Suppression of Red Rice (Oryza sativa) Seed Production with Fluazifop and Quizalofop

Abstract

Field research was conducted in 1985 and 1986 to compare the efficacy of fluazifop and quizalofop on production of panicles and seeds of red rice. Single and first sequential treatments were applied to red rice in the early-tillering, midtillering, and panicle initiation stages of growth. Sequential treatments were applied 14 days after each earlier application to red rice in the midtillering, late-tillering, and early-heading growth stages, respectively. Both herbicides were applied singly or sequentially at 70, 140, and 280 g/ha. Sequential applications of fluazifop and quizalofop at 280 g/ha caused the greatest reduction of red rice panicle and seed production. Fluazifop at 280 g/ha applied sequentially reduced panicle production 75 to 80% and seed production 80%; 140 g/ha applied sequentially reduced seed production 83%. Quizalofop at 280 g/ha applied sequentially reduced panicle production 75 to 100% and seed production 91%. Sequential applications of either herbicide applied to red rice plants in the panicle initiation and early-heading growth stages were the most effective treatments.

Sensitivity of Grass Crops to Low Rates of Quizalofop

“…Chlorosis and eventual necrosis develop 1 to 3 wks after application (Ahrens 1994). Research has shown that quizalofop is effective in controlling both barnyardgrass (Noldin et al 1998) and red rice (Salzman et al 1988). In soybean, quizalofop is applied at from 35 to 84 g ai ha –1 (Shaner 2014), but labeled use rates in quizalofop-resistant rice could be as high as 138 g ha –1 for single application (Anonymous 2017).…”

Graminicide Application Timing Influences Red Rice (Oryza sativa) Control and Seedhead Reduction in Soybean (Glycine max)1

“…Red rice control from single applications of many selective grass herbicides is often inconsistent (Khodayari et al 1987;Salzman et al 1989). In most cases, consistency and increased control were achieved with sequential herbicide applications (Barrentine et al 1984;Salzman et al 1988;). a Data are averages of responses from five separate herbicide treatments.…”

“…Adequate moisture for red rice growth and reproduction is important in upland nonirrigated environments. Moisture stress affects seedhead development of red rice and domestic rice (De Datta 1981;Salzman et al 1988Salzman et al , 1989.…”

“…Graminicides such as clethodim, fluazifop-P, quizalofop-P, and sethoxydim are effective for control and seedhead suppression of red rice (Guy and Helms 1995;Salzman et al 1988) with herbicide efficacy dependent on application timing. Control is often reduced by environmental conditions, such as drought that stresses treated plants or subsequent rainfall that causes new seedlings to emerge.…”

Weed Seed Bank Dynamics

“…Herbicide applications that do not kill plants may also reduce seed production. Sublethal doses of herbicide reduced seed production of several weed species by as much as 90% (Biniak and Aldrich, 1986;Salzman, Smith, and Talbert, 1988). Although seed production in most weed species can be reduced by management factors, seed production will likely be adequate, even with moderate weed infestations, to allow rapid increases in the seed bank (Schweizer and Zimdahl, 1984;Hartzler, 1996).…”