ARS | Publication request: Control of Downy brome (Bromus tectorum) and Medusahead (Taeniatherum caput-medusae) With Rangeland Herbicides in Northeastern California

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 5, 2009
Publication Date: February 7, 2010
Citation: Zhang, J., Kyser, G., Wilson, R., Creech, E., Weltz, M.A., Clements, D.D., Ditomaso, J. 2010. Control of Downy brome (Bromus tectorum) and Medusahead (Taeniatherum caput-medusae) With Rangeland Herbicides in Northeastern California [abstract]. Society for Range Management and Weed Science Society of America Annual Meeting Program Guide. P B-9.

Technical Abstract: Downy brome and medusahead are the most problematic invasive annual grasses in rangelands of the western United States. In this study, we evaluated the effect of three fall-applied, and one spring-applied, herbicides or combinations on the control of these two invasive grasses in a sagebrush community in northeastern California. The study also included an untreated control and the experiment was repeated at two sites within 8 km of each other. The experiment was a complete randomized block design with four replications per site. Each plot was 30 x 30 m. Herbicides were applied by backpack sprayer at the following rates: 93 g ae/ha imazapic, 17.5 g ai/ha rimsulfuron, 35 and 17.5 g ai/ha, respectively, sulfometuron + chlorsulfuron, 420 g ae/ha glyphosate. All treatments were made in September to early November, 2008, except glyphosate (mid-April 2009) and plots were evaluated in June 2009. Plant species cover was estimated using point-intercept transects, and biomass samples were taken each plot. Chlorsulfuron + sulfometuron provided 100% control of the two invasive annual grasses at both sites, but also damaged resident perennial grasses and caused some injury to sagebrush. In contrast, rimsulfuron gave 100% control of downy brome and an average of 96% control of medusahead without damaging perennial grasses or sagebrush. Imazapic and glyphosate were inconsistent, providing between 29% and 100% control of the two grasses, depending on the site. Our results indicate that rimsulfuron is a very effective tool for invasive annual grass control without damaging desirable perennial grasses or sagebrush.