Apple, Insect and Mite Control, 1985

Abstract

Abstract Test materials were applied to 19- to 29-year-old apple trees at Monmouth, Maine, as dilute sprays using a hand gun and a hydraulic sprayer operating at 250 psi at 300 gal/acre. Trees were sprayed on 16 May (pink, P), 28-29 May (petal fall, PF), 14 Jun (first cover, 1C), 25-26 Jun (second cover, 2C), 9 Jul (third cover, 3C), 23-24 Jul (fourth cover, 4C), 6 Aug (fifth cover, 5C), 20 Aug (sixth cover, 6C), as noted in the table; the Rotacide treatment (3C-9C) was applied only on 9 Jul, 17 Jul, 25 Jul, 2 Aug, 8 Aug, 15 Aug, and 22 Aug. The fungicide program consisted of Difolatan 4F (5 qt/100) on 24-28 Apr and Polyram 80W (2 lb) which was mixed with each insecticide treatment at each spray date; no Polyram mixtures were made with the Rotacide treatment (3C-9C). There were 3-4 single tree applications for each treatment. A randomized complete block design was used with 2 ‘Mcintosh’ and 2 ‘Cortland’ cultivars in Test 1 and 4 ‘Mcintosh’ in Test 2. Except for test trees, the orchards were not sprayed with insecticides. On 28 Aug, 0.5 box of apples was picked from each tree (only 3 trees were sampled in Test 2), and about 520 (Test 1) or 180-370 (Test 2) apples were examinee1 per treatment on 7 to 14 Sep for external egg punctures (AM), egg-laying scars (PC), and typical feeding injuries (CM, LAW, and TPB). ERM were counted on 31 Jul and 15-16 Aug on 25 leaves collected at chest-height around the periphery of each tree. Leaves were brought into the laboratory and brushec onto glass plates coated with a Tween 20 and alcohol mixture; mites were counted the same day. Aphid counts are based on 10 randomly selected vegetative terminals around each tree. Numbers of live aphids on the distal 4 unfurled and 1 furled leaves and on the stem included by these leaves were recorded or 18 Jul and 1 Aug (Test 2). May and Jun were cool, the first half of Jul was wet (3.9 inches rain), and Aug was wetter (3.4 inches rain) and cooler than normal.