Trap response and fruit damage by obliquebanded leafroller (Lepidoptera: Tortricidae) in pheromone-treated apple orchards in New York

Pheromone disruptants were tested from 1989 to 1992 in western New York to determine effect on trap catch and potential use in the control of obliquebanded leafroller, Choristoneura rosaceana (Harris), using polyethylene tube tie and controlled-release membrane dispensers in plots of 0.2-2.4 ha. Effectiveness of pheromone at different application rates and canopy locations was evaluated using synthetic pheromone-baited traps, molasses-baited traps, and by inspecting foliar terminals and fruit for leafroller damage. All pheromone treatments significantly reduced (by 56-97%) pheromone trap catches of male moths compared with catches in nontreated blocks. One application of a natural-blend formulation at 988 dispensers per hectare was better than 494/ha at disrupting trap catch of both flights that occur during the year. However, mated female moths were present in the orchard center as frequently as anywhere else in a pheromone-treated block, indicating either immigration from outside sources or resident females that were not prevented from mating by the pheromone. The membrane dispenser emitted the S-component natural blend at proportions similar to those in wild female moths. Pheromone traps placed in the tops of trees in a pheromone-treated orchard always caught higher numbers of male moths than those in lower- or middle-canopy positions. Pheromone treatment resulted in fruit damage similar to that of a pheromone + insecticide treatment under low to moderate leafroller population pressure (i.e., 3-5% fruit damage in untreated orchards); however, no control method was able to reduce damage to acceptable levels in all cases.