Apple, Dilute Test of Insecticides, 1984

Abstract

Abstract Experimental sprays were applied to run-off to single tree plots in a randomized block design consisting of 4 replicates of Golden Delicious. Treated single trees were separated by others not sprayed with insecticides. Sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying spray guns arranged to wet the uniformly trimmed trees. Approximately 8 gal of spray were applied per replicate tree. Dates of application were: 22 May; 6, 20 Jun; 5, 19 Jul; 2, 16, 30 Aug. Pounce 3.2EC (44 ml/100 gal) was substituted for the Advantage treatments on 22 May. Guthion 50WP (114 g/100 gal) was substituted for the Advantage treatments on 5, 19 Jul. Rates of Advantage were increased to 188 ml and 340 g on 16, 30 Aug. Guthion 50WP (114 g/100 gal) was substituted for Spur on 6 Jun, 2, 16 Aug. During the season general sprays involving Cyprex, Polyram, Benlate, Topsin M, Captan, Zineb, and calcium chloride were applied with an airblast sprayer at 50 gpa to the whole experimental block. Average temperatures were: May 58.5° F, Jun 70.3° F, Jul 71.3° F, Aug 72.6° F and Sep 60.9° F. Rainfall in inches totaled: May 4.51, Jun 4.42, Jul 5.86, Aug 7.33, and Sep 1.11. Effectiveness on AA was evaluated by counting aphid-infested leaves/10 top terminals, and aphids/most infested leaf. Effect jf sprays on WALH was evaluated by counting numphs/25 leaves/tree. Effectiveness of test chemicals on ERM, TSSM and predatory mites was evaluated by counting mites several times during the season on samples of 20 leaves/tree, 80 leaves/treatment. Effect of sprays on SP was evaluated by 3 min counts of adults and larvae around the periphery of the test trees. Effectiveness of chemicals on fruit feeders was assessed by scoring for injury all drops after 1 Jul and 2 picked samples on 23 Aug and 17 Sep. Apple samples averaged 159 fruits/replicate and 636/treatment. Pest pressure was heavy throughout the season. Russet ratings are based on 30 Golden Delicious apples/replicate, 120/treatment. Fruits are 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).