Evaluation of New Transgenic Corn Hybrids Producing Multiple Bacillus thuringiensis Toxins in South Carolina

Transgenic corn, Zea mays L., hybrids expressing insecticidal Cry proteins from Bacillus thuringiensis (Bt) were evaluated for control of insect pests in Florence and Blackville, SC, in 2009 and 2010. Two planting dates were used in trials in 2010. Early- and midseason pests and associated injury were consistently absent or at low numbers. Data analyses were limited primarily to Helicoverpa zea (Boddie) injury and infestations in corn ears. In Florence in 2009, event MON89034 reduced injury by 97% based on number of injured kernels per ear compared with the non-Bt isoline. Events TC1507 reduced injury by 53% across both years and locations of our study. The combined events MON89034 and TC1507 in a SmartStax hybrid significantly (P < 0.05) reduced injury by 98% compared with the non-Bt isoline across both years and locations of our study. The excellent control of H. zea in SmartStax was, therefore, the result of the MON89034 event, rather than the TC1507 event. Planting date did not significantly (P > 0.05) affect injury or yield at both locations in 2010. Yield was not affected by Bt traits. The increased effectiveness of recent hybrids with the MON89034 event in controlling H. zea in corn ears may lead to increased planting of Bt corn in the southeastern United States, as prior events were not as effective in controlling this key pest.