The bud is destroyed. It frequently hangs over at or near the lesion. The fungus may also infect stub ends of stems from which flowers have been cut. Botrytis is a gray fungus that generally lives on dying tissue. With the right conditions, any dead plant tissue can release thousands of Botrytis spores.
Botrytis infection occurs when water remains on leaves or buds.
To prevent large numbers of fungal spores, remove dead plant material on which spores are produced. Fungicide application may be necessary. A preventive spray program can include chemicals listed in table 1. Brown Canker is caused by the fungus Cryptosporella umbrina . The disease is commonly found on outdoor roses and occasionally on greenhouse-grown roses.