Tobacco Budworm Control on Flue-Cured Tobacco with Foliar Insecticides, 1996

Abstract

Abstract Flue-cured tobacco was planted on the James T. Smith farm in Wayne Co., NC on 23 Apr. Plots of 0.02 acre (4 rows X 57 ft) were separated laterally by a vacant 5th row and on each end by turn alleys of 16 ft. Treatments were established in a RCB design with 4 replications. Just prior to treatment, a moderate natural infestation of budworms was augmented by artificial infestation of 10 plants in each of the 1st and 3rd rows of each plot. A single 2-d old larva (from the colony maintained by the Dept. of Entomology, N.C. State University) was transferred from artificial diet to each plant. Larvae were placed into the bud to simulate an established infestation. Treatments were applied on 3 Jun using a tractor-mounted sprayer (with the exception of Dipel 10 G) pressurized by a roller pump powered by the tractor PTO. Spray was delivered through 3 solid-cone nozzles (TG-1, TG-2, TG-1) per row at 60 psi and 37.5 gpa. Treatments were applied between 2:50 pm and 5:00 pm EDT. Diatect was treated as a wettable powder and sprayed. Dipel 10G was applied by hand directly to the bud of each plant. Air temperature was approximately 80° F and winds were light to moderate (3-7 mph). All plants (excluding the first and last) in rows 1 and 3 were checked for budworm infestation on the day of treatment and 4 and 11 DAT. These plants were rated for budworm damage 15 DAT. Individual plants were examined and an estimate of leaf area lost to budworm feeding made. Damage was scored as follows: 0 = no damage; 1 = less than 1.0 leaf equivalent lost; 2 = 1.0 - 2.0 leaf equivalents; 3 = more than 2.0 leaf equivalents lost; 4 = plant topped by budworm feeding. Average damage ratings were calculated by plot. After harvest and curing, tobacco from each plot was weighed and graded by a government grader. Grades were converted to a quality index (1-100, 100 high). All variables were subjected to analysis of variance and treatment means compared (where appropriate) using an LSD test. Before analysis, the proportion of plants infested was transformed to the arcsine of square root of proportion. Data shown in the table are not transformed and proportion of plants infested is presented as percentage of plants infested.