Botrytis blight was observed on geranium leaves submitted to the UMass Extension Plant Diagnostic Lab this week. Botrytis has a wide host range and can affect all plant parts. The leaf lesions caused by this fungus may begin as brown, water-soaked areas. Eventually, fuzzy gray spores can be seen with a hand lens or the naked eye. Greenhouse sanitation, good air circulation, and keeping the plant canopy dry are critical for Botrytis management.
For more information, see the fact sheet: https://ag.umass.edu/greenhouse-floriculture/fact-sheets/botrytis-blight-of-greenhouse-crops