Field studies were conducted in 1998 and 1999 to evaluate the response of seven cotton cultivars to CGA-362622 applied postemergence at 7.5 and 15 g ai/ha to three- to five-leaf cotton. The cultivars evaluated included Deltapine 51, Deltapine NuCotn 33B, Paymaster 1220 RR, Paymaster 1220 BG/RR, Stoneville bromoxynil-resistant 47, Stoneville 474, and Sure-Grow 125. At 1 to 2 wk after treatment (WAT), CGA-362622 at 7.5 and 15 g/ha injured all cotton cultivars 7 to 9% and 13 to 15%, respectively. Cotton injury symptoms included chlorosis and minor stunting. At 3 to 4 WAT, injury from CGA-362622 at 7.5 and 15 g/ha was 2 to 6% and 7 to 9%, respectively. Except for Paymaster 1220 RR, Deltapine NuCotn 33B, and Stoneville 474, all cotton cultivars were injured more by the higher rate than by the lower rate of CGA-362622. Injury was not visibly apparent 6 to 8 WAT. CGA-362622 at either rate had no effect on cotton lint yield.

An experiment was conducted at five locations in North Carolina during 2000 and 2001 to evaluate weed control, crop injury, and cotton yield. Weed management systems included different combinations of pyrithiobac preemergence (PRE), fluometuron PRE, CGA-362622 postemergence (POST), pyrithiobac POST, and monosodium salt of methylarsonic acid (MSMA) plus prometryn applied late POST-directed (LAYBY). At Goldsboro in 2000, cotton was injured 74 to 78% by CGA-362622 POST when evaluated 4 to 7 d after treatment (DAT). Injury at Clayton, Goldsboro, and Lewiston in 2001 and Rocky Mount in 2000 was less than 16% 4 to 7 DAT with the same treatment and was not apparent by 62 DAT. CGA-362622 controlled common lambsquarters, common ragweed, Palmer amaranth, sicklepod, smooth pigweed, and Ipomoea species including entireleaf, ivyleaf, and pitted morningglory, and the addition of pyrithiobac to the herbicide system, either PRE or POST, increased control of Amaranthus species, jimsonweed, and prickly sida. CGA-362622 did not control jimsonweed or prickly sida. Fluometuron PRE, pyrithiobac PRE, and MSMA plus prometryn LAYBY were beneficial for increasing weed control and cotton lint yields. Prometryn plus MSMA LAYBY increased control of common ragweed, entireleaf morningglory, jimsonweed, pitted morningglory, and smooth pigweed and provided higher cotton yields than similar systems without a LAYBY. The greatest weed control and greatest cotton lint yields required complete weed management systems that included a combination of PRE, POST, and LAYBY treatments.

Studies were conducted at Clayton, Lewiston, and Rocky Mount, NC, to evaluate weed and cotton response to herbicide systems in bromoxynil-resistant Stoneville BXN 47 cotton. Herbicide systems that included clomazone preemergence (PRE) controlled broadleaf signalgrass, common lambsquarters, common ragweed, goosegrass, large crabgrass, and prickly sida greater than 88%. Inconsistent Palmer amaranth control was observed with the addition of fomesafen PRE to clomazone PRE and pendimethalin preplant-incorporated (PPI) herbicide systems. Addition of bromoxynil early postemergence (EPOST) to clomazone and pendimethalin systems increased ivyleaf morningglory control to greater than 84% and provided higher yields than did the same systems without bromoxynil. Bromoxynil EPOST followed by (fb) cyanazine + MSMA late postemergence directed (LAYBY) improved weed control in clomazone and pendimethalin systems. Clomazone PRE and pendimethalin PPI with or without fomesafen PRE fb bromoxynil EPOST fb LAYBY herbicides controlled weeds and yielded equivalent to the standard herbicide system of pendimethalin PPI fb fluometuron PRE fb bromoxynil EPOST fb LAYBY.