MATING DISRUPTION FOR CONTROLLING THE CODLING MOTH, CYDIA-POMONELLA (L) (LEPIDOPTERA, TORTRICIDAE), IN ORGANIC APPLE PRODUCTION IN SOUTHWESTERN ONTARIO

Sex pheromone-mediated mating disruption using Isomate-C(R) pheromone dispensers was evaluated as a means of controlling the codling moth, C ydia pomonella, over three consecutive growing seasons in organically managed blocks of apples at two commercial apple orchards in Ontario. The objective of the study was to determine if mating disruption could be used to stabilize or reduce the amount of damage caused by indigen ous codling moth populations. The emission rate of the pheromone dispe nsers was estimated using Volumetric and gravimetric methods, Efficacy of the pheromone treatment was assessed by comparing pheromone-baited trap catches of adult male codling moths in pheromone- and insecticid e-treated blocks of apples, and by estimating damage caused by first- and second-generation codling moths in pheromone and insecticide-treat ed blocks as well as in small plots of apples where the codling moth w as not controlled. The estimated average release rate of pheromone var ied from 22.2 to 30.3 mg per ha per h. The seasonal total number of ad ult male moths trapped in the pheromone-treated blocks was from 3.8 to 25.3% of the number trapped in insecticide-treated blocks; during one season at one farm, no moths were trapped in a pheromone-treated bloc k. Treatment with pheromone did not prevent an increase in codling mot h damage. At one farm, damage increased ca. 5-fold during the 3-year s tudy. At the other farm, damage increased ca. 4-fold during two consec utive growing seasons in one block and ca. 4-fold during three consecu tive seasons in the other block. At both farms there was a marked incr ease in the amount of damage between the first and second generations of the pest. Possible reasons for the failure of the pheromone treatme nt to prevent increases in codling moth damage are discussed.