Diflubenzuron-Based Management of the Pear Pest Complex in Commercial Orchards of the Hood River Valley in Oregon

Abstract

In the Hood River Valley of Oregon, a pear pest management program based on the insect growth regulator, diflubenzuron, was compared with conventional programs based on broad-spectrum pesticides during 1987-1989. Diflubenzuron-based programs allowed for the immigration and development of natural enemies of the pear psylla, Cacopsylla pyricola Forster. In 13 of 14 comparisons, natural enemies were more abundant in diflubenzuron-based plots than in conventional plots, but additional psyllacides were almost always required to prevent unacceptable fruit damage. Psylla densities were determined by both pesticide applications and seasonal predator-prey interactions. Psylla densities were lower in plots where a light oil was added to the first 2 diflubenzuron applications. Codling moth, Cydia pomonella (L.), were suppressed effectively in both diflubenzuron-based and conventional plots. Miticides were frequently required in all plots, conventional or otherwise, but mites were suppressed best in plots where diflubenzuron with oil was applied. Densities of predatory mites were low at all sites during all years.