ARS | Publication request: EXPERIMENTAL TEST OF MICROBIAL BIOCONTROL OF CHEATGRASS

Submitted to: Bureau of Land Management
Publication Type: Government Publication
Publication Acceptance Date: March 19, 2002
Publication Date: March 19, 2003
Citation: Weddell, B.J., Kennedy, A.C. Frohne, P.S. and Higgins, S. Experimental test of microbial biocontrol of cheatgrass. pp.22-26. In: Restoring Palouse and Canyon Grasslands: Putting back the missing pieces. Bureau of Land Management Report, Cottonwood, ID. Technical Bulletin No. 01-15. 2001.

Interpretive Summary: The establishment of non-native annual grasses in disturbed rangelands is a major challenge when restoring native bunchgrass vegetation. Bacteria that inhibit weedy species have potential in weed management strategies. The use of soil bacteria for biocontrol of weeds has not been fully investigated and is an area that needs further research. We tested the impact of a weed- inhibitory bacterium on the germination and emergence of cheat grass in a heavily infested site near Pullman, WA. We did not find a reduction in weed populations due to the application of the strain. We did not test the vigor of the plants. The site was heavily infested with weeds and the bacterium may not have able to reduce populations in the first year when many plants are present. Bacteria as bioherbicides or natural components of the soil microbial community may play a major role in reclaiming and restoring soil quality and biodiversity to ecosystems degraded through continuous implementation of conventional cropping systems.

Technical Abstract: The establishment of alien annual grasses in disturbed Palouse and Canyon Grassland presents a major challenge for restoration of native bunchgrass vegetation. One promising area of research involves manipulating the microbiota of the rhizosphere to control weeds. Deleterious rhizobacteria (DRB) colonize the rhizosphere and suppress plant growth. These bacteria have often been overlooked because of their subtle effect on plant growth. These organisms can influence the distribution, abundance, and competition among plant species. Inoculation of soil with Pseudomonas fluorescens strain D7 did not adversely affect the number of perennial grasses in this experiment. We did not analyze for plant vigor. The densities of the downy brome in the test plots were high, indicating that in heavily infestations it might take multiple years with successive applications for any inhibitory effects to appear.