Planting date effects on hellothine larval numbers, fruit damage, and yield of transgenic B.t. cotton in North Carolina

The susceptibility of Bollgard (R) cotton and non-B.t. cotton to bollworm, Helicoverpa zea (Boddie), was examined under contrasting crop management st rategies in northeastern North Carolina in 1995, 1996, and 1998. Specifical ly, planting date effects were observed in Edgecombe Co. in 1995 and 1996, in Martin Co. in 1996, and in Washington Co. in 1998. The bollworm was the only lepidopterous pest which occurred at damaging levels in these tests. A lthough no significant differences were detected in mean percent egg deposi tion, mean percent larval infestation, and mean percent damaged fruit betwe en early-planted and late-planted plots in 1995 and 1996, yields were highe r in early-planted cotton than in late-planted cotton. In 1998 mean percent damaged fruit was higher in early-planted cotton than in late-planted cott on, but early-planted cotton had significantly higher yields than late-plan ted cotton. Early planting may be an effective management strategy for Boll gard (R) cotton in northeastern North Carolina.