1 (white blister) A disease affecting brassicas and other plants, caused by species of the genus Albugo. White, blister-like spots are formed on the leaves, and infected plants may show some distortion.
2 A disease of chrysanthemums caused by Puccinia horiana. Buff or white pustules appear on the under-sides of the leaves and may become brown and necrotic (see necrosis). This disease first appeared in Britain in 1963 and is now a notifiable disease.