Management of Whiteflies and Armyworm on Fresh Market Tomatoes, Fall 1995

Abstract

Abstract Transplants were set 13 Sept, 18 inches apart on raised beds of EauGallie fine sand covered with black polyethylene mulch. Plots were 3-18 ft long rows on 5-ft centers and were irri-gated by a seepage subirrigation system. Insecticidal treatments were replicated 4 times in a RCB design. Spray treatments were applied with a high clearance, self-propelled sprayer on 27 Sept, 11, 18, 25 Oct, 1, 8, 15, 22, 29 Nov, 6, 13 and 20 Dec. The sprayer was operated at 200 psi and 3.4 mph and was outfitted with orange Albuz™ ceramic nozzles. The number of nozzles per row was increased from 6 to 8 to increase gallonage as the plants grew. Thus, 90 gpa was applied the first six sprays (six nozzles) and 120 gpa was applied for the remaining six sprays (eight nozzles). Admire treatments were applied in 4 oz water/plant on 13 Sept. The terminal leaflet was collected from a leaf from the upper third of each of 10 plants in the middle row of each plot on 9 Oct, 6 Nov and 4 Dec. Numbers of crawlers, sessile nymphs and pupae of the silverleaf whitefly (SLWF) were counted and the data were averaged over all dates for analysis. All of the plants in each plot were examined weekly for symptoms of virus. There are two viruses present which have nearly indistinguishable symptoms: tomato mottle virus (ToMoV), a geminivirus vectored by the SLWF, and potato virus Y (PVY), a potyvirus vectored by several species of aphids. All fruit of marketable size were harvested from the middle 10 plants of the middle row of each plot on 15 and 22 Dec. The fruit were separated by the presence or absence of southern armyworm damage and were counted and weighed. At the end of the experiment, a sample of three terminal leaflets was collected from each plant with ToMoV symptoms from the middle row of two checks. The samples were frozen for later determination of the presence of ToMoV using nucleic acid spot hybridization and the presence of PVY using ELISA.