Duster-low-volume sprayer comparison in applying insecticides to snap beans

The objective of this study was to compare the effectiveness of two makes of low-volume sprayer and one make of duster in applying insecticides for controlling cab-bage loopers on snap beans. With the low-volume machines, five gallons of mix per acre was used; with the conventional duster 25 pounds of mix per acre was used. A fluorescent particle technique was used to determine the insecticide particle deposition on the foliage. Machine performance was evaluated by count of deposited particles. The low-volume sprayers were more efficient in apply-ing insecticide material to plant leaves than the duster. Between low-volume sprayers there was no significant differ-ence. It was found that the insecticide deposition achieved with the low-volume sprayers was almost 250 percent greater than that of the duster. The low-volume Span Spray unit pro-duced the highest deposition mean (122.12 FP/mm²) and the lowest insecticide drift. Second was the John Blue sprayer 9 2 (120.52 FP/mm²) and last in rank was the duster (49.82 FP/mm²). Also, application dates (replications), blocks, rows, and leaf sides effects were significant. The third replication had higher particle counts than the second and the second had higher counts than the first. The difference indicates an accumulative effect of the insecticide on the crop with succeeding replications. Row 7 particle counts were higher than those of Row 8 for all the machines. The top of the leaf was found to receive more insecticide material than the bottom for all the machines and at two different heights on the plant. Loopers apparently were controlled by both Sevin and Thuricide HP, although looper infestation, even on the check plots, was too low for conclusive control prediction. There was poor control of Mexican bean beetles, with Sevin provid-ing better control of these beetles than Thuricide HP. There was a better control of flea beetles by both Sevin and Thuri-cide HP treatments. Again, Sevin proved superior.