Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2012
Publication Date: April 1, 2013
Citation: Wedge, D.E., Curry, K.J., Kreiser, B., Curry, A., Abril, M., Smith, B.J. 2013. Fungicide resistance profiles for 13 Botrytis cinerea isolated from strawberry in southeastern Louisiana. International Journal of Fruit Science. 13(4):413-429. Interpretive Summary: This paper reports on the occurance of fungicide resistant Botrytis cinerea that causes gray mold of strawberries and many other crops. Botrytis cinerea has become resistant to several commonly used fungicides classes including the benzimidazoles and dicarboximides. Recently several new fungicides have become available and are very effective for control of Botrytis diseases (i.e., strobirulins, anilides, and pyrroles); however, the development of isolates of Botrytis cinerea resistant to these new chemicals is a concern for growers. Our results indicate that Botrytis isolates from strawberry in southeastern Louisiana are resistant to benzimidazole fungicides and are becoming resistant to dicarboximide fungicides.
Technical Abstract: BACKGROUND: Fungicidal sprays have been widely used for disease control of gray mold caused by Botrytis cinerea. In recent years strawberry growers in southeastern Louisiana reported a failure of their fungicide spray programs to control Botrytis fruit rot. Botrytis cinerea has become resistant to several commonly used fungicides classes including the benzimidazoles and dicarboximides. Sensitivity/resistance profiles were established for each of the 13 Botrytis isolates to eleven fungicides based on mean percent growth inhibition/stimulation values obtained using the 96-well microtiter system in B. cinerea populations from farms where Botrytis fruit rot control was poor. RESULTS: Micro-dilution broth results indicated that Botrytis isolates from strawberry in southeastern Louisiana are resistant to benzimidazole fungicides and are becoming resistant to dicarboximide fungicides. Louisiana Botrytis isolates were of three phenotypes: benzimidazole and dicarboximide resistant, benzimidazole resistant and dicarboximide sensitive, and those with benzimidazole and dicarboximide intermediate resistance. CONCLUSION: While the use of a 3-point assay has many disadvantages typical of most in vitro studies, it provided useful resistance and sensititive information in a timely basis. Combining or alternating fungicides is an important management strategy to prevent the development of fungicide resistant pathogens which is one of the most difficult problems of chemical disease management.