Apple, Dilute Test of Acaricides, 1986

Plots consisted of single trees in a randomized block design with 2 replicates of Golden Delicious and 2 replicates of York Imperial, both spur types. Trees were planted to a spacing of 6.1 × 10.7 m. 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 5.0 gallons of spray were applied per replicate tree. Spray dates were as follows: 25 Apr (Morestan and ABG-6162 alone treatments), 6 May (ABG-6162, Apollo alone, PH 70-23 treatments), 3 Jun (Kelthane, BAS 276001, Omite, Plictran treatments), 5 Jun (R0 08-4947 treatments), 18 Jun and 16 Jul (all treatments), 4 Aug (Savey, low rate of ABG-6162, Kelthane 4F, Omite, Plictran treatments). Morestan was applied only on 25 Apr. Apollo alone was applied only on 6 May. General sprays of fungicides (Cyprex, Benlate, Polyram, Manzate, Bayleton, Dithane), insecticides (Lorsban, Phosphamidon, Guthion, Sevin, Pydrin, Systox), and calcium chloride were made at ca. one-to two-week intervals throughout the experiment with a Friend Airmaster at 50 gal/acre. Effectiveness of materials on mites was evaluated by making several counts on random samples of 25 leaves/tree, 100 leaves/treatment. Cumulative number of mite days were calculated as the mean of two successive counts multipled by the number of intervening days, and summed over the season. Mite population pressure was heavy 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). The russet ratings for treatments as listed in tables are as follows: 67, 58, 72, 68, 58, 54, 69, 64, 68, 70, 67, 84, 90, 82, 69, 57, 73.