An experiment was conducted in Leland, MS in 1998, 1999, and 2000 to evaluate various heliothine management systems in ultra-narrow row (UNR) cotton. The study was conducted as a split-split block design. Whole plots were 7.5" and 38" rows (wide-row). Sub-plots were B.t and non-B.t. cotton. Sub-sub-plots were treatment thresholds including: 2%, 4%, 8%, and 12% infested plants. Data collected in 1998 were used to establish thresholds for the for the 1999 and 2000 study. Plots were monitored bi-weekly and sprayed for Heliothis virescens, Tobacco budworm and Helicoverpa zea, Cotton bollworm according to established thresholds. Ultra-narrow row and 38" row B.t. plots did not reach established thresholds in 1999. Wide-row non-B.t. 2% plots were sprayed for budworm/bollworm four times and UNR plots were sprayed two times in 1999. In 2000, 2% B.t. wide row plots received two budworm/bollworm sprays, 4% B.t. wide-row plots were sprayed once. B.t. UNR plots did not trigger a budworm/bollworm spray in 2000. In 2000, wide-row 2% non-B.t. plots received seven applications for budworm/bollworm, wide row 4% non-B.t. plots were sprayed six times, wide row 8% non-B.t. plots were sprayed four times, wide-row 12% non-B.t. plot were sprayed three times, UNR 2% plots were sprayed three times, UNR 4% non-B.t plots were sprayed one time and UNR 8% and 12% plots did trigger an application.

Data for 1999 and 2000 were pooled. B.t. and non-B.t. UNR plots had significantly fewer budworm/bollworm than wide-row B.t. and non-B.t. plots respectively. No significant differences were observed in budworm/bollworm numbers at any treatment threshold in the B.t. plots. In the non-B.t wide row plots the 2% plots had significantly fewer budworm/bollworm larvae than the 8% and 12% plots. Significantly more eggs were found in the wide row planting compared to the UNR plantings (~3X). There were no significant differences in yield in 1999 or 2000 among any treatments. Numerically, UNR plots tended to yield slightly higher in both years of the study although not significantly. Ultra-narrow row plots set one to three bolls per plant and cutout 7-10 days earlier than the 38" row plantings. The data suggests that UNR is possibly not as attractive to heliothines for oviposition as wide row plantings.