Evaluating the Performance of Transgenic Corn Producing 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 from 2007 to 2009 in Florence and Blackville, South Carolina. Two planting dates were used in trials in 2009. Early- and mid-season pests and associated injury were consistently absent or at low numbers. Data analyses were limited to Helicoverpa sea (Boddie) injury and infestations in corn ears. Based on the number of kernels injured per ear, event MON810 significantly (P < 0.05) reduced injury compared with the non-Bt isoline in both trials in 2008 (average of 67% control), but reduced injury only in 2009 at the Florence location (64% control). Event TC1507 significantly reduced injury relative to its non-Bt isoline in trials in 2008 by an average of 51%. Based on one year of data at two locations in 2009, event MON89034 significantly reduced injury relative to the non-Bt isoline (average of 83% control), and was more effective than MON810 in the same trials. In 2009, the plots planted at the later date had significantly (P < 0.05) less injury on ears and kernels than the first planting date in Blackville; no differences were detected in Florence. Yield was not affected by Bt traits in any of the trials. 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.