Three experiments were conducted in Lewiston, NC, from 1999 through 2002 to evaluate the influence of various application timings of flumioxazin preplant (PP) and postemergence-directed spray (PDS) on cotton injury. In experiment 1, flumioxazin was evaluated in a reduced-tillage system at 71, 105, or 140 g ai/ha in mixture with glyphosate, applied at 28, 14, or 7 d before planting (DBP), followed by irrigation at cotton emergence. Flumioxazin applied PP at any rate and irrigated at emergence injured cotton less than 7% at 2 wk after emergence (WAE) and less than 6% 5 WAE. In experiment 2, flumioxazin was evaluated in a conventional-tillage system at 71 or 105 g/ha as a PDS treatment applied to dry soil, wet soil, and dry soil irrigated immediately after application when cotton was 20 to 30 cm height. Cotton treated with flumioxazin PDS at either rate applied to dry soil, wet soil, or dry soil followed immediately by irrigation was not injured. In the third experiment, flumioxazin at 71 g/ha alone or in mixture with glyphosate at 1.12 g/ha was applied at 30, 21, 14, and 0 DBP in a conventional-tillage system. Flumioxazin applied alone or in mixture with glyphosate applied at any time did not injure cotton. In all experiments, cotton lint yields were not influenced by herbicide treatment.

Nomenclature: Flumioxazin; glyphosate; cotton, Gossypium hirsutum L., ‘Deltapine 5415 RRBG’, ‘Paymaster 1218 RRBG’, ‘Suregrow 125’.

Additional index words: Burndown treatment, LAYBY treatment.

Abbreviations: COC, crop oil concentrate; DBP, days before planting; MSMA, monosodium salt of methylarsonic acid; NIS, nonionic surfactant; PDS, postemergence-directed spray; POST, postemergence; PP, preplant; PRE, preemergence; WAE, weeks after emergence.