Comparison of pheromone application rates, point source densities, and dispensing methods for mating disruption of tufted apple bud moth (Lepidoptera: Tortricidae)

Small-plot (approximate to 0.1 ha) studies were used to evaluate different pheromone dispensing systems, application rates, and point-source densities for mating disruption of the tufted apple bud moth, Platynota idaeusalis ( Walker). Using polyvinyl chloride spirals impregnated with tufted apple bud moth pheromone (1:1 ratio of E11-tetradecenyl alcohol/E11-tetradecenyl ace tate), pheromone rates of greater than or equal to 1,482 spirals per hectar e (74.1 g pheromone per hectare) were superior to a rate of 988 spirals per hectare (49.4 g pheromone per hectare) in decreasing male response to pher omone traps in 1995, whereas no differences were detected among rates of 98 8, 1,482 and 1,975 spirals per hectare in 1996. Within a range of 370-988 p heromone dispensers per hectare, point source densities were equally effect ive in suppressing male response to pheromone traps. Pheromone-impregnated paraffin disks were equally effective at inhibiting male response to pherom one traps compared with polyvinyl chloride spirals. However, a paraffin emu lsion formulation of pheromone applied with a hand-held grease gun provided longer residual communication disruption effects than polyvinyl chloride s pirals. Dilution of paraffin emulsion pheromone formulations in water for a pplication with a backpack sprayer and airblast sprayer rendered them ineff ective in reducing male response to pheromone traps. The releases of pherom one from polyvinyl chloride spirals and paraffin disks aged in the field we re described by a linear and negative logarithmic curve, respectively, indi cating that dispenser life time should be longer for spirals. The ratio of acetate to alcohol components of pheromone released from spirals increased over time, whereas the release ratio remained more constant for paraffin di sks. This suggests that the disruption efficacy of spirals may be premature ly, reduced because of imbalance of the released components.