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

Abstract

Abstract Flue-cured tobacco was planted on the Casey farm in Johnston Co., NC on 3 May. 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. Treatments were applied 21 Jun using a tractor mounted sprayer pressurized by a PTO-powered roller pump. Spray was delivered through 3 hollow-cone nozzles (TX-12) per row at 60 psi and 36.5 gpa. Treatments were applied between 9:30 am and 11:30 am EDT. Air temperature was 80-84° F and winds were light (3-5 mph). All plants (excluding the first and last) in rows 1 and 3 were checked for aphid infestation on the day of treatment and 5 and 12 DAT. Individual plants were rated for degree of aphid infestation as follows: 0 = no aphids on plant; 1 = 1-10 aphids on most infested leaf (MIL); 2 = 11-50 aphids MIL; 3 = 51-200 aphids MIL; 4 = 201-500 aphids MIL; 5 = 500+ aphids MIL. Average infestation ratings were calculated by plot. The proportion of plants infested (rated 3 or above) was also calculated. 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 were compared (where appropriate) using the LSD t-test. Before analysis, the proportion of plants infested was transformed to the arcsine of the square root of the proportion. Data shown in the tables are not transformed and proportion of plants infested is presented as the percentage of plants infested.