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Michigan Grape Facts: Managing Botrytis Bunch Rot


June 24, 2020 - <> and <>


  • Botrytis cinerea
  • Kingdom: Fungi
  • Division: Ascomycota
  • Class: Leotiomycetes
  • Asexual form: Botrytis cinerea
  • Sexual form: Botryotinia fuckeliana or also known as Botryotinia cinerea


Botrytis cinerea, or the causal agent of gray mold and bunch rot, is one of the most important pathogens of grapes worldwide. B. cinerea is a necrotrophic fungus that attacks and infects all different parts of the grape vines; however, fruit rot is the most problematic. Botrytis bunch rot infection can cause huge economic losses in grape production due to the preharvest infection in the field, which leads to reduced yield and postharvest losses during storage. Warm and wet weather (59 to 68 degrees Fahrenheit; 15 to 20 degrees Celsius, at least 90% humidity) are inducive to B. cinerea infection and spread.



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