Seasonal Insecticide Evaluation, 1988

Abstract

Abstract 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 planted to a spacing of 20 x 35 ft. Sprays were applied with a John Bean sprayer, 35 gal/min pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees (400 gal/acre). Approximately 6.2 gal of spray were applied to each replicate tree. Dates of application were 25 Apr (first RH-5849 treatment only); 23 May; 7 and 21 Jun; 6 and 20 Jul; and 3, 17, and 31 Aug. Effectiveness against the aphid complex was evaluated by counting the aphid-infested leaves/10 top terminals and the aphids on the most infested leaf. The effect of the sprays on WALH was evaluated by counting the nymphs on 25 leaves/tree. Effectiveness of the test chemicals against ERM, TSSM, and predatory mites 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. punctutn was evaluated by 3-min counts of adults and larvae around the periphery of the test trees. STLM was evaluated by a 5-min count of mines around the periphery of the test trees. The effectiveness of chemicals against fruit feeders was assessed by scoring for injury all drops after 1 Jul and 2 samples picked on 22 Aug and 19 Sep. Apple samples average 194 fruits/replicate and 776/treatment. 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).