Control of Sweetpotato Whitefly on Fall Broccoli, 1993

Abstract

Abstract Broccoli was direct seeded on 22 Sep into double row beds on 40 inches centers at the University of Arizona Yuma Agricultural Center. Plots consisted of 4 beds, 50 feet long with a two bed buffer between the plots. Plot preparation and seasonal maintenance followed local practices. Plots were arranged in a randomized complete block design with four replications. Foliar sprays were applied using a tractor-mounted sprayer which delivered 60 gpa at 300 psi. The spray boom covered four beds with two nozzles (TX08 hollow cone) per bed suspended from the boom. A spreader/sticker (Dynamic) was applied at 0.5% v/v in all treatments. Foliar applications were initiated when immature whitefly densities reached measurable levels and were made on 13, 20, 28 Oct and 9 Nov. Admire and CGA215944 were applied to the seed bed at planting (22 Sep) with a 2 inch band application delivering 15 GPA directly over the seed line and immediately followed by sprinkler irrigation. The CGA 215944 treatment also received foliar sprays of CGA 215944 on 13, 20, 28 Oct and 9 Nov. Insect data were collected only from the inner two beds of each plot. Immature SPWF densities were estimated weekly by counting total immatures on four-2.5 cm2 leaf disks from each of 10 leaves per plot. Adults were assessed by collecting adults from plants with a modified Vacuum collector. Data were log transformed (log10 + 1) before analysis of variance, and treatment differences were estimated with Ryan’s Q-test.