Walnut Husk Fly Control with Bait Sprays, California, 1979

Field experiments were carried out in a 6-acre mature walnut planting of the Franquette variety to evaluate the synthetic pyrethroid Pydrin with and without a protein hydrolysate bait for control of husk fly. Four treatments (including the check), each consisting of four 6-tree (2 × 3) replicates, were arranged in a randomized complete block design. Treatments varied from full tree coverage without bait to 1/2 and 1/4 tree coverage with bait sprays. All applications were made with a hydraulic handgun sprayer. Shortly before harvest (Oct 10) nuts (2400/treatment) were inspected for husk fly eggs, larvae, and shell stains. Leaf samples (480 leaflets/treatment) were taken Oct 25 and brushed for mites.