Control of Black Cutworms and Flea Beetles with Karate, 1989

Abstract

Abstract Tobacco was transplanted at the Central Crops Research Station, Clayton, NC, on 15 May in a Norfolk loamy sand. Plots were 2 rows (45 inches apart) by 22 plants (ca. 45 ft) arranged in a randomized-complete block design with 5 treatments and 4 blocks. Plots were separated by one untreated buffer row. On 31 May, 6 consecutive plants in row 1 were individually encircled with a 16 inch diam plastic-lawn edging barrier. Near each plant, a small indentation was made in the soil by hand and 3 third-instar black cutworm larvae were released. After the larvae were released, they were covered with a small amount of wheat straw to prevent bird predation and dehydration. Soil moisture was excellent. On the evening of 1 Jun, treatments were applied at 60 psi and a rate of 25 gal/acre through a single D2-33 Spraying Systems nozzle/ row using a CO2-powered sprayer. At the time of application winds were calm, temp, was 90°F and relative humidity was high. On 5 Jun, the soil inside the barrier was sifted and examined for dead and surviving larvae. Individual plants were rated for cutworm damage as follows: 0 = no damage, 1 = slight damage (>5 small holes per plant), 2 = mild damage (>5 small holes or <3 large holes per plant), 3 = moderate damage (>3 large holes, portions of leaves eaten or 1 cut leaf), 4 = heavy damage (numerous large holes, several leaves or but cut), 5 = dead (cut) plant. On 9 Jun, the number of tobacco flea beetle adults and tobacco flea beetle feeding holes were counted on 10 consecutive plants in row 2 from each plot. Data were analyzed using ANOVA and Waller-Duncan K-ratio t tests (K = 100) were used to separate treatment means. Counts of the number of surviving black cutworm larvae and the flea beetle adult and feeding hole counts were transformed to count + 0.5 before ANOVA.