Anthracnose is a fungal disease that occasionally causes damage in high-rainfall areas. Anthracnose on alfalfa is caused by a different fungus than northern anthracnose on clover. These spots are straw coloured with darker borders. Damage occurs when the spots expand and girdle stems, causing dead shoots in the summer and fall. Anthracnose can also cause a crown rot.
Stems broken off at crown level have a bluish-black discoloration at the base.
Most varieties have at least a moderate level of resistance. For information on resistant varieties, contact your district agriculturist. If anthracnose is suspected, clean plant debris from harvesting equipment after cutting infected fields to minimize spread to healthy fields. Sclerotinia Crown and Stem Rot Sclerotinia stem rot. Whitish fungal growth and black sclerotia on lower stems.