California Red Scale Pesticide Efficacy Trial, 1992

Abstract

Insecticides for the control of CRS were evaluated spring, 1991 in Field 63 (18-yr-old Fisher and Washington navel oranges) located at the University of California’s Lindcove Field Station near Exeter, Calif. Insecticides were applied with a Bean handsprayer at 400 psi, complete coverage, approximately 1500 gpa. The field was divided into 10 blocks with one replicate of each treatment applied to a single tree within each block. Treatment trees were separated on all sides by single untreated trees. Five twig samples (gray wood indicating 2nd year growth, 23 cm in length) and 5 fruit were collected randomly from each of the sample trees and examined for 1st stage, 2nd stage, virgin and mature female stages of scale. Scale on the fruit were also examined for live larvae and pupae of C. bifasciata and eggs, larvae and pupae of A. melinus. Twig samples were collected pretreatment and both twig and fruit samples were collected 30 and 60 DAT. Leaf drop was measured weekly by counting the leaves that collected on a 60 X 90 cm paper tray placed under the canopy in the north side of treatment trees in five of the blocks. The population of the predatory mite, E. tularensis, was determined by collecting 20 leaves per tree (5 per quadrant) each week in 5 of the blocks until 60 DAT. Foliar treatments were applied on 14-15 May during the first generation of CRS crawler activity while the fruit was less than 20 mm in size.