Black leg (stem canker)

The first obvious symptom of blackleg of oilseed rape (rapeseed) (Brassica napus, B. rapa, and some other Brassica spp.) caused by the fungus Leptosphaeria maculans, is the appearance of gray-green to ash-gray lesions on the lower leaves. The presence of small, black pycnidia at the edge or scattered across the blackleg lesions distinguishes them from lesions caused by another common foliar pathogen, Alternaria brassicae.

• Reference: http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/Pages/Blackleg.aspx

Presence among species

Pathogen	Susceptible Host
Leptosphaeria maculans	Arabidopsis thaliana