Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 20, 2003
Publication Date: November 29, 2003
Citation: Howell, C.R., Puckhaber, L.S., Stipanovic, R.D. 2003. Biocontrol of pre-emergence cotton seedling disease by metabolism of pathogen germination inducers [abstract]. American Phytopathological Society Abstracts. 93(6):S37. Technical Abstract: Pre-emergence damping-off of cotton seedlings by Pythium spp. and Rhizopus oryzae is initiated by the production and release of compounds from the germinating seed that induce resting structures of the pathogens to germinate and grow. Cotton cultivars are quite variable with respect to the production and release of inducer compounds. Those cultivars that release inducers are highly susceptible to disease, while those that do not release inducers are virtually immune. Once pathogen germination has been induced, all cultivars are susceptible. Seed treatment of susceptible cultivars with biocontrol preparations of Trichoderma virens prevents pre-emergence damping-off in cotton. When pathogen inducers present in seed exudates are exposed to propagules of T. virens in culture, their capacity to induce germination of pathogen propagules is destroyed. Inducer compounds exposed only to culture filtrates from T. virens are not adversely affected. Inducer compounds are not extractable from seed exudate with immiscible organic solvents, indicating that they are not the fatty acid compounds previously reported.