Apple, Evaluation of Insecticides on Indirect Pests, 1996

Abstract

Abstract Experimental sprays were applied to single-tree plots in a randomized block design consisting of 4 replicates of ‘Yorking’. Treated single trees were separated by others not sprayed with insecticides. The trees were 8 years old and planted at a spacing of 20 x 30 ft. All treatments were applied with a Myers Mity Mist sprayer calibrated to deliver 100 gpa driven at 2.4 mph. All plots recieved a regular fungicide maintenance schedule of Benlate 50DF, Dithane 75DF, Nova 40WP and Ziram 76WP and the insecticide Imidan 70WP. All maintenance materials were applied using the alternate row middle method of application. The effect of the sprays on WALH was evaluated by counting the number of nymphs/25 injured leaves/tree. Effectiveness on the spirea aphid was evaluated by counting the number of aphid-infested leaves/10 top terminals, and by rating the density of aphids/most infested leaf on 0-4 scale as explained in the table footnotes. The number of natural enemies of aphids was determined by counting the number observed on 10 growing shoots per tree. Effectiveness of the test chemicals on ERM was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 100 leaves/treatment. The predator, S. punctum, was observed by making 3-min counts of adults and larvae around the periphery of the trees. STLM was evaluated by a 5-min count of tissue-feeding mines around the periphery of the trees at the end of the 1st and 2nd generations. Also, STLM parasitism was evaluated at the end of the second generation by collecting 25 random leaves/tree and dissecting the mines found. Pest pressure was moderate throughout the season.