Dilute Acaricide Evaluation Experiment, 1989

Abstract

Abstract Plots consisted of single trees in a randomized block design with 1 replicate of'Golden Delicious' and 3 replicates of 'Yorking'. The trees were planted to a spacing of 20 × 20 ft. and were 16-yr-oldv Experimental sprays were applied to run-off with a handgun from a truck-mounted John Bean sprayer equipped with a 35 gal/min pump. Approximately 4.8 gal of spray were applied/replicate tree (ca. 500 gal/acre). Spray dates were as follows: 6 Apr (Oil treatment only), 25 May (Andalin treatments only), 14 Jul (Kelthane treatment only), 27 Jul (Omite and Kelthane treatments only). Omite 6 E was substituted for Andalin on 27 Jul. General sprays of fungicides (Nova, Dithane M-45), insecticides (Guthion, Sevin, Asana), and calcium chloride were made at ca. 1- to 2-wk intervals throughout the experiment with a Friend Airmaster at 50 gal/acre. Effectiveness of the materials on the mites was evaluated by making several counts on random samples of 25 leaves/tree, 100 leaves/treatment. The effect of sprays on the mite predator S. punctum was evaluated by 3 min counts of adults and larvae around the periphery of the test trees. Mite population pressure was moderate throughout the summer. Russet ratings are based on 30 Golden Delicious apples/replicate, 60/treatment. Fruits were 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).