Apple, Test of Insecticides, 1973

Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 3 replicates of Golden Delicious and 2 York Imperial. 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 test insecticides were: May 17, May 31 (June 1 for diazinon), June 15, July 2 and 16, August 2 and 20. During May, June and July, 2 lb Polyram 80W/acre was applied to the whole block at ca. 2 week intervals with an airblastsprayer; in August 2 sprays of 1 lb captan 80W plus 1 lb Polyram 80W/acre were applied similarly. Average temperatures were: May 56.63° F, June 71.30°F, July 73.32°F, and August 73.53°F. Rainfall in inches was: May 6.24, June 5.04, July 2.03, and August 4.57. Effecti veness of test chemicals on the European red mite was evaluated by making 3 counts of mites on samples of 20 leaves/tree, 100 leaves/treatment. The effect of sprays on the predator Stethoruspunctum was evaluated by 3 minute counts of adults and larvae around the periphery of the test trees. Effectiveness of chemicals on fruit feeders was evaluated by scoring for injury all drops after July 1 and a picked sample 15 days after the last spray from 3 replicates of Golden Delicious and 2 replicates of York Imperial. Apple samples averaged 239 fruits/replicate and 1,195/ treatment. Effectiveness on the white apple leafhopper was evaluated by counting numphs on the underside of the leaves for both generations; on the apple aphid by counting the number of infested terminals/10 terminals/tree and calculating the percent infested. Another method was to count the number of aphid infested leaves/terminal.