Field studies were conducted in 1999, 2000, and 2001 to evaluate broadleaf weed control in glyphosate-resistant cotton by glyphosate plus CGA 362622 applied postemergence. Treatments included 560 and 1,120 g ai/ha glyphosate-isopropylamine alone or in mixtures with CGA 362622 at 3.8 and 7.5 g ai/ha, and CGA 362622 at 7.5 g/ha alone. Cotton injury 7 d after treatment (DAT) was 3 to 11% from glyphosate alone and 16 to 24% from glyphosate plus CGA 362622. Injury 28 DAT with CGA 362622 or herbicide mixtures did not exceed 6%. Broadleaf weed control by herbicide mixtures was generally more consistent than control from either herbicide applied alone. Glyphosate plus CGA 362622 controlled common cocklebur and smooth pigweed better than glyphosate alone. In most instances, the mixtures also controlled common ragweed, common lambsquarters, ivyleaf morningglory, pitted morningglory, and tall morningglory better than glyphosate applied alone. Common cocklebur and smooth pigweed were controlled at least 85% by all treatments. CGA 362622 did not control spurred anoda or jimsonweed. Cotton yields generally reflected weed control. According to these results, glyphosate plus CGA 362622 mixtures can consistently control many broadleaf weeds in cotton.
Nomenclature: CGA 362622 (proposed common name trifloxysulfuron sodium), N-[(4,6-dimethoxy- 2-pyrimidinyl)carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridin-2-sulfonamide sodium salt; glyphosate; common cocklebur, Xanthium strumarium L. #3 XANST; common lambsquarters, Chenopodium album L. # CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; ivyleaf morningglory, Ipomoea hederacea (L.) Jacq. # IPOHE; jimsonweed, Datura stramonium L. # DATST; pitted morningglory, Ipomoea lacunosa L. # IPOLA; smooth pigweed, Amaranthus hybridus L. # AMACH; spurred anoda, Anoda cristata (L.) Schlecht. # ANVCR; tall morningglory, Ipomoea purpurea (L.) Roth # IPOPU; cotton, Gossypium hirsutum L. ‘PM 1220 RR’, ‘PM 1218 BG/RR’, ‘SG 521 RR’.
Additional index words: Herbicide mixtures, morningglory species.
Abbreviations: DAT, days after treatment; POSD, postemergence directed; POST, postemergence.