noun
1. : any of several diseases of plants marked by light-colored lesions: as
a. : a disease of alfalfa characterized by spotting and yellowing of the foliage and caused by an unbalanced water supply (as from heavy rainfall following a drought)
b. : heat canker
c. : a disease of turnips caused by a fungus ( Cercosporella brassicae )
2. : ich — usually used in plural