[Image: Plant symptoms of Cotton Root Rot]Symptoms
Above-ground symptoms, which occur around mid-season, include a sudden wilting of foliage followed by rapid death of entire plant within a few days. Leaves shrivel, turn brown and die, but they remain attached to the plant. Often a white mat of fungal growth is visible around the base of the plant. A red to burgundy lesion is visible below the bark on the lower stem near the soil line. The roots may be covered with brown thread-like strands of the fungus.
Causal Agent and Disease Development
Cotton root rot or Texas root rot is caused by the fungus Phymatotrichopsis omnivora. The disease is common on cotton in parts of Texas, hence its name. In Louisiana, the disease is present only in two fields in Caddo and Bossier parishes. Symptoms are not visible until mid season during boll development. Losses are high because entire plants are killed quickly.
Control
Fortunately, Texas root rot is not widespread in Louisiana, because control is difficult. Management mostly relies on cultural practices, such as rotations and tillage, to reduce the severity of the disease. Corn, sorghum and small grains are not susceptible to the disease and are good crops to include in rotations. Deep plowing [Image: Strands of fungus on infected root]to expose the survival structures of the fungus to drying will reduce the severity of the disease. Green manuring and other practices that increase organic matter in the soil reduce growth of the fungus and disease development.