Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: January 10, 2005
Publication Date: March 1, 2005
Citation: Hanson, L.E., Davidson, R.M., Franc, G.D., Panella, L.W. 2005. Analysis of benzimidazole-tolerance in Cercospora beticola. Proc. American Society of Sugarbeet Technologists. 33rd Meeting (Agriculture) Palm Springs, CA. March 2-5, 2005. Annual Meeting abstract p. 179. 2005. Technical Abstract: Cercospora beticola causes Cercospora leaf spot (CLS) of sugar beet and several other hosts in the Chenopodiaceae. On sugar beet, CLS is the most important foliar disease worldwide. The primary disease management methods are host resistance and foliar fungicide treatments. Benzimidazole fungicides target beta-tubulin and are used in some production regions for disease control. However, benzimidazole use is increasingly limited as benzimidazole-resistance becomes more widespread in the pathogen population. We examined isolates of C. beticola from different years and production regions for sensitivity to benzimidazole fungicides and for their beta-tubulin gene sequence. Isolates with benzimidazole-tolerance had a mutation in the beta-tubulin gene that corresponded to mutations previously determined to confer benzimidazole-tolerance in other ascomycete fungi. This same mutation has been shown to confer sensitivity to N-phenylcarbamates (NPC). When our C. beticola isolates were tested for sensitivity to the NPC fungicide diethofencarb, benzimidazole-tolerant isolates proved sensitive to the NPC, while benzimidazole-senstive isolates showed little or no sensitivity to the NPC. C. beticola isolates collected in the central High Plains region of the United States in 2004 are being tested for their response to benzimidazoles and NPC, and a PCR-based method for detection of benzimidazole sensitivity is being investigated.