Botrysis blight on begonia
Updated: March 18, 2021

Symptoms of gray mold on indoor plants

  • Gray mold or Botrytis blight often begins with relatively large grayish to tan areas on older leaves or spent flowers.

  • The dusty gray spores of the fungus are easily seen and infected areas can rapidly enlarge and cause tissue collapse.

  • This fungus primarily infects older tissue and generally is not a serious pathogen unless infection conditions are ideal.

  • Optimum infection conditions would include wet leaves, high humidity, cool temperatures and cloudy overcast days.

Management strategies

  • Any method that will lower the humidity, decrease leaf wetness or increase air circulation will help to lessen the chances of infection.

  • Watering should be done early in the day to allow leaf surfaces time to dry quickly.

  • Space plants so that air can circulate between them to help reduce moisture.

  • Registered fungicides can be used, but in most home conditions, removal of infected plant parts and adjustment of environmental conditions to drier conditions should help manage this disease.