CHEMICAL CONTROL OF MALE SAN JOSE SCALE (HOMOPTERA: DIASPIDIDAE) IN APPLES, PEARS, AND PEACHES

Chemical treatments to kill male San Jose scale, Quadraspidiotus perniciosus (Comstock), were applied to apples, pears, and peaches in Washington, Oregon, and California respectively. Dilute sprays of diazinon applied just prior to or at first emergence of overwintered males and 7 or 14 days thereafter were compared with normal sprays directed against scale crawlers. In all instances, treatments for male scale gave control equal to that provided by a single spray timed to control first generation crawlers.Although the male sprays were effective, they do not fit well into current pest management programs. Complications with the male sprays included timing that coincided with petal fall on earlier varieties or full bloom on later varieties with potential for kill of pollinators; possible disruption of adult predators stressed by overwintering, and russeting of Golden Delicious apples from immediate post-bloom sprays. In all three crops, post-bloom male sprays would also be an added seasonal treatment. Current practices utilize pre-bloom sprays, or combine scale crawler control with sprays for codling moth, Laspeyresia pomonella (L.), peach twig borer, Anarsia lineateila Zeller, and/or mites in June.