Apple, Evaluation of Experimental Miticides, 1991

Abstract

Abstract Treatments were applied to 7 tree plots replicated 4 times in a randomized complete block design. The orchard block consisted of 'Empire', 'Red Delicious', and 'Rome' on M7a, planted in 1982 on a 15 by 18 ft spacing. Replicates 1 and 2 were on 'Red Delicious', while replicates 3 and 4 were on 'Empire'. Sprays were applied with an FMC handgun sprayer using a 5 HP diaphragm pump at 280 psi until run off, with approx. 4 gal of spray applied to each tree. One application of Pydrin 2.4 EC 178 ml/100 gal was made on 6 Jun in order to build mite populations, since few mites were present early in the season. Miticides were applied on 1 Jul and again on 10 Jul. Conditions during applications were 75°F on both dates, with 2 mph winds and cloudy skies on 1 Jul, and 2-4 mph winds and clear skies on 10 Jul. Treatments were as follows: 1) BAS 300 00 I 20 WP .05 lb AI/100 gal, 2) BAS 300 00 I 20 WP . 12 lb AI/100 gal, 3) BAS 300 11 I 75 WP .05 lb AI/100 gal, 4) BAS 300 11 I 75 WP . 12 lb AI/100 gal, 5) Omite (propargite) 30 WP .60 lb AI/100 gal, and 6) Omite 30 WP .30 lb AI/100 gal, 7) Untreated. ERM counts were taken in samples of 15 leaves per tree on 7 Jun (pre-treatment), and again on 3, 8, 15, 22, 29 Jul, and 5, 12 Aug. SP populations were evaluated on 12 Aug. Predacious mites and beetles were not present early in the season, since they had been eliminated by the Pydrin application. Fruit finish was evaluated by taking 30 fruit from each tree and evaluating for fruit russet on a 0 to 5 basis. Values were used as follows: 0 = no russet, 1 = raised lenticels, 2 = 1-10% russeted, 3 = 11-15% russeted, 4 = 16-50% russeted, and 5 = >51% russeted. Each fruit was evaluated, and an average per replicate was used in the calculations.