The Influence of Fluometuron and MSMA on Cotton Yield and Fruiting Characteristics

Abstract

Field experiments conducted from 1987 through 1991 at the Delta Branch Experiment Station, Stoneville, MS, determined the effect of postemergence topical applications of fluometuron and MSMA on cotton yield and fruiting. Herbicide treatments applied to cotton in the cotyledon to 1-leaf growth stage were 1.12 kg ai ha-1fluometuron plus 0.25% by vol nonionic surfactant, 2.2 kg ai ha-1MSMA, and a combination of 1.12 kg ha-1fluometuron and 2.24 kg ha-1MSMA. The commercial formulation of MSMA contained nonionic surfactant. Visual injury of cotton 14 d after treatment ranged from 14 to 28% for fluometuron, 9 to 26% for MSMA, and 22 to 34% for the combination. Seed cotton yield at the first harvest was reduced by all herbicide treatments except in 1987 and for DES 119 cotton in 1990. In 1990, yield of DES 119 cotton treated with MSMA and the combination was less than the untreated control for the second harvest interval. Cotton yield from herbicide treatments at later harvests was equal to or greater than the untreated control. Only in 1988 did all treatments reduce total seed cotton yield below the untreated control. Fiber quality was not adversely affected by the herbicides. Compared to the control, plant mapping indicated that the number of sympodial branches per plant was reduced by MSMA and by the combination for DPL 50 cotton in 1990. Averaged over 4 experiment years, herbicide treatments did not reduce total bolls per plant; percentage of bolls in first, second, or outer positions; highest sympodium with two bolls; or number of sympodium with bolls in the first or second position. However, MSMA and the combination increased node number of the first sympodia by one and 1.5 positions, respectively, when compared to the control, indicating delayed maturity.