disease_substrate_wood
wood|branches
Root rot, crown rot, stem blight and leaf spot. In alfalfa the taproot, crown, branches, and leaves are affected. The leaf spots are circular to irregular, light buff to greyish-white, 2-10 mm wide, sometimes involving the entire leaflet, with or without concentric bands, but always with a reddish-brown border. Usually pycnidia occur in the paler central areas of the spots. The visible symptoms on roots are smooth dark brown to black lesions which later dry, crack and become roughened. Beneath the surface the tissues turn reddish-brown to almost black. As the disease progresses slowly a dry rot develops followed by the appearance in the bark of a reddish colour which extends into the decaying wood rays. No new buds are formed and the plant eventually dies (18, 320). On species of Melilotus leaf spots have been reported as abundant in early spring and late in the fall in the U.S.A. In one variety of sweet clover only leaf spots have been reported abundant in the mid summer. The fungus enters roots through wounds.
Depazea meliloti
Longiseptatispora meliloti