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United States Department of Agriculture

Agricultural Research Service

Research Project: Mitigating Agricultural Sources of Particulate Matter and Greenhouse Gas Emissions in the Pacific Northwest

Location: Northwest Sustainable Agroecosystems Research

Title: Weed-suppressive bacteria to reduce annual grass weeds

Authors
item Stubbs, Tami -
item Hansen, Jeremy
item Kennedy, Ann

Submitted to: Washington State University College of Agriculture and Home Economics
Publication Type: Experiment Station
Publication Acceptance Date: June 1, 2014
Publication Date: N/A

Technical Abstract: Cheatgrass (Bromus tectorum L.), medusahead (Taeniatherum caput-medusae [L.] Nevski) and jointed goatgrass (Aegilops cylindrica L.) are exotic, annual grasses that negatively affect cereal production in cropland; reduce protein-rich forage for cattle; choke out native plants in the shrub-steppe habitat of the western United States rangeland; reduce habitat for sagebrush-dependent wildlife; and increase fire frequency of these lands. These weeds produce the fuel for wildfires that destroy property and result in loss of life. Naturally occurring bacteria from the soil and root surface have been found to inhibit these invasive weeds. These weed-suppressive bacteria: 1) are applied in the fall and establish in the soil microbial community as weather cools; 2) inhibit radicle formation, root growth and tiller initiation of these weeds; 3) do not injure native plants or crops; 3) grow well in fall and spring during the early root growth of the annual weeds; and 4) grow along roots, which then deliver the weed-inhibitory compound. Certain soil bacteria inhibit only: 1) cheatgrass (downy brome), 2) medusahead, 3) jointed goatgrass, and 4) do not inhibit any economically important or native plants. Replicated field plots across the west show that the bacteria consistently reduce annual grass weed growth by 50% within three years of one bacterial application. The bacteria reduced these fall annual grass weeds to near zero, when desirable plants (winter wheat, perennial bunchgrasses, natives) were present. Because of their selectivity, these bacteria can be used in management of the invasive weeds cheatgrass, medusahead and jointed goat grass in rangeland, cropland, pasture, turf, sod production, golf courses, road sides and road cuts, construction sites, and right-of-ways (road, rail, pipeline, electrical).

Last Modified: 10/21/2014
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