Aphanomyces root rot is caused by the fungus-like pathogen Aphanomyces cochlioides. Seedling infection occurs optimally when soil temperatures are less than 60ēC. The pathogen survives between sugarbeet crops as dormant resting structures (oospores) in soil and pathogenically on weeds.
Aphanomyces root rot rarely causes pre-emergence damping off, but soon after emergence the pathogen invades the cortex of the hypocotyl, causing a brown discoloration, which can advance up to the base of the cotyledon. Seedlings may become flaccid, fall over, and die, but often recover. Plants are dwarfed and seldom produce normal mature plants. Yield losses can be significant.
No biological control strategies have been developed for Aphanomyces root rot.
Plant high quality seed into warm, well prepared seedbeds that encourage rapid germination. Avoid excess irrigation and poor drainage. Rotation with dryland crops before sugarbeets may reduce damage. Some varieties are less susceptible or resistant to Aphanomyces root rot, but most are susceptible to the disease.
Treat seed with a broad-spectrum fungicide such as hymexazol (tachigaren). In furrow phosphorous fertilization combined with seed treatment may improve disease control.
Categories: Sugarbeet, Diseases, Aphanomyces Root Rot
Date: 03/27/05