Chemical Control of Heltiohis Spp. on Cotton, 1977

Stoneville 213 cotton variety was planted on April 29, 1977 at the North Farm of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS. Eight row plots, 100 ft long were arranged in a randomized complete block design replicated 4 times. Insecticides were applied to the center 4 rows of each plot at the rate of 4.17 gallons of mixture per acre, 4 mph, 40 psi and 3 nozzles per row. Applications for Heliothis spp. control were made 6 times on a weekly basis from July 20 to August 29, 1977. Azinphosmethyl was applied to all plots at 0.25 lb ai/acre an a weekly basis from July 5 to August 29 to control boll weevils, Anthonomusgrondis Boheman. Plots were examined weekly for Heliothis spp. damage by randomly selecting 25 squares from all parts of the plants along the center 2 rows. Yields were estimated by machine picking the center 2 rows on November 14, 1977. Heavy infestations of fall armyworms, Spodopterafrugiperda (J. E. Smith) were noted in these plots during early August. Approximately 50% of the larvae counted were fall armyworms on August 5, about 30% on August 12 and less than 5% on August 26, 1977.