Mating disruption to control damage by leafrollers in Virginia apple orchards

Abstract

AbstractMating disruption for control of variegated leafroller (VLR), Platynota flavedana (Clemens), tufted apple bud moth (TBM), P. ideausalis Walker, and redbanded leafroller (RBL), Argyrotaenia velutinana (Walker), was studied in Virginia apple orchards in 1989 and 1990. In 1989, each dispenser (1000/ha) contained 190 mg of 67.2% E11–14:Ac, 28.8% Z11–14:Ac, 1.4% E11–14:OH, 0.6% Z11–14:OH, and 2% Z9–12:Ac (a putative generic leafroller disruption blend). Trap captures of VLR, TBM and RBL were reduced by 97%, 51% and 55%, respectively. Average leafroller injury in the interior and edge of the pheromone block was 3.8% and 2.7%, respectively. The conventional control and abandoned blocks had 0.05 and 27.5% injury, respectively. Dispensers containing E11–14:OH (70%) and Z11–14:OH (30%) (close to the natural blend of VLR), more effectively disrupted orientation to pheromone traps by both Platynota spp. than did the generic blend. In 1990, dispensers containing 150 mg of E11–14:OH (70%) and Z11–14:OH (1000/ha) were placed in two 2‐ha blocks and one 4‐ha block. One pheromone‐treated block was sprayed in August with phosmet for codling moth, not timed for leafrollers. Trap captures of VLR and TBM were reduced by almost 100% and 69%, respectively. RBL captures were not reduced by VLR pheromone permeation. Injury from Platynota spp. in pheromone block middles and edges ranged from 0.3–1.7% and 0.3–2.3%, respectively. Injury in conventional blocks ranged from 0–1.1%. RBL injury in pheromone block middles ranged from 0–6.1%, and in edges, 1.7–4.8%. Injury in control blocks ranged from 0–1.1%. Combined leafroller injury in an abandoned block was 18% (s.e. 0.3). Release rates averaged 30 and 32 mg/ha/h for the VLR and generic pheromone dispensers, respectively.