Apple ,Test of Insecticides, 1980

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 John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Approximately 8.0 gallons of spray were applied per replicate tree. Dates of application were as follows: Temik treatments applied only once by hand on May 13; both amitraz treatments (no Guthion) applied on May 22; Jun 5 Guthion only on 1st amitraz treatment, amitraz only on 2nd treatment (Guthion only then applied on remaining spray dates to both treatments); all other treatments. May 23, Jun 10 and 24, Jul 9 and 23, Aug 6 and 21. During the season general sprays involving Cyprex, 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 61.5° F, Jun 66.5° F, Jul 74.9° F, Aug 76.3° F and Sep 65.5° F. Rainfall in inches averaged: May 4.49, Jun 4.02, Jul 1.48, Aug 1.71 and Sep 1.53. Effectiveness on the apple aphid was evaluated by counting the number of infested terminals/100 top terminals/tree, the number of aphid infested leaves/terminal, and the number of aphlds/most infested leaf/infested terminal. The effect of the sprays on the white apple leafhopper was evaluated by counting the number of nymphs/25 leaves/tree. Effectiveness of the test chemicals on the European red mite was evaluated by counting the mites several times during the season on samples of 15 leaves/tree, 60 leaves/treatment. The effect of sprays on the predators S.punctum and H.vitripennis was evaluated by 3-minute counts of adults and larvae and adults and nymphs, respectively, around the periphery of the test trees. Effectiveness of chemicals on fruit feeders was assessed by scoring for injury all drops after Jul 17 and 2 picked samples on Aug 19 and Sep 3. Apple samples averaged 240 fruits/replicate and 960/treatment. Pest pressure was moderate throughout the season. Russet ratings are based on 30 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.