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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Sublethal Stresses on Microsclerotia of Verticillium Dahliae

Authors
item Fravel, Deborah
item Larkin, Robert

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 28, 1999
Publication Date: N/A

Interpretive Summary: The possibility of combining biocontrol by the beneficial fungus Talaromyces flavus with sublethal levels of heat or fumigation to achieve control of the soilborne wilt pathogen Verticillium dahliae with minimal environmental disruption is being investigated. Previous studies demonstrated that sublethal heat or fumigation acted additively with T. flavus to kill the survival structures (microsclerotia) of V. dahliae. The current study demonstrated that microsclerotia of V. dahliae that were weakened by refrigerated storage were more easily damaged by stresses from hydrogen peroxide, the soil fumigant metham sodium, or heating than expected. The nutrient content of the medium on which the microsclerotia were grown also altered their susceptibility to hydrogen peroxide. Progeny of microsclerotia which survived sublethal stresses developed resistance to these stresses within a few generations when the stress was applied to each generation. However, if the stress was applied only to every second or third generation, resistance did not develop. This information will be used to develop management strategies for Verticillium wilt.

Technical Abstract: The possibility of combining biocontrol by Talaromyces flavus with sublethal levels of heat or fumigation to achieve control of the soilborne wilt pathogen Verticillium dahliae with minimal environmental disruption is being investigated. Previous studies demonstrated that sublethal heat or fumigation acted additively with T. flavus to kill microsclerotia of V. dahliae. The current study demonstrated that microsclerotia of V. dahliae that were weakened by storage at 4 C were more easily damaged by stresses from hydrogen peroxide, metham sodium, or heating than expected. The nutrient content of the medium on which the microsclerotia were grown also altered their susceptibility to hydrogen peroxide. Progeny of microsclerotia which survived sublethal stresses developed resistance to these stresses within a few generations when the stress was applied to each generation. However, if the stress was applied only to every second or third generation, resistance did not develop. This information will be used to develop management strategies for Verticillium wilt.

Last Modified: 10/24/2014
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