Disease

Gray mold (Botrytis)

Botrytis cinerea

A fungus that infects flowers, dense buds, ripe fruit, wounds and dying tissue in cool, humid, still air. It spreads by masses of airborne spores and can rot fruit after harvest.

Signs

• Gray to brown fuzzy mold.
• Tan, water-soaked rot starting at spent petals, wounds or inside tight flower buds.
• Flowers that turn brown and die.

What favors it

Relative humidity above about 85%, cool temperatures, condensation, dense canopies, and dead or wounded tissue.

Prevention

• Keep humidity below about 85% and avoid moisture on plant surfaces; run fans for air movement.
• Remove spent flowers, dead leaves and plant debris promptly.
• Space and prune for airflow; avoid wounding stems.

Often confused with

Sources

• Gray mold in the flower gardenUniversity of Minnesota Extension
• Gray mold of tomatoesUniversity of Minnesota Extension
• Botrytis Gray Mold in Greenhouse Floral CropsOhio State University Extension

Why →