Pyroxsulam Compared with Competitive Standards for Efficacy in Winter Wheat

Abstract

Field studies at six locations over 3 yr in Kansas compared pyroxsulam at two application timings to competitive standards for winter annual weed control in winter wheat. Pyroxsulam applied fall-POST (FP) controlled downy brome 84 to 99% and was similar to or greater than sulfosulfuron, propoxycarbazone, or propoxycarbazone plus mesosulfuron. Downy brome control was lower when application timing was delayed until spring (SP), such that no herbicide provided more than 90% downy brome control. Cheat control was 97% or more with almost all herbicides applied FP, and greater than 90% in most locations when herbicides were applied SP. Sulfosulfuron was the exception with only 30 to 81% cheat control. All FP-applied herbicides, except sulfosulfuron at Manhattan, KS, controlled blue mustard 95% or more. Pyroxsulam and propoxycarbazone plus mesosulfuron FP completely controlled henbit at Hesston, KS, in 2009, but no herbicide treatment provided more than 60% control when applied SP. Averaged over application timings, pyroxsulam provided the greatest henbit control (76 and 78%) at Manhattan and Hays, respectively, in 2009, and FP treatments were 33 and 28 percentage points more effective than SP treatments at those locations. Averaged over application timing, wheat yields did not differ between herbicide treatments in five of six locations. Averaged over herbicide treatment, FP-treated wheat yielded more grain than SP-treated wheat at three of the six locations.

Downy Brome (Bromus tectorum L.) and Broadleaf Weed Control in Winter Wheat with Acetolactate Synthase-Inhibiting Herbicides

“…Control of henbit with spring treatments was 49% compared to 80% with fall treatments. Our results are in agreement with previous reports on decreased blue mustard and henbit control with delayed ALS-inhibiting herbicide applications [11]. …”

“…In 2010-2011, pyroxsulam and propoxycarbazone-Na controlled downy brome (72% and 77%, respectively) better than propoxycarbazone-Na & mesosulfuron-methyl (57%) or sulfosulfuron (63%). In a similar study also in Kansas, pyroxsulam applied in fall controlled downy brome similar to or greater than propoxycarbazone-Na, propoxycarbazone-Na & mesosulfuron-methyl, and sulfosulfuron [11]. In our study, averaged over treatments, downy brome control decreased when application timing was delayed until spring (Table 4).…”

“…Blackshaw and Hamman (1998) [18] reported more than 85% downy brome control with sulfosulfuron at 19 to 33 g ai ha −1 applied fall-POST, whereas spring-POST application of sulfosulfuron at 60 g ai ha −1 only suppressed growth of downy brome. Geier et al (2011) [11] also reported better downy brome control with all four ALS-inhibiting herbicides tested in our study when applied in fall than spring. …”

“…These herbicides provide good broadleaf weed control efficacy, but have little or no activity on brome species (Bromus spp.) [11]. Sulfosulfuron, propoxycarbazone-Na, and pyroxsulam selectively control both grass and broadleaf weeds in wheat.…”

“…Sulfosulfuron, propoxycarbazone-Na, and pyroxsulam selectively control both grass and broadleaf weeds in wheat. Sulfosulfuron (Maverick ® , Monsanto Company, 800 N. Lindbergh Blvd., St. Louis, MO 63167, USA), a sulfonylurea herbicide, was introduced in 1998 [12] and was the first herbicide registered primarily to control winter annual grasses in wheat [11]. Propoxycarbazone-Na (Olympus [15]; it belongs to the triazolopyrimidine sulfonamide family of herbicides.…”