Control of Insects and Mites on Fruit Trees by Trunk Injections

Abstract

In greenhouse tests with the two-spotted spider mite, Tetranychus telarius (L.), the antibiotics cytovirin, cycloheximide, and streptovitacin A were effective when injected into peach seedling stems and sprayed on leaves. Cyclohcximidc was not effective when sprayed on trunks and limbs of peach seedlings or applied in bands of paste on limbs of mature apple trees. Trunk injections and foliar sprays of cycloheximide were effective also against peach silver mite, Aculus cornutus (Banks). Solutions of such water-soluble compounds as trichlorfon and methyl demeton moved rapidly to leaves of pear and cherry trees and gave good control of two-spotted spider mite. Water-insoluble compounds moved to leaves of cherry trees when injected in trunks in emulsions and in solution in dimethyl sulfoxide and some other solvents. Many solvents and solutions were phytotoxic at dosages used and caused considerable streaking or uneven distribution in different tree limbs owing to a much more rapid longitudinal than cross movement of materials from the injection site. Distribution was not improved when solutions were injected into a large tree root. Good control of pear psylla, Psylla pyricola Forster, was obtained in biotests of adults on pear leaves 2 weeks after trees were injected with Bidrin® (3-hydroxy-N,N-dimethyl- cis -croton-arnide dimethyl phosphate) and Bayer 47043 (O,O-dimethyl-S- (N,N'-dimethylmalonicamide) thiophosphate). Trunk injections of dimethoate emulsions and some water solutions of other compounds gave control of the green peach aphid, Myzus persicae (Sulzer), the apple aphid, Aphis pomi DeGeer, and the woolly apple aphid, Eriosoma lanigerum (Hausmann).