Weed-Suppressive Bacteria Have No Effect on Exotic or Native Plants in Sagebrush-Steppe |
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Affiliation: | 1. Plant Physiologist, Northwest Watershed Research Center, US Department of Agriculture (USDA)−Agricultural Research Service (ARS), Boise, ID 83712, USA;2. Ecologist, Range and Meadow Forage Management Research Unit, USDA-ARS, Burns, OR 97720, USA;3. Professor, Department of Environment and Society, Utah State University, Logan, UT 84322, USA;4. Assistant Professor, Department of Economics, University of Nevada, Reno, NV 89557;5. Rangeland Management Specialist, Southern Plains Range Research Station, Woodward, OK 73801;1. US Department of Agriculture (USDA)−Agricultural Research Services (ARS), Great Basin Rangelands Research Unit, Reno, NV 89512, USA;2. Rangeland Management Specialist, USDA-ARS, Great Basin Rangelands Research Unit, Reno, NV 89512, USA;3. Planner & Environmental Specialist, Medford/Ashland BLM, Medford, OR 97504, USA;4. Rangeland Scientist Technician, USDA-ARS, Great Basin Rangelands Research Unit, Reno, NV 89512, USA;5. Agricultural Science Research Technician, USDA-ARS, Great Basin Rangelands Research Unit, Reno 89512, NV, USA.;1. Graduate Research Assistant, Bioagricultural Sciences and Pest Management Department, Colorado State University, Fort Collins, CO 80523, USA;2. Research Associate, Bioagricultural Sciences and Pest Management Department, Colorado State University, Fort Collins, CO 80523, USA;3. Professor and Extension Specialist, Bioagricultural Sciences and Pest Management Department, Colorado State University, Fort Collins, CO 80523, USA |
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Abstract: | Approaches and techniques for control of exotic annual grasses are a high priority in rangelands including sagebrush steppe. Strains of the soil bacterium Pseudomonas fluorescens have been proposed to be selectively pathogenic to multiple species of exotic annual grasses (“Pf,” weed-suppressive bacteria, “WSB”). However, defensible tests of the target and nontarget effects of these WSB strains in the field are needed. We evaluated the effects of D7 and MB906 strains of Pf WSB in sagebrush steppe invaded by cheatgrass (Bromus tectorum L), medusahead (Taeniatherum caput-medusae L. Nevski), and other exotic annual grasses. We evaluated the WSB strains with and without herbicides (imazapic, rimsulfuron) or discing to mix surface-spray of the WSB into deeper soils, and we replicated these tests in three ecoregions that differed in soils and climate. Over 3 yr after treatment, neither WSB strain affected cover of exotic annual grasses, perennial bunchgrasses, or the total community, either with WSB alone or in combination with herbicides or discing. WSB has received considerable attention and is being applied across large rangeland areas, but the WSB strains and methods applied here were ineffective. We recommend any future use of WSB be applied in an experimental fashion, with experimental design and measurement of responses, until its effects can be proven. |
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Keywords: | biocontrol biopesticides exotic annual grasses perennial grasses weed-suppressive bacteria |
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