Isomate C Plus Dispensers as an Alternative Means for Control of Codling Moth, Cydia pomonella L., in Apple Orchards of Bulgaria

Abstract: In the years 2006-2008, trials on the control of codling moth (CM) by mating disruption (MD) using Isomate C plus dispensers were carried out in an isolated 1-ha apple orchard in South-East Bulgaria. Dispensers were hung in the upper third of tree canopies at a density of 1000 pieces per ha before CM flights started. Dynamics of CM flights was monitored by pheromone traps installed in the trial plot and in a conventionally treated reference orchard. Fruit infestation was periodically assessed till harvest time. Hibernating population of CM was estimated in autumn by counting diapausing CM larvae in corrugated cardboard bands. In each of the years, Isomate C plus dispensers completely inhibited CM captures in pheromone traps in the trial plot. Fruit damage remained at low levels till late July and increased slightly only in August. At harvest the percentage of damaged fruits was below 1%. The hibernating population also stayed at low level. In the reference orchard, in spite of numerous chemical treatments, the final fruit damage was high (5.5-28.4%), apparently due to resistance of CM to insecticides. It has been concluded that mating disruption may serve as an alternative means for control of codling moth in Bulgarian apple orchards. Contrary to reports from other countries, this study has shown that good results from MD can be obtained even on a small-size plot, if isolated from external sources of infestation and if initial CM population is low.