Pellicularia is a genus of fungi that infect plants and causes root rot, crown rot and damping off of seeds. According to "Westcott's Plant Disease Handbook," there is some disagreement about how to name Pellicularia diseases, and you may see terms such as southern blight, athelia, rhizoctonia and sclerotium that refer to the same pathogen.
Pellicularia causes several diseases. Crown rot causes stems just above the soil line to rot, turning the leaves yellow and causing them to wilt. Root rot causes deterioration of the root system, again appearing as wilted, yellowing leaves. Damping off occurs when the fungus infects seeds or seedlings, causing failed germination or visible decay of emergent seedlings. These diseases can be caused by fungi other than Pellicularia
Described by "Westcott's Plant Disease Handbook," Pellicularia infection begins with a cottony substance called mycelium that spreads across the soil at the base of the plant and may begin to climb the stem. As the infection progresses, small red-brown structures called sclerotia develop, often so heavily that they cover the top of the soil. During the early stages of sclerotia development, drops of liquid appear on the fungus. This liquid kills plant cells and allows the fungus to infect a range of species. Visible plant structures may show signs of rot, and all plants begin to wilt, lose vigor and eventually die. However, since root rot and damping off can be caused by several different fungi, soil testing is necessary to determine the exact pathogen, especially if you intend to use a fungicide.
Fruits, vegetables and ornamental plants are all susceptible to the diseases caused by Pellicularia.
The University of Florida IFAS Extension urges gardeners to take steps to prevent Pellicularia-related infections. Because the fungus prefers warm, humid conditions, poor cultural practices or poorly drained soil are often to blame for infections. Do not overwater. Incorporate organic material into dense soils to improve drainage. Because the fungus transmits on garden tools, sterilize all digging tools in a diluted bleach solution.
If a soil test identifies the precise pathogen afflicting your plants, approved fungicides may control the spread of the disease to other plants. The Missouri Botanical Garden recommends removing all diseased plants as soon as problems are noticed. They may be buried but should not be composted. Either dig out and replace the soil to 8 inches deep and 6 inches beyond the place of infection, or solarize the soil by covering it with black plastic for two to three months in direct summer sunlight.