Apple, Test of Acaricides, 1982

Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 2 replicates of Golden Delicious and 2 Red Delicious, both spur-type trees. Experimental sprays were applied with a spraygun from a truck-mounted hydraulic sprayer. Spray dates were as follows: Apr 29 (Tranide treatment); Jun 8 (all treatments except Tranide); Jun 18 (all treatments except Tranide); and Jul 23 (all treatments except Tranide). General purpose sprays of Captan 50W, Guthion 5QW and Sevin 50W were applied at intervals of ca. 2 weeks throughout the summer. Average temperatures were: May 66 F, June 67 F, Jul 78° F, and Aug 74 F. Rainfall in inches totaled: May 2.45, Jun 6.65, Jul 3.00, and Aug 1.80. Effectiveness of test materials on European red mite was evaluated by several counts of mites on random samples of 25 leaves/tree, 100 leaves/treatment. Mite population pressure was heavy throughout the season. Russeting of Golden Delicious apples was determined by scoring a random sample of 30 apples/replicate, 60 apples/treatment. Fruits were rated as no russeting (1), light russeting (2), moderate russeting (3), and severe russeting (4). Possible ranges were: russeting, none to light 30-60, light to moderate 60-90, and moderate to severe 90-120. All treatments provided good to excellent control of the European red mite except the Tranide treatment and the low rate of NC-21314. The half-rate combination of Carzol plus Plictran gave longer residual control than Carzol alone. Starting with the first treatment, average russet ratings in order are as follows: 98, 100, 98, 88, 101, 99, 108, 94, 98, 110, and 113.