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 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. Approximately 8.0 gallons of spray were applied/replcate tree. Spray dates for test insecticides were: May 25, Jun 6, 20, Jul 6, 25, Aug 9, 10, and 23, On Jul 26, 228 g/acre of Plictran 50W was applied from the east side of all experimental trees. During the season general sprays involving Cyprex, Polyram, captan, sulfur, zlneb, and calcium chloride were applied with an airblast sprayer at 50 gpa to the whole experi mental block. Average temperatures were: May 60.3°F, Jun 66.2°F, Jul 70.8°F, Aug 71.3°F, and Sep 64.3° F. Rainfall in Inches averaged: May 4.03, Jun 2.41, Jul 3.19, Aug 4.88, and Sep 8.99. Effectiveness on the apple aphid was evaluated by counting the number of infested terminals/10 top terminals/tree, the number of aphid infested leaves/terminal, and the number of aphids/most infested leaf/infested terminal. The effect of the sprays on the white apple leafhopper was evaluated by counting the number of nymphs/25 leaves per tree. Effectiveness of the 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 predators, S. punctum and H. vitripennis was evaluated by 3-min counts of adults and larvae and adults and nymphs, respectively, around the periphery of the test trees. Effectiveness of chemicals on fruit feeders was assessed by scoring for injury all drops after Jul 9 and 2 pick samples on Aug 16 and Sep 7. Apple samples averaged 194 fruits/replicate and 776/treatment. Pest pressure was moderate to heavy throughout the season.
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