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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #135344


item Kremer, Robert

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2006
Publication Date: N/A
Citation: N/A

Interpretive Summary: Some bacteria in soils may express beneficial traits including growth suppression of weeds. These bacteria may be extracted from soil, multiplied in the laboratory, and used to manage weeds in fields on a regional scale. However, before such bacteria are used widely, they must be tested rigorously to assure only weeds are attacked and not crop, ornamental, or native plants. We tested a large collection of bacteria from roots of weeds (rhizobacteria; RB) for ability to suppress the growth of weeds but not crops. About 75% of RB inhibited growth of important weeds (foxtail, field bindweed, redroot pigweed) and not of wheat or soybean. One RB agent not only suppressed growth of four weeds but also promoted growth of wheat and soybean, indicating potential as a "dual purpose" biological agent. Because the RB that were most inhibitory to weeds were from fields under sustainable management (low chemical inputs, organically amended, crop rotation), selection of certain cultural practices may promote weed suppressive RB directly in the field. Results are important to scientists and producers because safe and effective products and/or practical guides for enhancing biocontrol of weeds in the field will reduce reliance on herbicides and enhance soil and environmental quality.

Technical Abstract: Selected bacterial isolates previously demonstrated to be suppressive toward weed species in the laboratory were tested for effectiveness under greenhouse conditions. Rhizobacteria varied in ability to inhibit growth of host or other weed species. Some bacterial isolates caused up to 75% growth inhibition, while some isolates were unable to express inhibitory effects under greenhouse conditions. Host specificity of isolates also varied with some isolates significantly suppressing growth of host plants, as well as other weed species, and occasionally crop plants. Isolates that only inhibited growth of weed plants without negatively affecting crop plants are considered candidates for further tests as potential biological control agents. Because potential biological control agents would encounter more complex interactions with indigenous microorganisms and environmental factors when applied in the field, the greenhouse test is an important step in documenting the effectiveness and host specificity of deleterious rhizobacteria.