SCLEROTIUM • DICTIONARY ONE.COM • Definition of Sclerotium

... mycelium which, after a few days, bears numerous round shot-like bodies, at first light-colored, then becoming smaller and dark-brown. These are the sclerotia or resting bodies of the fungus. This fungus, called Sclerotium sp., or "Rolf's Sclerotium," is noteworthy because it attacks potatoes, squash, cowpea, and a long list of other garden vegetables and ornamental plants. The only satisfactory means of control is rotation of crops, using corn, small grain, and the Iron cowpea, a variety immune ...

— Tomato Culture: A Practical Treatise on the Tomato • William Warner Tracy