Pyrethroid/Organophosphate Combinations for Management of the Sweetpotato Whitefly and Geminivirus on Fresh Market Tomatoes in West-Central Florida, Spring, 1991

On 8 Mar, transplants were set 18 in apart on raised beds of EauGallie fine sand covered with black polyethylene mulch. Plots consisted of three 50-ft-long rows on 5 ft centers separated by 50 ft. Treatments were replicated 2 times in a randomized complete block design. Treatments were applied with a high clearance, self-propelled sprayer on 15, 19, 26 Mar, 2, 9, 16, 22 Apr, 1, 8, 13, and 29 May. The sprayer was operated at 200 psi and 3.4 mph and used hollow cone nozzles fitted with D-3 disks and #25 cores. The numbers of nozzles per row were increased from 4 to 8 to increase gallonage as the plants grew. Thus, 50 gal/acre were applied the first seven sprays (4 nozzles), 75 gal/acre the eighth and ninth sprays (6 nozzles), and 100 gal/acre for the remaining sprays (8 nozzles). A single four inch square yellow water pan trap was placed in the center of the middle row of each plot for 24 hrs weekly. Three leaves from the upper, middle, and lower canopy were examined weekly from each of 10 plants from the middle row of each plot and the number of sweetpotato whitefly adults were counted. The terminal leaflet was collected from the 7th or 8th leaf (counting from the top) of each of 20 stems from the middle row of each plot on 23 Apr, 9, 23 May, and 7 Jun. The numbers of eggs, crawlers, sessile nymphs, pupae, and pupa exuviae of the sweetpotato whitefly were counted. All plants were examined weekly for characteristic symptoms of an unknown geminivirus transmitted by the whitefly. All fruit of marketable size were harvested on 24 May and 3 Jun and the fruit were sized, counted, and weighed.