Submitted to: Methyl Bromide Alternatives and Emissions Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 28, 1996
Publication Date: N/A
Technical Abstract: Our previous work identified two strains, CS-1 and C-20, of nonpathogenic Fusarium oxysporum that effectively controlled Fusarium wilt on tomato and other crops. Split-root tests indicated that the mechanism of these two antagonists is induced systemic resistance. Inoculum densities of CS-20 as low as 100 chlamydospores/g soil effectively controlled Fusarium wilt at all pathogen levels tested (up to 10**5), while CS-1 was effective only at densities of 500 or more cfu/g soil and at pathogen densities less than 10**4 cfu/g soil. Isolate CS-20 was effective in a variety of soil types, including a sandy loam with low organic matter (OM), a loamy soil with high OM, and a heavy clay soil, whereas isolate CS-1 was effective in all but the clay soil. Isolates CS-20 and CS-1 were also effective in controlling disease caused by several different isolates of pathogenic races 1, 2, and 3 in all tests. In preliminary tests, combinations of multiple antagonists sdid not enhance the level of control provided by F. oxysporum isolates alone. Our results indicate that these beneficial isolates, and particularly CS-20, have potential for development as biological control agents. Research will continue to evaluate ecological conditions for optimal disease control, to field test these antagonists, integrate these biocontrol agents with other control measures, and to develop methods for production and formulation.