Abstract: Experiments were conducted at two locations in North Carolina from 1999 to 2000 to evaluate flumioxazin preplant (PP) for weed management in strip-tillage cotton planted in winter-wheat cover. Flumioxazin PP was evaluated at two rates alone and in mixture with two commonly used PP herbicides and one experimental PP herbicide. Flumioxazin PP at 71 or 105 g ai/ha tank mixed with the isopropylamine salt of glyphosate at 1.12 kg ai/ha, paraquat at 1.05 kg ai/ha, or the trimethylsulfonium salt of glyphosate at 1.12 kg ai/ha controlled common chickweed, common lambsquarters, common ragweed, Palmer amaranth, and smooth pigweed ≥ 96% 29 to 43 d after treatment (DAT). Both glyphosate formulations and paraquat alone provided ≥ 91% control of common chickweed and henbit 29 to 43 DAT, but control of common lambsquarters, common ragweed, large crabgrass, Palmer amaranth, and smooth pigweed was ≤50%. Treatments including flumioxazin injured cotton (≤ 5%) at one location. In all comparisons within a location, cotton treated with flumioxazin PP at 71 or 105 g/ha in mixture with either glyphosate formulation or with paraquat provided equivalent or higher yields than did cotton not treated with flumioxazin PP.
Nomenclature: Flumioxazin; glyphosate; paraquat; common chickweed, Stellaria media L. Vill. #3 STEME; common lambsquarters, Chenopodium album L. CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; henbit, Lamium amplexicaule L. # LAMAM; large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA; Palmer amaranth, Amaranthus palmeri L. # AMAPA; smooth pigweed, Amaranthus hybridus L. # AMACH; cotton, Gossypium hirsutum L. ‘Paymaster 1218 RRBG’, ‘Paymaster 1220 RRBG’; wheat, Triticum aestivum L.
Additional index words: Burndown treatment, cover crops.
Abbreviations: COC, crop-oil concentrate; DAT, days after treatment; glyphosate-IP, isopropylamine salt of glyphosate; glyphosate-TM, trimethylsulfonium salt of glyphosate; PDS, postemergence-directed spray; POST, postemergence; PP, preplant; PRE, preemergence; WAP, weeks after planting.