations of several stress-related borers appeared to be common during the 2001 season. These included conifer bark beetles (family Scolytidae, genera Dendroctonus and Ips), which produce characteristic "shotholes" in the bark of infested trees, as well as the much larger metallic flatheaded beetles (family Buprestidae) that attack deciduous trees, such as bronze birch borer (Agrilus anxius), twolined chestnut borer (A. bilineatus), and flatheaded appletree borer (Chrysobothris femorata). These observations were virtually a repeat of previous seasons (5, 7, 8).
Damage caused by the buckeye/horsechestnut petiole borer (Proteoteras aesculana) has become common in southern and central Ohio (6, 7). During the 2000 season, significant damage was also observed on buckeyes in the northern part of the state (8). The trend continued this past season with damage being reported throughout the state. There are two generations per year, and symptoms produced by the first generation began appearing in late April. Larvae of the moth bore into leaf petioles causing the new leaves to turn black and droop. Leaves remain attached to the trees and symptoms in the spring superficially resemble freeze/frost injury.
The maple petiole borer (Caulocampus acericaulis), a sawfly that bores into the petioles of its namesake, was also active throughout much of the state. Unlike the buckeye petiole borer, feeding activity of the maple petiole borer causes affected leaves to fall from the tree. Heavy leaf drop in May often signals an infestation of this insect. The tiny sawfly tunnels out the inner tissues of the petiole causing the leaves to turn brown, droop, and the petioles to break a short distance from the leaf blade. Larvae remain inside the portion of the petiole attached to the twig, so raking and destroying fallen leaves will not reduce the population. There is only one generation per year and damage is seldom severe enough to cause serious harm to the tree.