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Title: FIELD EFFICACY OF SELECTED NONPATHOGENIC FUSARIUM SPP. AND OTHER BIOCONTROLAGENTS FOR THE MANAGEMENT OF FUSARIUM WILT OF MUSKMELON, 1997-1998

Author
item Larkin, Robert - Bob
item Fravel, Deborah
item KATHERINE, EVERTS - UNIV. OF MD, SALISBURY

Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Field plots were established to evaluate the efficacy of beneficial microbes (biocontrol agents) for the management of Fusarium wilt of muskmelon. The field was naturally infested with two races of the fungal wilt pathogen F. oxysporum f. sp. melonis. Isolates of nonpathogenic F. oxysporum (CS-20) and F. solani (CS-1), previously shown to reduce Fusarium wilt in greenhouse tests, were tested alone and in combination in 1997 and 1998. In 1998, an additional combination treatment, consisting of a fungus (Gliocladium virens strain Gl-3) and a bacterium (Burkholderia vietnamiensis strain Bc-F), was also tested. Biocontrol agents were added at seeding and prior to transplant. At the end of the season, stem sections from all plants were surface-sterilized and plated on a Fusarium-selective medium to determine how many plants were infected by the pathogen. Yield was measured as the total weight and the total number of melons per plot combined over several individual harvest dates. In both 1997 and 1998, symptoms of Fusarium wilt developed slowly, with little disease apparent until late in the season. Based on stem platings, all biocontrol treatments significantly reduced disease incidence relative to the nontreated control in both 1997 and 1998 tests, with disease reductions averaging 38-43% in 1997 and 42-59% in 1998. However, due to the late development of disease, there were no differences in yield (either total weight or number of melons per plot) among any treatments in either year. This information will be used by scientists developing environmentally benign control measures for use against Fusarium wilt.

Technical Abstract: Field plots were established to evaluate the efficacy of selected biocontrol agents for the management of Fusarium wilt of muskmelon. The field was naturally infested with races 1 and 2 of the wilt pathogen F. oxysporum f. sp. melonis. Isolates of nonpathogenic F. oxysporum (CS-20) and F. solani (CS-1), previously shown to reduce Fusarium wilt in greenhouse tests, were tested alone and in combination in 1997 and 1998. In 1998, an additional combination treatment, consisting of a fungus (Gliocladium virens strain Gl-3) and a bacterium (Burkholderia vietnamiensis strain Bc-F), was also tested. Biocontrol agents were added at seeding and prior to transplant. 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. Yield was measured as the total weight and the total number of harvestable fruit per plot combined over several individual harvest dates. In both 1997 and 1998, symptoms of Fusarium wilt developed slowly, with little disease apparent until late in the season. Based on systemic infection by the pathogen, all biocontrol treatments significantly reduced disease incidence relative to the nontreated control in both 1997 and 1998 tests, with disease reductions averaging 38-43% in 1997 and 42-59% in 1998. However, due to the late development of disease, there were no differences in yield (either total weight or number of fruit per plot) among any treatments in either year.