Cotton (Gossypium hirsutum) Response to Imazaquin and Imazethapyr Soil Residues

Abstract

The effects of imazaquin and imazethapyr on cotton planted the year following application to soybean were studied on one silt loam and two clay soils in Arkansas from 1989 to 1991. Imazaquin was applied to soybean at 0.07 kg ai ha−1PPI and POST, 0.14 kg ha−1PPI, PRE, and POST, and sequentially PPI or PRE followed by POST at 0.14 kg ha−1per application. Imazethapyr was applied at 0.035 kg ha−1PPI and POST, 0.07 kg ha−1PPI, PRE, and POST, and sequentially PPI or PRE followed by POST at 0.07 kg ha−1per application. Soil residues of 0.07 kg ha−1imazaquin and imazethapyr did not injure cotton at any location. Residues of 0.14 kg ha−1imazaquin applied sequentially reduced cotton shoot dry weight for 6 wk after emergence on clay but not on silt loam soil. The PPI followed by POST sequential imazaquin treatment (0.28 kg ha−1total imazaquin) delayed initiation of fruiting and reduced yield and lint quality.