Evaluation of Insect-Resistant Cotton Against Bollworm, 2016

Selected varieties of Phytogen cotton expressing different proteins from Bacillus thuringiensis (Bt) were evaluated for control of bollworm at Lee Farm in Hayward, MO, which is the field location for the Fisher Delta Research Center. The varieties/technologies included Phytogen 499WRF (expressing Cry1F and Cry1Ac), Phytogen 495W3RF (expressing Cry1F, Cry1Ac, and Vip3A), and Phytogen 315RF (non-Bt). Cotton was planted in 9 Jun at a rate of 41,414 seeds per acre. The test was arranged in an RCB design with four replicates, and plot size was 13 × 40 ft. Plots were visually examined, sampling the outside two rows of each four-row plot. On the first date, 13 Jul, 20 terminals were examined for the presence and number of bollworms. On the second date, 25 Jul, at first squaring, 40 squares were sampled. On the third date, 18 Aug, at first bloom, 40 flowers were sampled. On the fourth date, 28 Sep, when the first bolls appeared, 40 bolls were sampled. Data were subjected to ANOVA and means were separated using a protected LSD.

Phytogen 499WRF and Phytogen 495W3RF had significantly fewer bollworm larvae on each of the four sampling dates than the non-Bt variety Phytogen 315RF (Table 1). Also, Phytogen 495W3RF had significantly fewer larvae than Phytogen 499WRF in 25 Jul and 28 Sep, respectively. This research was partially supported by industry gifts of pesticide and seed.

Author notes