Insect and Mite Control, 1990

Abstract

Abstract Test materials were applied to 34-yr-old apple trees at Monmouth, Maine, as dilute sprays by handgun and hydraulic sprayer operating at 250 psi at 370 gal/acre. Trees were sprayed on 15 May (pink [P]), 7 Jun (petal fall [PF]), 15 Jun (first cover [IC]), 26 Jun (second cover [2C]), 10 Jul (third cover [3C]), 24 Jul (fourth cover [4C]), 6 Aug (fifth cover [5C]), and 21 Aug (sixth cover [6C]), as noted in the table. The standard pesticide program consisted of Thiram 65 W (2.0 lb/100 gal) on 7 dates and Nova 40 W (2.5 oz) on 5 dates. There were no mixtures of insecticides with other pesticides. There were 4 single-tree replications for each treatment. A randomized complete block design was used with 2 'Red Delicious' and 2 'Cortland' cultivars. Except for test trees, the orchard was not sprayed with insecticides or acaricides. On 28 Aug, 420 apples were picked from the 4 trees of each treatment and examined on 9 and 15 Sep for external egg punctures (AM), egg-laying scars (PC), and typical feeding injuries (CM and LAW). ERM were counted on 25 leaves collected at chest-height around the periphery of each tree. Leaves were brought into the laboratory and brushed onto glass plates coated with a Tween 20 and alcohol mixture; mites were counted with the same day. There was adequate and normal rainfall during May, Jun, and Jul, with slightly less in Aug. The summer months were slightly warmer and more humid than normal.