Alternaria leaf spot, gray leaf spot or black leaf
spot (Alternaria brassicae, A. brassicicola, and A.
raphani) – Seedborne
Alternaria leaf spot is caused by any of three
Alternaria species, all of which cause similar
symptoms on radish. The host is susceptible at all
stage of growth, with cycles of infection favored
by frequent and long periods of leaf wetness. On
seedlings, stem lesions (dark spots) can result in
seedling death. On leaves, lesions are tan, brown,