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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #363125
Research Project: Adaptive Rangeland Management of Livestock Grazing, Disturbance, and Climatic Variation

Location: Livestock and Range Research Laboratory

Title: Synthesis of weed-suppressive bacteria studies in rangelands of the western United States: Special section of articles in Rangeland Ecology & Management provides little evidence of effectiveness

Author
item Reinhart, Kurt
item CARLSON, CHRIS - Montana Conservation Science Institute
item FERIS, KEVIN - Boise State University
item GERMINO, MATT - Us Geological Survey (USGS)
item JANDREAU, CLANCY - Montana Conservation Science Institute
item LAZARUS, BRYNNE - Us Geological Survey (USGS)
item MANGOLD, JANE - Montana State University
item PELLATZ, DAVE - Thunder Basin Grasslands Prairie Ecological Association
item RAMSEY, PHILIP - Mpg Ranch
item Rinella, Matthew - Matt
item VALLIANT, MORGAN - Montana Conservation Science Institute

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2020
Publication Date: 11/1/2020
Citation: Reinhart, K.O., Carlson, C.H., Feris, K.P., Germino, M.J., Jandreau, C.J., Lazarus, B.E., Mangold, J., Pellatz, D.W., Ramsey, P., Rinella, M.J., Valliant, M. 2020. Synthesis of weed-suppressive bacteria studies in rangelands of the western United States: Special section of articles in Rangeland Ecology & Management provides little evidence of effectiveness. Rangeland Ecology and Management. 73(6):737-740. https://doi.org/10.1016/j.rama.2020.02.007.
DOI: https://doi.org/10.1016/j.rama.2020.02.007

Interpretive Summary: • Background- Downy brome infests millions of acres of western rangelands. Microbes have been proposed as a tool to manage and control downy brome. • Problem- Most research demonstrating the effectiveness of weed-suppressive bacteria (WSB) rely on highly controlled Petri-plate and pot experiments conducted in growth chambers. Field experiments are rare, mostly from Washington state, and reveal mixed results. • Accomplishment- We used a series of experiments to test the effectiveness of WSB on downy brome from Montana and Wyoming. In highly controlled Petri-plate experiments, WSB inhibited downy brome from Montana and Wyoming. We detected no WSB effects in more realistic experiments using downy brome growing in pots containing field soil and field experiments across sites in Montana and Wyoming. • Rangeland management implications- Given the expense of acquiring and applying WSB, we recommend against using currently available WSB strains for controlling downy brome without prior controlled and replicated studies that include monitoring to ensure effectiveness at a given site.

Technical Abstract: The exotic winter annual grass Bromus tectorum (downy brome or cheatgrass) infests millions of ha of western rangelands. Weed-suppressive bacteria (ACK55 and D7 strains of Pseudomonas fluorescens) have been shown to reduce B. tectorum populations in eastern Washington, USA. Unfortunately, outside of Washington, little is known about the efficacy of these or other weed-suppressive bacteria. We used Petri-plate and plant-soil bioassays to test effects of ACK55 and D7 on B. tectorum from Montana and Wyoming. We also tested effects of ACK55 on B. tectorum at six field sites in Montana and one in Wyoming. P. fluorescens reduced B. tectorum germination and root and shoot lengths in Petri-plates but had no effect on plants during growth chamber plant-soil bioassays or field experiments. Bromus arvensis, a species similar to B. tectorum, was prevalent at two of our sites, and ACK55 was ineffective against B. arvensis as well. Our findings contribute to a growing body of evidence that the ACK55 and D7 strains of P. fluorescens are not a reliable tool for controlling B. tectorum in the Northern Great Plains and Central Rocky Mountains and elsewhere.