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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #389588
Research Project: Development of Management Strategies for Livestock Grazing, Disturbance and Climate Variation for the Northern Plains

Location: Livestock and Range Research Laboratory

Title: Low rate of aminopyralid nearly eliminates viable seed production in barb goatgrass (Aegilops triuncialis)

Author
item Rinella, Matthew - Matt
item Bellows, Susan - Bartlett
item BEITZ, PAMELA - East Bay Regional Park District

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2022
Publication Date: 3/7/2022
Citation: Rinella, M.J., Bellows, S.E., Beitz, P.A. 2022. Low rate of aminopyralid nearly eliminates viable seed production in barb goatgrass (Aegilops triuncialis). Invasive Plant Science and Management. 15:57-60. https://doi.org/10.1017/inp.2022.3.
DOI: https://doi.org/10.1017/inp.2022.3

Interpretive Summary: Barb goatgrass is an invader of Mediterranean annual grasslands and serpentine soil plant communities in the western U.S. It has little value as a forage plant, and there are downsides and challenges to controlling it with prescribed fire, mowing and grazing. One herbicide option is glyphosate, but it can damage native forbs and forage grasses. Grass-specific herbicides are another option, but they also pose risks to forage grasses and may be ineffective unless applied at rates exceeding U.S. Environmental Protection Agency guidelines.

Technical Abstract: Invasive annual grasses such as medusahead (Taeniatherum caput-medusae [L.] Nevski) and barb goatgrass (Aegilops triuncialis L.) are negatively impacting grasslands of the western U.S. Over the last decade, research has shown that aminopyralid and other growth regulator herbicides applied just prior to flowering greatly reduce seed production in several invasive annual grasses. Moreover, with medusahead, it’s been shown that using aminopyralid to reduce seed production one year consistently reduces and sometimes nearly eliminates cover the following year. Our goal in this study was to extend this research to barb goatgrass, a weed for which limited herbicide and other management options exist. Based on previous research, we hypothesized aminopyralid applied several days before flowering at just 22% of the maximum registered rate (0.069 kg ae ha-1) would almost completely prevent seed production in the greenhouse. In four experiments, aminopyralid reduced seed viability from between 65 and 95% to between 1 and 5%. Therefore, aminopyralid will likely control barb goatgrass in the field. Because aminopyralid is phytotoxic to many broadleaf species, it may be possible to use aminopyralid to simultaneously control mixed stands of invasive forbs, barb goatgrass and medusahead. However, there are risks to applying aminopyralid where desirable nonnative and native forbs occur. Past research on medusahead suggests controlling barb goatgrass with aminopyralid will increase desirable annual forage grasses.