Apple, Secondary Insecticide Testing, 1991

Abstract

Abstract Dilute sprays were applied to runoff with a hand sprayer (32 kg/cm2) at pink (2 May), petal fall (15 May), and as cover sprays on 28 May, 13 Jun, 25 Jun, 12 Jul, 25 Jul, and 8 Aug. In the Penncap M/Danitol and Guthion 35 W/Danitol programs, Danitol was applied alone at pink (2 May), petal fall (15 May), third cover spray (25 Jun), and sixth cover spray (8 Aug), and the organophosphates were applied alone in the other sprays. Treatments were replicated 3 times (two 6-tree plots, 'McIntosh', 'Cortland', 'Rhode Island Greening', 'Monroe', 'Golden Delicious', and 'Red Rome', and one 8-tree plot containing two adjacent 'McIntosh', 'Cortland', 'Golden Delicious', and 'Delicious' trees). Treatments were arranged in a randomized block design. At harvest (12-17 Sep), 100 'McIntosh' and 100 'Cortland' apples were scored from each replication. ERM and predaceous mites were sampled on 25 randomly selected leaves from the 'McIntosh' apple trees in each replication on 7 Jun, 18 Jun, 2 Jul, 22 Jul, 6 Aug, and 22 Aug. Mites were removed from leaves with a Henderson-McBurnie mite brushing machine. On 19 Jun, aphids were counted on the 2 distal leaves on each of 10-60 growing terminals/tree on a single 'McIntosh' tree in each plot and given a logarithmic rating based on the number of aphids per leaf (0 aphids = 0, 1-10 aphids = 1, 11-100 aphids = 2). WALH were counted on 25 randomly selected spur leaves ("Rhode Island Greening' trees in Rep I and II, and 'McIntosh' trees in Rep HI) on 23 Aug. PLH were counted on the 5 distal leaves of 10-60 growing terminals in each plot on 19 Jun. STLM tissue mines were counted on the 6 distal leaves of 20 randomly selected terminals from 'McIntosh' trees on 26 Aug. Fruit finish was evaluated at harvest by rating a sample of 100 randomly selected 'Golden Delicious' apples using a russet rating: 0 = No russet,1 = 0-33% russet, 2 = 34-66% russet, 3 = 67-100% russet.