MATING DISRUPTION FOR CONTROL OF DAMAGE BY CODLING MOTH IN VIRGINIA APPLE ORCHARDS

Polyethylene dispensers (Shin Etsu) containing 172 ml of the sex phero mone, (E,E)-8,10-dodecadien-I-ol (63%), dodecenol (31%) and tetradecen ol (6%), of codling moth (CM), Cydia pomonella (L.), were placed in ap ple orchards in Virginia. Two blocks of about 2 ha each were treated i n 1989, and three in 1990. Dispensers were placed in trees at a densit y of 1000/ha shortly after apple bloom. Male orientation to pheromone traps was almost totally disrupted (a few males were captured at high population densities). In 1989, the Daleville pheromone-treated block had 0.9% and 0.8% CM-injured fruit in the center and edge, respectivel y; 0% and 39.5% injured fruit were found in the conventional control a nd abandoned blocks, respectively. The Criglersville orchard ('organic ally' managed, with high CM density) CM harvest injury was 16.0%, 16.5 %, 34.5%, and 26.5% in the pheromone-treated center and edge, organic control and abandoned blocks, respectively. In 1990, the Daleville CM harvest injury was 4.7%, 7.3%, 1.1%, 0.3% and 58%, in the pheromone-tr eated center and edge, control center and edge, and abandoned blocks, respectively (possible reasons for the high injury in this block are d iscussed). Harvest injury in the Fincastle pheromone-treated and contr ol blocks were 0.7% and 0%, respectively. The Criglersville orchard yi elded 17%, 19% and 20% CM-injured fruit at harvest in the pheromone-tr eated, organic control and abandoned blocks, respectively. Pheromone r elease rate was calculated as 37 mg/ha/h in 1989.