Apple, Dilute Test of Insecticides, 1982

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 hydraulic sprayer, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Approximately 8.0 gallons of spray were applied/tree. Dates of application were: May 25, Jun 8 and 22, Jul 6 and 21, Aug 4 and 18, Sept 1. Treatments of Pounce, Ammo, Payoff and Ambush received only Guthion 50WP, 114 g/100 gals on May 25, Jul 6 and 21, and Sept 1. General sprays involving Cypres, Polyram, captan, sulfur, zineb, and calcium chloride were applied with an airblast sprayer at 50 GPA to the whole experimental block. Average temperatures were: May 66°F, Jun 67°F, Jul 78 F, Aug 74 F, and Sept 63 F. Rainfall in inches totaled: May 2.45, Jun 6.65, Jul 3.00, Aug 1.80, and Sept 2.65. Effectiveness on apple aphid was evaluated by counting aphid in fested leaves/10 top terminals, and aphids/most infested leaf/infested terminal. The effect of sprays on white apple leafhopper was evaluated by counting nymphs/25 leaves/tree. Effectiveness of test chemicals on the European red mite and twospotted spider mite was evaluated by counting mites several times during the season on samples of 20 leaves/tree, 80 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 test trees. Effectiveness of chemicals on fruit feeders was assessed by scoring for injury all drops after Jul 1, and 2-pick samples on Aug 17 and Sept 13. Apple samples averaged 188 fruits/replicate and 752/treatment. Pest pressure was moderate throughout the season. Russet ratings are based on 30 Golden Delicious apples/replicate, 60/treatment. No russet (1), light russet (2), moderate russet (3), and severe russet (4). Possible means are: no russet to light russet 30-60, light to moderate russet 60-90, and moderate to severe russet 90-120.