Control of the Green Peach Aphid and Tobacco Hornworm on Flue-Cured Tobacco with Soil-Applied Insecticides, 1982

Abstract

Abstract A test was conducted on commercially grown tobacco in Wayne Co., N.C. The soil type was Goldsboro sandy loam. Plots were 0.020 acre (16 by 54.4 ft), four rows wide, separated on each side by a vacant row and on the ends by a 20-ft alley. Treatments were arranged in a randomized complete-design with four replications. Broadcast sprays were applied 14 Apr. using a tractor-mougted boom sprayer delivering ca. 25 gal finished spray per acre through 8004 flat fan nozzles at 35 lb/in2. Incorporation was accomplished by discing twice in opposite directions. The broad band treatment was applied in a 14 in. band over the top of a partially formed bed using a tractor-mounted electric granular applicator (30 Apr.). This band was covered by 2 to 3 in. of soil with a hilling disc. Narrow band treatments were applied 30 Apr. in a 2 to 3 in. band ca. 3 in. below the surface of a partially formed bed and covered with an additional 2 to 3 in. of soil. Transplant water treatments were made 4 May using the farmer’s tractor-drawn transplanter delivering 75 gal/acre. Sidedress treatments were applied in a 2 to 3 in. band ca. 2 in. below the surface to one side of each row (25 May). Twenty plants in the middle two rows were rated for aphid infestation as follows: 0, fewer than 10 aphids on any one leaf; 1, 11 to 50 aphids on any one leaf; 2, 50+ aphids on any leaf; 3 plant heavily infested, honeydew and sooty mold obvious. Plants rated 2 or 3 were considered infested. Aphids were counted on the first leaf from the top at least 6 in. long or the second leaf from the top after topping (10 plants). Hornworms were counted on 20 plants in the middle two rows. After curing, each plot per harvest was weighed and graded. Government grades were converted to a quality index and a weighted average computed. All variables were subjected to an analysis of variance and means separated using the Waller-Duncan K ratio t test (K-ratio = 100). Before analysis, aphid and hornworm numbers were transformed to the square root of N +0.5. Infestation ratings were converted to a proportion of the maximum possible and these and % infested plants were subjected to an arc sine transformation.