Pear, Residual Control of Pear Psylla, 1987

Abstract

Abstract Mature Bartlett pear trees were sprayed with a handgun operating at 600 psi to evaluate residual life of Abamectin and amitraz for control of pear psylla nymphs. Leaves were collected from trees at intervals after applications. Ten circular disks, 2.2 cm diam, were punched from leaves and floated on wet paper towels in 15-cm plastic Petri dishes for each treatment at each postapplication interval. Ten PP nymphs were transferred to each disk. Petri dishes containing infested leaf disks were held in a growth room at 25°C and 16:8 (L:D) photoperiod. Treatments were evaluated by counting dead and live nymphs after 72 h exposure on the disks. Tests were conducted with leaves collected 1, 3, 7, 10, and 14 days after sprays were applied for the 4 May test but only 1, 7, and 14 days after sprays for the 8 and 29 Jun tests. To test toxicity of growing terminal;- to adult PP, shoots were collected from each treatment and the control 17 days after applications for the 4 May test and 1, 7, and 14 days after sprays foi the 8 and 29 Jun tests. Test shoots were placed upright in sand in clay pots. The pots were placed in a tray containing 2 inches of water to keep shoots turgid. Twenty-five summer-form adult PP were caged on each shoot for 3 to 6 days then surviving adults and eggs were counted. An intense, short rain shower occurred about 30 min after the 8 Jun application.