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United States Department of Agriculture

Agricultural Research Service

Title: Efficacy of Various Fungal and Bacterial Biocontrol Organisms for the Control of Fusarium Wilt of Tomato

Authors
item Larkin, Robert
item Fravel, Deborah

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 9, 1998
Publication Date: N/A

Interpretive Summary: Fusarium wilt disease, caused by pathogenic forms of the soil-inhabiting fungus Fusarium oxysporum, is a major disease problem on tomato and many other crops. Currently, control of this pathogen on tomato is generally provided by soil fumigation with methyl bromide. However, in addition to other potential health, safety, and environmental effects, methyl bromide is classified as an ozone-depleting compound and is scheduled to be remove from the market in the U.S. by 2001. Thus, alternative control measures are needed. This research explores the potential of biological control for the management of this disease. Numerous fungi and bacteria, including existing biocontrol strains with known activity against soilborne pathogens and isolates collected from the roots of tomato plants in the field, were tested for their efficacy in controlling Fusarium wilt of tomato in greenhouse tests. Organisms tested included nonpathogenic strains of Fusarium spp., Trichoderma spp., Gliocladium virens, Pseudomonas fluorescens, Burkholderia cepacia, and others. Specific nonpathogenic isolates of F. oxysporum and F. solani collected from a Fusarium wilt-suppressive soil were the most effective antagonists, providing significant and consistent disease control (50-80% reduction of disease incidence) in several repeated tests. Various other organisms also significantly reduced Fusarium wilt (30-60% reduction), but were not as consistently effective as the nonpathogenic Fusarium isolates. Specific isolates of nonpathogenic Fusarium spp. have potential for development as biological control agents for the control of Fusarium wilt. This research benefits scientists, private industry, and growers interested in commercial development and use of biological agents for the control of plant diseases.

Technical Abstract: Numerous fungi and bacteria, including existing biocontrol strains with known activity against soilborne fungal pathogens and isolates collected from the roots and rhizosphere of tomato plants growing in the field, were tested for their efficacy in controlling Fusarium wilt of tomato. Tomato seedlings were treated with the potential biocontrol agents in the greenhouse and transplanted into pathogen-infested field soil. Organisms tested included nonpathogenic strains of Fusarium spp., Trichoderma spp., Gliocladium virens, Pseudomonas fluorescens, Burkholderia cepacia, and many others. Specific nonpathogenic isolates of F. oxysporum and F. solani collected from a Fusarium wilt-suppressive soil were the most effective antagonists, providing significant and consistent disease control (50-80% reduction of disease incidence) in several repeated tests. These isolates also were equally effective in controlling Fusarium wilt diseases of other crops, including watermelon and muskmelon. Other organisms, including isolates of G. virens, T. hamatum, P. fluorescens, and B. cepacia, also significantly reduced Fusarium wilt compared to disease controls (30-60% reduction), but were not as consistently effective as the nonpathogenic Fusarium isolates. Several fungal and bacterial isolates collected from the roots and rhizosphere of tomato plants also significantly reduced Fusarium wilt of tomato, but were no more effective than other previously identified biocontrol strains. Combinations of antagonists, including multiple Fusarium isolates, Fusarium with bacteria, and Fusarium with other fungi, also reduced disease, but did not provide significantly better control than the nonpathogenic Fusarium antagonists alone.

Last Modified: 8/29/2014