Abstract On 8 Sep, transplants were set 18 inches apart on raised beds of Eau Gallie fine sand covered with white polyethylene mulch. Plots consisted of 3-20 ft long rows on 5-ft centers and were irrigated by a seepage subirrigation system. Treatments were replicated 4 times in a randomized complete block design and were applied with a tractor-mounted sprayer on 2, 10, 16, 23, 30 Oct, 6, 13, 20, 27 Nov and 4 Dec. The gallonage was increased as the plants grew by increasing the number of nozzles/row and application pressure and by changing disks and cores. Thus, the sprayer delivered 50 gal/acre the first 3 sprays (4 nozzles/row, 130 psi, D-4 disks, #25 cores), 85 gal/acre the next 3 sprays (6 nozzles, 200 psi, D-3 disks, #25 cores), and 100 gal/acre for the remaining sprays (8 nozzles, 200 psi, D-3 disks, #23 cores). The terminal leaflet was collected from the 7th or 8th leaf (counting from the top) of each of ten stems from the middle row of each plot on 8 Nov and 7 Dec. The numbers of sessile nymphs and pupae of the sweetpotato whitefly were counted. All fruit of marketable size were harvested on 8 Dec and the fruit were counted and weighed. Samples of 50 fruit from each plot were held at room temperature in paper bags and the number of fruit exhibiting external symptoms of irregular ripening (IRR) were determined as the fruit ripened. IRR is associated with high populations of the sweetpotato whitefly and is characterized by inhibited or incomplete ripening of longitudinal sections of fruit.
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