Infections can occur anytime during a growing season. Early infection causes the most damage, because both roots and culms are affected. Infections when the plant is approaching maturity are usually confined to root tissue and cause only minor damage. Root infection is favored by cool, moist soil conditions. The most obvious symptom of take-all root rot is the development of white heads during the grain filling period.
Infection usually attacks patches of plants that become stunted.
Roots of affected plants are dark brown to black because of fungal invasion. As the plant matures, its roots become rotten and brittle until the plant can be easily pulled from the soil. Barley, triticale, and rye are all susceptible to take-all root rot. In order of susceptibility, wheat is most susceptible, followed by barley, oats, triticale, and rye, which is least susceptible. Crop rotation is the best control for take-all root rot.