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United States Department of Agriculture

Agricultural Research Service

Title: Combinations of Biocontrol Agents for Management of Plant-Parasitic Nematodes and Soilborne Plant-Pathogenic Fungi

Authors
item Meyer, Susan
item Roberts, Daniel

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 28, 2001
Publication Date: March 1, 2002
Citation: Meyer, S.L., Roberts, D.P. 2002. Combinations of biocontrol agents for management of plant-parasitic nematodes and soilborne plant-pathogenic fungi. Journal of Nematology 34: 1-8.

Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plants, causing seven billion dollars in annual crop losses in the U.S. Plant- pathogenic fungi cause even greater crop losses. Many fungi and bacteria are active against these disease-causing organisms, but few biocontrol agents are sold for management of plant diseases. One obstacle to commercial production of biocontrol agents has been inconsistent action against nematodes and fungi. A suggested strategy for overcoming inconsistent performance is to combine two (or more) beneficial microbes in a biocontrol preparation. The question addressed in this review is: Can such combinations provide more effective management of nematodes, resulting in reduced crop losses? Compared with biocontrol agents applied alone, combinations might grow more extensively on plant root surfaces, be effective under a broader range of soil conditions, and show activity against a larger number of plant pests or pathogens. However, microbes applied together may also act against each other. Increased, decreased, and unaltered action against plant disease agents have been observed when microbe combinations have been applied for plant health management. Unfortunately, the ecological basis for increased or decreased activity has not been determined in many cases. Work in this area is significant because the approach may overcome some of the problems that occur with application of individual biocontrol agents. This research will be used by scientists developing environmentally safe methods for managing diseases caused by nematodes and fungi in the soil.

Technical Abstract: Numerous microbes demonstrate antagonism to plant-parasitic nematodes and soilborne plant-pathogenic fungi, but few of these organisms are commercially available for management of these plant pests. Inconsistent performance of applied biocontrol agents has proven to be a primary obstacle to the development of successful commercial products. One of the strategies for overcoming inconsistent performance is to combine the disease suppressive activity of two (or more) beneficial microbes in a biocontrol preparation. Such combinations have potential for more extensive colonization of the rhizosphere, more consistent expression of beneficial traits under a broad range of soil conditions, and antagonism to a larger number of plant pests or pathogens than strains applied individually. However, microbes applied in combination may also have antagonistic interactions with each other. Increased, decreased, and unaltered suppression of the target pathogen or pest have been observed when microbe combinations have been applied for plant health management. Unfortunately, the ecological basis for increased or decreased suppression has not been determined in many cases, and needs further consideration. The complexity of studies on preparations containing combined biocontrol organisms slows progress towards development of a successful formulation. However, this approach has potential for overcoming some of the efficacy problems that occur with application of preparations containing individual biocontrol agents.

Last Modified: 7/22/2014
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