Management of the Sweetpotato Whitefly and Geminivirus on Fresh Market Tomatoes in West-Central Florida, Spring 1992

Abstract

On 10 Feb, transplants were set 18 inches apart on raised beds of EauGallie fine sand covered with black polyethylene mulch. Plots consisted of 3 rows 20 ft long on 5 ft centers and were irrigated by a seepage subirrigation system. Insecticidal spray treatments were replicated 4 times in a randomized complete block design. Treatments were applied with a high clearance, self-propelled sprayer on 6, 16, 26, 31 Mar, 6, 13, 21 Apr, 4, 13, 19, 27 May, 3 and 11 June. The sprayer was operated at 200 psi and 3.4 mph and used hollow cone nozzles fitted with #3 disks and 25° cores. The number of nozzles per row was increased from 4 to 8 to increase gallonage as the plants grew. Thus, 60 gal/acre were applied the first four applications (4 nozzles), 90 gal/acre the next three applications (6 nozzles) and 120 gal/acre for the remaining six applications (8 nozzles). The Bay NTN treatments were applied as soil drenches on 2-3 Mar. On 5 Jun the number of Liriomyza spp. leafmines were counted in a 1 minute search of each plot. The terminal leaflet was collected from a leaf from the upper third of each of ten plants from the middle row of each plot on 8 Jun. The numbers of eggs, crawlers, sessile nymphs, pupae and pupae exuviae of the sweetpotato whitefly were counted. All plants were examined weekly for characteristic symptoms of tomato mottle virus, a geminivirus transmitted by the whitefly. One to two days following each insecticide application, a single, 1% inch square yellow sticky trap was placed in the middle row of each plot for 24 hrs and the number of whitefly adults trapped were counted. The traps were located adjacent to a plant 9-10 inches above the soil surface perpendicular to the ground surface and to the row. All fruit of marketable size was harvested on 18, 29 May and 9 Jun and the fruit was sized, counted and weighed.