Aphicide Evaluation, 1988

Experimental sprays were applied to run-off to single-tree plots in a randomized block design consisting of 2 replicates of ‘Golden Delicious’ and 2 replicates of ‘Yorking.’ Treated single trees were separated by others not sprayed with insecticides. The trees were 5 yr old and planted to a spacing of 20 X 30 ft. Sprays were applied with a John Bean sprayer, 35 gal/min pump, equipped with a handgun. Approximately 2.6 gal of spray was applied per replicate tree (190 gal/acre). Dates of application were 23 May, 10 and 23 Jun, and 22 Jul. All plots were oversprayed with Imidan and Dithane biweekly. Effectiveness on the aphid complex was evaluated by counting aphid-infested leaves/10 top terminals, and aphids/most infested leaf. The effect of the sprays on WALH was evaluated by counting the nymphs on 25 leaves/tree. The effect of the test chemicals on ERM, TSSM, and ZM was evaluated by counting the mites several times during the season on samples of 25 leaves/tree, 100 leaves/treatment. The effect of sprays on S. punctum was evaluated by 3-min counts of adults and larvae around the periphery of the test trees. Russet ratings are based on 30 ‘Golden Delicious’ apples/replicate, 60/treatment. Fruits were rated as 1 (no russeting), 2 (light russeting), 3 (moderate russeting), or 4 (severe russeting). Possible ranges were 30-60 (none to light), 60-90 (light to moderate), 90-120 (moderate to severe).