Sclerotium rolfsii is a soilborne fungus that attacks plant tissues at or near the soil surface. This fungus can be recognized by the dense mold growth that imparts a white-washed appearance to colonized stem tissues. When abscised or fallen leaves or other debris is present, the mold may grow profusely over the soil surface. Entire limbs on plants may wilt and die as a result of the fungus decaying stems near the crown of plants.


After the stem rot fungus has killed peanut tissues and consumed all available food, the fungus produces survival structures, called sclerotia. These structures are round and resemble mustard seed in size, and are white at first, then become tan and finally dark brown when mature. Sclerotia resemble seeds in that they remain dormant until stimulated to germinate. Sclerotia germination appears to be triggered by substances emitted from abscissed peanut leaves or other organic matter near the soil surface. Mold board plowing to bury organic matter or old crop debris, followed by good leafspot and weed control, and non-dirting cultivation are important practices in preventing the triggering of stem rot epidemics.