Control of Wireworms and Flea Beetles in Flue-Cored Tobacco with Soil-Applied Insecticides, 1983

Abstract

Abstract A test was conducted on commercially grown tobacco in Stokes Co., N.C. Plots were 0.025 acre (24 by 45 ft), six rows wide, separated laterally by a vacant row and on each end by a 12-ft turn alley. Treatments were arranged in a randomized complete-block design with three replications. Broadcast sprays were applied 1 May using a tractor-mounted boom sprayer delivering 23.25 gal/acre of finished spray through 8004 flat fan nozzles at 25 lb/in2. Granular broadcast applications were made on the same date using two electrically driven tractor-mounted Gandy granular applicators. All broadcast applications were incorporated by discing twice in opposite directions with a small finishing disc. A transplant water treatment was made 18 May using the farmers one-row tractor-drawn transplanter (180 gal/acre). Forty additional plants were set in the middle four rows using hand setters. On 2 Jun., these plants, or adjacent mechanically set plants in the case of the transplant water treatment, were removed and evaluated for wireworm damage on the following scale: 0, no damage; 1, surface feeding not reaching pith; 2, feeding reaching pith but vertical tunneling not over 0.5 in, 3; vertical tunneling in excess of 0.5 in; 4, extensive tunneling, plant obviously dead or dying. Flea beetles and flea beetle feeding holes were counted on 10 plants per plot on 2 and 15 Jun. (Feeding holes were counted on the entire plant in 2 Jun. and on the uppermost three leaves over 4 in. long on 15 Jun.) On 15 Jun., possible phytotoxic effects were observed in some plots. Each plot was rated for overall vigor (1 to 5, 5 best) and two types of possible phytotoxicity (1 to 3, 3 most extensive). Leaves over 4 in. long were counted on 20 plants per plot. After harvest and curing, tobacco from each plot per priming was weighed and graded. Government grades were converted to a quality index and 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). For analysis, the number of flea beetles and number of flea beetle holes were transformed to the square root of n + 0.5.