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

Abstract

Abstract On 10 Mar, transplants were set 18 inches apart on raised beds of EauGallie fine sand covered with black polyethylene mulch. Plots comsisted of 3 rows 20 ft long on 5 ft centers. Plants were grown staked 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 17, 25, 30 Mar, 8, 15, 22 Apr, 7, 14, 20, 29 May, 4 and 12 Jun. 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 six sprays (4 nozzles), 90 gal/ acre the next three sprays (6 nozzles) and 120 gal/acre for the remaining three sprays (8 nozzles). The terminal leaflet was collected from a leaf from the upper third of each often plants from the middle row of each plot on 3 and 18 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. All fruit of marketable size were harvested on 2, 11 and 18 Jun and the fruit were counted and weighed. On the last two harvests, a subsample of 50 ripe fruit were rated 1 to 3 for increasing severity of external symptoms of irregular ripening. This disorder is associated with high populations of the sweetpotato whitefly and is characterized by incomplete or inhibited ripening of longitudinal sections of fruit.