Phomopsis spp. causes forsythia and azaleas to develop abnormal growths or galls. (It can also be found on weeping figs growing inside buildings as house plants.)
Galls can be as small as a pea to as big as an inch or more. The size of the gall varies with plant infected, the age of the plant tissue and where on the plant infection occurs. In general the galls are "round" and are found singly or in small clusters. On forsythia, the galls are often clustered.
The fungus lives for several years in the galls before dying. Little is known about the life cycle of this pathogen.
Prune out and destroy infected plant tissue.