Botrytis (fungus)
Botrytis is a group of fungi in the family Sclerotiniaceae, commonly known as grey mold. There are about 30 species in this genus, and the most familiar one is Botrytis cinerea, a plant pathogen that causes gray mold on many plants and fruits.
Botrytis cinerea affects a wide range of hosts, including ornamental plants such as geraniums, begonias, roses, lilies, rhododendrons, dahlias, magnolias, and camellias, as well as various fruits and produce. It can come from outdoor plants but may grow on fruits or flowers brought indoors, and some houseplants (like cyclamen, poinsettia, chrysanthemums, and gerberas) can also be affected.
The fungus forms dark, branching conidiophores that carry clusters of pale gray conidia, which give the characteristic moldy appearance. The disease is favored by cool, damp conditions and can spread rapidly in humid environments. Botrytis is primarily a parasite of living plant tissue but can also live as a saprophyte on dead material.
Other Botrytis species include B. peoniae on peonies, B. squamosa on onions, and B. tulipae on tulips. The name Botrytis comes from Greek words meaning “grapes,” referring to the clustered conidia.
Conidia are colorless to gray-brown, smooth, and typically nonseptate, while conidiophores are gray to brown, often branched, with a long stalk and a dense head. Although identifying the genus is usually straightforward, distinguishing species by conidia in samples can be difficult.
No mycotoxin has been reported from Botrytis, but exposure to its spores can trigger hay fever, asthma, or eye infections in sensitive individuals.
This page was last edited on 2 February 2026, at 18:00 (CET).