During propagation, leaves may become blighted and cuttings may rot. On potted poinsettias, tan to brown lesions form on leaves, stems and bracts. Extensive tan cankers can form on stems when Botrytis enters via blighted petioles or shoots. Lesions begin at the margins of bracts, turning darker as they expand. Latex may exude from the undersides of lesions.
Sporulation develops on the necrotic areas under humid conditions.
Bracts and flowers of poinsettias are particularly prone to infection by Botrytis . Control of Botrytis is challenging because of its abilities to survive as a saprophyte, rapidly invade host tissues and quickly produce abundant conidia that are easily distributed by air currents. Sanitation alone is not sufficient for minimizing Botrytis blight losses in the greenhouse. Prevention should be the main focus of a Botrytis management program. An integrated strategy combining environmental management, cultural practices, and fungicides will most effectively manage this omnipresent threat in the greenhouse.