EVALUATION OF TREATMENTS FOR THE CONTROL OF ONION THRIPS DAMAGE TO CABBAGE, 2008

This test is an ongoing effort to screen new insecticides against destructive onion thrips on cabbage. ‘Tobia’ cabbage, a known thrips-susceptible variety, was transplanted at the NYSAES Fruit and Vegetable Research Farm near Geneva, NY on 20 Jun. Plots consisted of 2 adjacent rows: 1 border row and 1 treated row. Blocks consisted of seventeen 20 ft. rows to accommodate 7 treatments and 1 untreated check at 30-inch row spacing and 18-inch in-row spacing, and were replicated four times in a RCB design. For foliar sprays, a CO2 backpack sprayer was used for application of treatments with a onerow boom consisting of three nozzles per row (one nozzle over the top and one drop nozzle on each side) using TeeJet XR8002VS nozzles delivering 40 gpa at 40 psi and 2.7 mph. Seven weekly treatments were applied starting 5 wk posttransplanting. Foliar applications were made on 28 Jul, 4, 12, 19, 26 Aug, and 2 and 9 Sept. The surfactant ‘Induce’ was added to all treatments at the rate of 2.5 ml/L. Approximately 4 wk post-transplanting, the AdmirePro 2F treatment was applied using the CO2 backpack sprayer with a boom consisting of a single nozzle (TeeJet XR8003VS) delivering 30 gpa at 40 psi and 2 mph. The spray was directed at the base of the plant. All plots were treated with Dipel at 1.0 lbs/acre on 9 August to prevent injury from lepidopteran feeding. Harvest evaluations for thrips damage were made on 22 Sep and consisted of harvesting 3 mature heads per treatment, cutting them in half along the core and peeling back the first 10 layers of one half and noting the presence and degree of thrips damage to each layer. We used two methods to compare treatments: the average number of layers per 3 heads in a replicate and the average damage rating per 3 heads in a replicate. The damage rating was on a scale of 0 (no damage) to 4 (all 10 layers with severe damage). Data were analyzed using GLM PROC in SPSS for Windows and Fisher’s protected LSD means separation test.