Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: 8/19/1998
Publication Date: N/A
Technical Abstract: Current biological control of economically important weeds is primarily through host-specific insects and mycoherbicides consisting of fungal pathogens, which often require specific conditions and repeated applications to be successful. An alternative biological control strategy using selected microorganisms originating from soils and rhizospheres of the target weeds for attacking roots may effectively decrease vigor of weeds without the environmental manipulations needed to assure efficacy of the agents. With the emphasis on developing sustainable agriculture systems for protecting environmental quality, the role of rhizobacteria as potential natural biocontrol agents of weeds has increased. The objectives of this research were to survey bacteria inhabiting soils and rhizospheres of economically important weeds and examine the microbial collection for potential biocontrol activity. Preliminary lettuce seedling bioassays indicated that 62 and 54% of rhizosphere and endorhizal bacteria, respectively, significantly inhibited root growth and caused necrotic lesions. We have tested over 500 bacterial isolates for potential biocontrol activity. Results of our survey suggest that weed rhizospheres and associated soils are good sources of potential biological control microorganisms and merit consideration for inclusion in comprehensive and sustainable management programs for economically important weeds.