EFFECTS OF SUMMER PRUNING AND HAND FRUIT THINNING ON OBLIQUEBANDED LEAFROLLER (LEPIDOPTERA, TORTRICIDAE) FRUIT DAMAGE IN NEW-YORK-STATE APPLE ORCHARDS

Two commercially used horticultural practices, summer pruning and frui t thinning by hand, reduced fruit damage caused by the obliquebanded l eafroller, Choristoneura rosaceana (Harris), in apple orchards in New York. Results of a 2-yr study indicate that fruit thinning by hand red uced fruit damage by 2-3% in large and small trees, whereas the use of summer prunning reduced fruit damage by 4-6% in large, vegetative tre es. Summer pruning had no effect on fruit damage in small trees. Pruni ng early in the growing season can increase fruit damage and decrease flower production the following year. Hand fruit thinning increased fr uit size, and summer pruning increased fruit color. These findings ind icate that horticultural techniques commonly used in commercial apple production can be slightly modified to aid in the control of obliqueba nded leafrollers.