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. Scattered plants turn yellow, then wilt and die. A white, cottony growth of mycelium is visible on the lower stems and crowns during cool, wet weather.
Infected stems become soft and mushy at the base.
Crown infection leads to plant death. Small, hard, black sclerotia are produced on or inside stem and crown tissue. Snow cover increases the development of Sclerotinia crown and stem rot during the winter. Sclerotinia is less damaging to alfalfa than to clovers. Use sclerotia-free seed to avoid introducing the disease.