Pear, Pear Psylla Control, 1978

Abstract

Abstract Experiments were conducted in a 1.5-acre planting of 6-yr-old ‘d-Anjou’ pear trees. Dilute sprays were applied to single-tree plots with a hand gun and hydraulic sprayer operating at 400 psi. Unsprayed trees were alternated with treated trees within rows. Experiment 1 (Table 1) consisted of 6 prebloom treatments, 5 of which were miscible oil-insecticide combinations, applied Apr 18 (budburst) and Apr 25 (clusterbud). Single-tree plots were replicated 6 times in a complete randomized-block design. Effects of the treatments on pear psylla were evaluated by taking 5 spur leaf clusters at random from each plot and examining them with a stereo microscope. The numbers of eggs and nymphs per sample were recorded. Experiment 2 (Table 2) consisted of 4 treatments applied at petal fall (May 19). Single-tree plots were replicated 6 times in a complete randomized-block design. The plots which received prebloom treatments of Perthane + oil and mancozeb on Apr 18 and 25 were also included in this evaluation. May 18 and 24 counts of psylla eggs and nymps again were made by removing 5 spur leaf clusters from each plot and examining them with a stereo microscope. Counts of eggs and nymphs on Jun 6 were made from 10 leaves taken at random from growing terminal shoots of each plot. Adult pear psylla were sampled Jun 7 by counting the number that were jarred from 3 branches/tree onto an 18-inch square cloth-covered tray. Experiment 3: (Cover spray treatments) Fourteen treatments were applied to single-tree plots replicated 5 times each in a complete randomized-block design. Treatmgits were applied Jun 20 (Table 3), Jul 6 (Table 4), and Aug 17 (Table 5), with the exception of the two Pydrin treatments which were not reapplied on Aug 17. Counts of psylla eggs and nymphs were made from 10 leaves collected randomly from 10 shoot terminals/per plot. Adults were again sampled with an 18-inch square beating tray. All data were subjected to analysis of variance and were grouped using the Waller-Duncan K-ratio t test or DMRT.