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United States Department of Agriculture

Agricultural Research Service

Title: Field Efficacy of Selected Nonpathogenic Fusarium Spp. and Other Biocontrolagents for the Control of Fusarium Wilt of Tomato, 1997-1998

Authors
item Larkin, Robert
item Fravel, Deborah

Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 15, 1999
Publication Date: N/A

Interpretive Summary: Field plots were established to evaluate the efficacy of beneficial microbes (biocontrol agents) for the control of Fusarium wilt of tomato. Nonpathogenic F. oxysporum (CS-20) and F. solani (CS-1) and the commercial biocontrol agent SoilGard (SG; Gliocladium virens strain Gl- 21, Thermo Trilogy Corp., Columbia, MD), all previously shown to reduce Fusarium wilt in greenhouse tests, were tested alone and in various combinations. In 1998, an additional combination treatment, consisting of a fungus (G. virens Gl-3) and a bacterium (Burkholderia vietnamiensis Bc-F), was also tested. Biocontrol agents were added at seeding and prior to transplanting into a field with natural plus artificial inoculum of the pathogen. The weight and number of tomatoes were recorded weekly. At the end of the season, stem sections from all plants were placed on a Fusarium-selective medium to determine how many plants were infected with the pathogen. In 1997, little disease developed, with no differences observed among treatments. In 1998, all biocontrol treatments involving F. oxysporum isolate CS-20 (CS-20, CS-1+CS-20, and SG+CS-20) and the fungus plus bacterium treatment (G+B) significantly reduced disease incidence relative to the pathogen control. However, only CS-20 and G+B treatments had significant effects on yield, exhibiting increased total weight, number of tomatoes, and average weight per tomato compared to the pathogen control. Biocontrol treatments CS-20 and G+B increased total weight 34.3 and 37.7% and total numbers 28.2 and 32.2%, respectively, relative to the pathogen control. SG and CS-1 alone had no significant effect on disease incidence or yield. This information will be used by scientists developing environmentally benign controls for Fusarium wilt.

Technical Abstract: Field plots were established to evaluate the efficacy of selected biocontrol agents for the control of Fusarium wilt of tomato. Isolates of nonpathogenic F. oxysporum (CS-20) and F. solani (CS-1) and the commercial biocontrol agent SoilGard (Gliocladium virens strain Gl-21, Thermo Trilogy Corp., Columbia, MD), all previously shown to reduce Fusarium wilt in greenhouse tests, were tested alone and in various combinations in 1997 and 1998. In 1998, an additional combination treatment, consisting of a fungus (G. virens strain Gl-3) and a bacterium (Burkholderia vietnamiensis strain Bc-F), was also tested. Biocontrol agents were added at seeding and prior to transplanting into a field with natural plus artificial inoculum of the pathogen. The weight and number of fruit were recorded weekly. At the end of the season, stem sections from all plants were surface-sterilized and plated on a Fusarium- selective medium to determine the incidence of plants systemically infected by the pathogen. In 1997, little disease developed, with no differences observed among treatments. In 1998, all biocontrol treatments involving F. oxysporum isolate CS-20 (CS-20, CS-1+CS-20, and SG+CS-20) and the fungus plus bacterium treatment (G+B) significantly reduced disease incidence relative to the pathogen control. However, only CS-20 and G+B treatments had significant effects on yield, exhibiting increased total weight, number of fruits, and average weight/fruit compared to the pathogen control. Biocontrol treatments CS-20 and G+B increased total weight 34.3 and 37.7% and total numbers 28.2 and 32.2%, respectively, relative to the pathogen control. SoilGard and CS-1 alone had no significant effect on disease incidence or yield.

Last Modified: 4/23/2014