High versus ultra-low volume spraying of a microencapsulated pheromone formulation for codling moth control in two apple cultivars

Abstract

Mating disruption is the controlled release of sufficiently large quantities of insect sex pheromones into the air, using pheromone dispensers, so as to disrupt the ability of males to locate and mate with females. Current microencapsulated sprayable pheromone formulations for codling moth have limited residual activity, but applying sufficient amount of microcapsules in the canopy can enhance their disruption efficacy. For this purpose, the effect of spray volume and apple cultivar on the number of pheromone microcapsules was studied in 2006 and 2007. Sprayable pheromone was applied at a rate of 25g a.i./ha either in high-volume (768l water/ha) or ultra-low volume (24l water/ha) sprays with an airblast sprayer. The low-volume application deposited significantly more microcapsules per cm2 leaf, which was particularly evident in the upper tree canopy and on the undersides of the leaves. Microcapsule retention also significantly differed between 'Fuji' and 'Granny Smith' fruits treated with low-volume application. Our results suggest that spray volume and pressure reductions can increase the number of microcapsules deposited on leaves and fruits. Varying the leaf and fruit retention characteristics of cultivars may also influence the use of sprayable pheromones in mixed cultivar orchards.