Pear, Laboratory Screening of Pesticides Against Grape Mealybug, 1992

Candidate pesticides were applied as topical sprays in a Potter spray tower to overwintering crawler-stage nymphs collected from commercial pear orchards in the Wenatchee area. Five serial dilutions and a water control were applied to two replications of 10 crawlers held in 50 X 9 mm Petri dishes. After 48 h exposure the number of dead crawlers was determined with the aid of 15 X magnification. Diazinon, the standard treatment used in commercial pear orchards, was tested against two populations; one from an orchard where this material had not provided control in 1991, the other from a pear block on the Research Center that had not been treated with insecticides during the last 20 yr. All other materials were tested against the population from the commercial orchard. Percent kill was corrected for mortality in water controls using Abbott's formula.