Red root rot is first caused by a variety of soilborne pathogens that weaken the root system, allowing for easy access by the true red root rot pathogen. This pathogen is able to adapt to a wide range of temperatures and soil conditions where it can last for many years before infecting its host. Infection usually begins no earlier than midsilking in corn, or early August.
Symptoms of red root rot are generally not apparent until the fungus has significantly reduced the health of the plant. The base of the stalk as well as the roots are usually changed to a pinkish red color. If compared to healthy plants, the infected root bundle is visibly reduced in total mass. The symptoms in foliage are very similar to other stalk rot diseases: grayish and wilted leavees. Foliar effects are noticed 4-5 days after infection, and the plant death along with lodging occur 2 to 5 days after foliage symptoms appear. Not to be confused with Gibberella stalk rot, the red root rot discoloration is a much deeper red.