Abstract

Field studies were carried out at Hoytville and Wooster, Ohio, USA from 2006 to 2008 to determine the influence of planting date and transgenic Bt maize on incidence and severity of stalk rots of maize. Transgenic and non-transgenic Bt maize hybrids with different maturity ratings were planted on late April/early May, mid-May and early June each year. The incidence and severity of the maize stalk rot complex were compared among planting dates and between Bt and non-Bt genotypes of different relative maturities. Significant linear correlations between European corn borer (Ostrinia nubilalis Hub.) injury to stalk and stalk rots were observed in 2006, and 2007, but not in 2008. We observed significant reduction in stalk discoloration and incidence of maize stalk rot on Bt hybrids compared with non-Bt genotypes. Short season hybrids had significantly lower stalk rots than full season hybrids. The benefit of using Bt hybrids to reduce stalk rots was more evident as planting was delayed than early planting.

Key words: Transgenic hybrids, relative maturity, planting date, stalk rots.