Apple, Test of Insecticides, 1975

Abstract

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 2 replicates of York Imperial and 2 Golden Delicious. Treated single-trees were separated by others not sprayed with insecticides. Experimental sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Spray dates for the test insecticides were: June 2, 16, 30 and July 1, 15, and 28, August 11 and 25; Pirimor was applied only on June 2, July 25 and August 11; Dimilin was applied only on June 2, June 30, July 28 and August 25; S-15126 was applied only on August 11 and 25 after Stethoruspunctum populations were established in the trees. The following special sprays were applied to the test trees: June 13, Phosphamidon 8, 8 fl oz/100 gal (6X concentrate) with an airblast sprayer; June 19, Systox 6, 4 fl oz/100 gal (IX dilute) with a spray gun; August 14 Plictran 50W, 8 oz/100 gal (6X concentrate) with an airblast sprayer (East of tree's side only). During May, June, July and August, general sprays involving captan and sulfur were applied as 6X concentrates with an airblast sprayer to the whole experimental block at ca. 2 week intervals. Average temperatures were: May 61.08° F, June 68.98° F, July 72.97° F, August 73.89°F, and September 61.13° F. Rainfall in inches averaged: May 4.05, June 7.60, July 3.12, August 2.01 and September 13.84. Effectiveness of test chemicals on the European red mite was evaluated by counting the mites several times during the season on samples of 15 leaves/tree, 60 leaves/treatment. The effect of sprays on the predator S.punctum was evaluated by 3 minute 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 July 1 and a picked sample 14 days after the last spray. Apple samples averaged 230 fruits/replicate and 920/treahnent. Effectiveness on the white apple leafhopper was evaluated by counting nymphs on the underside of 25 leaves/replicate for both generations; on the apple aphid by counting the number of infested terminals/10 terminals/tree and calculating the percent infested. The number of aphid infested leaves/terminal was also determined. The effectiveness of the test materials on the rosy apple aphid was assessed by collecting 10 infested clusters/replicate and determining the percent infested leaves/cluster, the percent leaves with 1-10 live aphids, and the percent leaves with 11 or more live aphids.