Apple, Airblast Acaricide Evaluation, 1983

Acaricides were applied at various times to manage ERM in conjunction with its predators, S.punctum. Each treatment was applied to single 8-yr-old trees in a randomized block design consisting of two replicates of Stayman and three replicates of ‘Delicious.’ Treatments were applied with an airblast sprayer at 25 gal/acre per alternate side driven at 2 mph. Rates for treatments are listed as amounts per acre per both sides spray. Spray dates for alternate side treatments were 27 and 29 Apr. (NC-21314 treatments), 28 Jun. and 7 Jun. (all Kelthane and Plictran treatments), 13 Jul. (NC-21314 treatments), and 19 Jul. (NC-21314, low rate of Kelthane, and Plictran treatments). In the 27 and 29 Apr., and 28 Jun. sprays an error in calibration resulted in 16% less material applied. Fungicides and insecticides applied during the season were: Cyprex, Topsin M, Captan, Zineb, and Lorsban. Average temperatures were: Apr. 47°F, May 57°F, Jun. 68°F, Jul. 74°F, Aug. 72°F. Rainfall in inches totaled: Apr. 8.18, May 4.98, Jun. 4.42, Jul. 0.83, Aug. 2.01. Effects of treatments on ERM were evaluated by counting mites several times during the season from samples of 25 leaves per tree, 125 leaves per treatment. The predator S.punctum was observed by 3-min counts of adults and larvae around the periphery of test trees. Pest pressure was moderate throughout the season.