Walnut Husk Fly (WHF): Rhagoletis completa (Cresson) This trial was designed to evaluate the efficacy of new reduced risk insecticides as possible replacements for the grower standard organophosphate insecticides. The trial was conducted on mature 'Hartley' cultivar walnut trees in a commercial orchard near Hollister, CA. Nine treatments were replicated four times in a RCB design. Each replicate consisted of an individual tree. Treatments were applied with a hand-held orchard sprayer operating

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... t 200 psi and delivering a finished spray volume of 300 gal/acre. The first applications were applied on 21 Jul after trap capture increase with subsequent applications applied at about three-week intervals on 14 Aug and 3 Sep. Twenty-five nuts per replicate were examined on 11 Sep and 29 Sep on the tree for external signs of WHF larvae infestation. WHF infestation was categorized into ovipositional scar "sting" 1 = larval feeding less than 1.3 centimeters in diameter of the husk, 2 = larval feeding that may be entire husk but no exit holes and 3 = larval feeding that may be entire husk but exit holes present. Adult WHF were monitored with an ammonia carbonate "Supercharged" yellow apple maggot panel trap. The trap was monitored at about 7 day intervals and the trap and ammonia carbonate bait were replaced at monthly intervals or sooner if required. Data were analyzed using ANOVA and means were separated using Fisher's protectected LSD (P ≤ 0.05).