Control in Sweet Potatoes, 1987:

The experiment was conducted in Gadsden County, Fla., on Ruston fine loamy sand. Preplanting incorporated insecticide treatments were applied on 7 May using a tractor-mounted sprayer equipped with 8003 nozzles. Pressure was 25 psi and the amount of spray,was 25 gal/acre. Sweet potato slips were planted 12 inches apart on 36-inch rows on 14 May. Granular insecticide treatments were applied during sweet potato root swell on 22 Jul in a 12- to 15-inch band over the row with a push-type Gandy applicator. Experimental design was a randomized complete block with 4 replicates. Plot size was 6 rows by 40 ft. Rainfall was below normal in May and June, with 1.40 and 1.71 inches recorded, respectively. Rainfall was normal or above normal for July, August, September, and October, with 7.19, 12.85, 2.15, and 2.80 inches recorded, respectively. Plots were located under a center pivot, overhead-sprinkler system and were irrigated with 0.50-1.0 inches of irrigation on several dates. Plots were irrigated with 0.50 inches immediately after treatments on 22 Jul were applied. The entire length of 1 of the 2 center rows was harvested in each plot in late October, and marketable yield (U.S. No. 1) determined. The amount of WW and SFB damage was estimated for each plot by counting injury on 15 randomly selected potatoes from the marketable yield. For these ratings, the number of potatoes with SFB larval tunneling and WW feeding holes and the total number of SFB tunnels and WW feeding holes were quantified. Treatment effects of yield and insect injury were compared at the 5% level using ANOVA and DMRT.