The fungus is prevalent in calcareous clay loam soils with a pH range of 7.0 to 8.5 and in areas with high summer temperatures. Therefore, the disease is limited to the southwestern United States. Phymatotrichum root rot has been reported in Texas counties from the Red River to the Rio Grande and from Tom Green County to the Neches River. The first symptoms are slight yellowing or bronzing of leaves followed by wilting. Plants die suddenly after the first symptoms of wilting.
Leaves remain firmly attached to the plant.
Affected plants die suddenly, often after excellent growth. Large trees and shrubs may die more slowly. Usually roots are invaded extensively by the fungus by the time plants have wilted. When roots are pulled from the soil, root bark is decayed and brownish, and wooly strands of the fungus frequently are apparent on the root surface. Affected plants pull from the soil with little effort.