Black root rot is more severe when lesion nematodes are present. The characteristic action of this fungus is to destroy the fine feeding roots, causing the plant to show symptoms of drought and low nutrition. The plant may not die. The infected roots show a dry, brown decay of the fleshy part of the root, which finally is entirely disintegrated. The central cylinder remains enclosed in a tube of the root epidermis like a wire running through a pipe.
Black root rot is difficult to control.
Current recommendations include avoiding heavy wet soils and reducing plant stress. Preplant fumigation may give partial control in the first year. Rotation out of strawberries for at least two years can help reduce some of the pathogens. Research in Connecticut has shown that fertilizing strawberries with ammonium sulfate will suppress black root rot. Red stele, Phytophthora fragariae.