Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: November 13, 1995
Publication Date: N/A
Interpretive Summary: Biological weed control, the use of naturally-occurring organisms to manage weed populations, is an attractive alternative weed control approach. Biological control organisms can self-perpetuate after introduction into weed infestations, and chemicals potentially harmful to the environment are not used. Unfortunately, few biological control agents used as independent tweed management approaches have been successful in managing weeds. Strategies are needed to improve the effectiveness of biological control. Integration of biological control in current weed management systems rather than developing independent approaches centered on the agents may be most efficient in the short-term. For example, low amounts of herbicides can induce weeds to be more susceptible to many biological control microbes thereby enhancing overall weed control while requiring less chemical input into the environment. Other approaches include combining specific insects and microbes for increased attack on selected weeds and using biocontrol agents with certain crop varieties that are antagonistic to weeds. These novel approaches for getting biological control into current weed management systems should increase acceptance of alternatives to chemical-based crop production and reduce environmental impacts of herbicides.
Technical Abstract: Development of environmentally safe alternative weed management strategies is limited by a lack of knowledge in two main areas. These include an understanding of ecological and biological factors that affect dynamics of weed growth and populations and the ecology and biology of microorganisms that interact with weeds at various growth stages. Such knowledge is required to properly fit biological approaches into weed management systems. This paper assesses the known relationships between soil and rhizosphere microorganisms and weeds and describes potential weed management strategies based on these relationships. Limited studies indicate that certain conditions including cultural practices, agrichemical application, and vegetative residue placement contribute to rhizosphere microbial shifts responsible for weed seedling growth inhibition. Activity of potential weed-attacking rhizosphere bacteria may be enhanced through improved formulations and delivery methods, combination with other biocontrol agents, and designing microbial combinations for specific soil regions and weed populations. The best opportunity for success will be through integration of selected microorganisms or microbial combinations with other weed management practices, including reduced herbicide applications, cover crop/mulching systems, crop rotations, and use of highly competitive crop varieties.