Features

• The Phymatotrichum omnivorum fungus causes cotton root rot. The fungus, a soil-borne organism, produces root-like fungal strands that grow through the soil and colonize the roots of plants. Phymatotrichum omnivorum prefers clay or loamy alkaline soils and hot summer temperatures. Cotton root rot is most virulent between June and September when the temperatures are highest.
  
  

Effects

• Cotton root rot infects and decays the roots of plants. The host plant is unable to absorb water through its roots and wilts in the hot weather, resulting in sudden plant death. The disease causes a slow decline in cooler temperatures. According to the University of Arizona Cooperative Extension, mature trees may be infected for long periods of time without showing any symptoms, but die quickly during hot summer temperatures as their need for water increases.
  
  

Prevention/Solution

• There is no way as of 2010 to test the soil for the presence of the cotton root rot fungus. Chemical controls have limited success. Avoid cotton root rot by planting tolerant or immune species.