Control of Aphids on Salad Crops, 1989

Abstract

Abstract The first crop of lettuce was direct-seeded at the Muck Crops Branch, Willard, OH, on 1 Jun. Plots were 3 rows wide (on 16 inch centers), with a different cultivar in each row, 18 ft long, and separated by 4 ft alleys. Each treatment, on each cultivar, was replicated 4 times in a randomized complete block design. All plots were treated on 7 Jul with Sevin 80 S, 0.4 lb (AI)/acre, to encourage aphid infestation. Treatments were applied on 22 Jul with a boom sprayer delivering 50 psi and 50 gal/acre. Weather immediately following treatment was hot, with daytime highs near 90°F. At harvest on 28 Jul aphids were counted on 3 plants in each plot by visual inspection of all leaves on each plant. Red lettuce, ‘Red sails’, was direct-seeded at the Muck Crops Branch on 25 Jul for the second trial. Plot arrangement and experimental design were identical to the earlier planting, but no initial application of Sevin was made and only ‘Red sails’ was used. Treatments were applied on 5 Sep, and weather immediately following treatment was moderate. On 8 and 11 Sep, aphids were rated on an approximately logarithmic scale (0 = 0 aphids, 1 = 1 ° 4 aphids, 2 = 5 ° 10 aphids, 3 = 11 - 33 aphids, 4 = 34 ° 100 aphids, 5 = 101 ° 300 aphids, 6 = > 300) on 5 plants in each plot by visual inspection of all leaves on the plant. Analyses of variance were performed on the untransformed counts for the first treatment date, and on the ratings for the second.