Flumioxazin Preplant Burndown Weed Management in Strip-Tillage Cotton (Gossypium hirsutum) Planted into Wheat (Triticum aestivum)1

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.