Control of Fall Webworm on Walnut, 1991

Two separate experiments were conducted on walnut trees, 10-20 ft tall, growing in—n orchard located at the Agricultural Experiment Station in Payne Co. Treatments were applied 28 Jun using a Marco R-20 sprayer which delivered 1.2 gal/ min at 150 psi and were arranged in a randomized complete block design. At the time of treatment, temperature and wind velocity were 81°F and 0-5 Iripil respectively. Measurable precipitation during the test period occurred on 4 Jul (.44 inch). Three rates of the insect growth regulator RH-5992 were evaluated in Test 1. A spreader sticker, Latron B-1956, was added to the IGR treatments at 6 ml/gal of finished spray. Two formulations of chlorpyrifos, Pageant DF, at several rates were evaluated in Test 2. Both tests utilized Orthene 9.4 EC as a standard treatment. The number of FW larvae/nest was determined by removing and dismantling one nest from each treatment in all replicates and assessing the number of live larvae. Test 1 was replicated 5 times and Test 2 contained 4 replications. Both tests were evaluated at 5 and 10 DAT.