Control of Tobacco Budworms with Foliar Insecticides, 1991

Abstract

Abstract Flue-cured tobacco was planted at the Central Crops Research Station, Clayton, NC, on 29 Apr in a field with a mix of Fuquay loamy sand and Norfolk loamy sand. Plots were 4 rows (45 inches apart) wide by 25 plants (ca. 55 ft) long, arranged in a randomized-complete block design with 10 treatments and 4 blocks. On 5 Jun, 10 uniformly sized and undamaged plants from each of the 2 left-most rows in each plot were tagged with surveyor's tape and artificially infested with a single 2-day-old laboratory-reared tobacco budworm larva. Larvae were transferred to the bud with a camel's hair brush. The 2 right-most rows provided an untreated buffer between plots. Sprays were applied with a Co2-pressurized sprayer through a single D2-33 full-cone nozzle per row at a rate of 25 gal/acre and 60 psi on 6 Jun. Four and lid after application, the number of surviving larvae on the tagged plants was counted. Budworm feeding damage (0-4) was determined after 14 d. On 2 Jul, all plants in the untreated buffer rows were cut off at 3-4 leaves above the ground. Suckers grew from the axils of the remaining leaves, and on 18 Jul all but one healthy, undamaged sucker were removed. A natural infestation of budworms and tobacco hornworms was present for this test. Sprays were applied on 9 Aug as described above. Four and 9 or 10 d after treatment, the number of surviving budworms and tobacco hornworms on 10 plants in each plot was counted. Before ANOVA, count data were transformed to count + 0.5. Treatments means were separated using the Waller-Duncan K-ratio t test (K = 100, a = 0.05). Means of untransformed data are presented.