Apple, Dilute Test of Acaricides, 1984

Abstract

Abstract Plots consisted of single trees in a randomized block design with 2 replicates of Golden Delicious and 2 replicates of Delicious, both spur types. Experimental sprays were applied to run-off with a handgun from a truck-mounted John Bean sprayer equipped with a 35 gpm pump. Spray dates were as follows: 2 May (DPX-Y5893 treatments only), 8, 19 Jun (all treatments except DPX-Y5893), 3 Jul (DPX-Y5893 treatments only), 25 Jul (all treatments except DPX-Y5893), 14 Aug (all treatments except DPX-Y5893 and Plictran plus NC-21314). General sprays of fungicides (Cyprex, Benlate, Polyram, Captan, Zineb, Bravo, Rubigan, Manzate, Bayleton, Dithane), insecticides (Lorsban, Phosphamidon, Guthion, Sevin, Pydrin, Systox), and calcium chloride were made at ca. 1 to 2-week intervals throughout the experiment with a Friend Airmaster at 50 gpa. Average temperatures were: May 58.5° F, Jun 70.3° F, Jul 71.3° F, and Aug 72.6° F. Rainfall in inches totaled: May 4.51, Jun 4.42, Jul 5.86, and Aug 7.33. Effectiveness of materials on mites was evaluated by making several counts on random samples of 25 leaves/tree, 100 leaves per treatment. Mite population pressure was severe 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 ratings are in numerical order and are as follows: 35, 37, 41, 35, 37, 38, 47, 37, 38, 41, 37 and 35.