Mating disruption for the control of loaf rollers on apricots

Otago apricots (Prunus armeniaca L.) are damaged by the endemic leafrollers , Planotortrix octo Dugdale and Ctenopseustis obliquana (Walker): and an Au stralian species, Epiphyas postvittana (Walker), all of which are quarantin e pests on export fruit. Mating disruption, using sex pheromones, represent s one promising option for pest management with reduced insecticidal inputs for apricots. Two pheromone blends were used: one, designed to disrupt the two endemic species, was (Z)-5-tetradecenyl acetate and (Z)-8-tetradecenyl acetate, (25:75) and the other, for E. postvittana, was (E)-11-tetradeceny l acetate and (E)-9,(E)-11-tetradecenyl-1 acetate (95:5). No moths of three leafroller species were caught in pheromone traps at the centre of 0.1 ha plots of apricot trees treated with polyethylene tubing dispensers, at 1000 /ha. whereas those outside the treated area (70 m distant) continued to cat ch. In commercial orchards, dispenser blends prevented trap catch and reduc ed damage in apricots on 1-3 orchards per year over 5 years. Dispensers, in secticides, and combinations of the two were equally effective in preventin g damage to the fruit and gave better results than the untreated. Dispenser s were not as effective as an insecticide programme at one large site over 4 years, except in the centre of the block. Dispensers were less effective where the tree canopy cover was incomplete and this effect was more importa nt than the size of the area treated. Apricots were successfully exported f rom a 4.8 ha planting that was protected fi-om leafroller damage by the end emic leafroller pheromone dispensers alone in 1996, and those for E, postvi ttana and the endemic leafrollers (two different dispenser blends) in 1997. Differences between prospects for the use of mating disruption in summerfr uit (stonefruit) and pipfruit (pome fruit) are discussed.