While on a walkabout in Winton Woods (Great Parks, Hamilton County) earlier this week, I came across a Black Maple (Acer nigrum) with new shoots and leaves that were wilted and blackened. The black maple was at the edge of a forest and had not been planted.
The symptoms resembled frost/freeze damage, which has appeared on many deciduous trees this spring in Ohio. Jim Downs (OSU Extension, Field Specialist, Forestry) covered the damage in his BYGL Alert posted on May 6 titled, "Why Are My Trees Wilting?" [ https://bygl.osu.edu/node/2632 ].
However, a close examination of the affected terminal shoots revealed stem tunneling and a moth caterpillar. The culprit was most likely the Maple Shoot Borer, Proteoteras aesculana (Lepidoptera, family Tortricidae). The moth may also be called the “maple tip moth” and “maple twig borer.”
The literature notes that most North American maples may serve as a host for the caterpillars. The moth has long been a significant pest of maples in nurseries from the East Coast to the Pacific Northwest.
The moth focuses its stem-boring activity on maples in the spring. As the caterpillars tunnel the stem, they consume the vascular and structural tissue, causing the new terminal shoots to develop symptoms that mimic frost/freeze damage.
This is the first time that I’ve observed damage by the maple shoot borer on its namesake host growing in forests or landscapes in southwest Ohio. The symptoms look nothing like the annual leaf-shedding damage commonly produced in my part of the state by the sawfly called the Maple Petiole Borer (Caulocampus acericaulis, family Tenthredinidae).
This non-native sawfly was introduced into the United States from Europe. Although the sawfly prefers sugar maples (A. saccharum), other maples may occasionally be infested.
The petiole borer does not cause shot damage. The grub-like sawfly larvae feed by boring down the center of the petiole. It causes premature leaf drop, with affected leaves appearing perfectly healthy, or they may wilt and turn brown while still attached to the tree. However, all of the fallen leaves will retain only a very small portion of a hollowed-out petiole.
Selected References
Hale, F. A., & Halcomb, M. (1995). Timing and control of Proteoteras aesculana (Lepidoptera: Tortricidae) in red maple. In Proc S Nurs Assoc Res Conf (Vol. 40, pp. 198-200).
Hale, F. A., & Halcomb, M. (1994). Shoot boring caterpillars, Proteoteras spp.(Lepidoptera: Tortricidae): major pests of red maple in Tennessee nurseries. S. In Nurs. Assoc. Res. Conf (Vol. 39, pp. 178-179).
Potter, D. A., Seagraves, B., Tittle, S., Redmond, C., & Haynes, K. F. (2007). Managing Maple Shoot Borer: Implementation in Kentucky Production Nurseries. UK Nursery and Landscape Program, 19.
Schuh, J., & Mote, D. C. (1948). Insect pests of nursery and ornamental trees and shrubs in Oregon. Agricultural Experiment Station, Oregon State University (College), Corvallis. Station bulletin 449. 164 pp.
Seagraves, B. L., Haynes, K. F., Redmond, C. T., Tittle, S., & Potter, D. A. (2008). Seasonal biology and management of the maple shoot borer, Proteoteras aesculana (Lepidoptera: Tortricidae), in production nurseries. Pest Management Science: formerly Pesticide Science, 64(10), 1040-1049.
Vanek, S.J., (2011). Maple Shoot Borer [Fact Sheet]. University of Kentucky, Dept. of Entomology, ENTFACT-455.
https://entomology.mgcafe.uky.edu/ef455
