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ARS Home » Midwest Area » East Lansing, Michigan » Sugarbeet and Bean Research » Research » Publications at this Location » Publication #317358
Title: A Colletotrichum sp. causing root rot in sugar beet (Beta vulgaris)

Author
item Hanson, Linda
item NEHER, OLIVER - Amalgamated Sugar Company

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2015
Publication Date: 11/1/2015
Citation: Hanson, L.E., Neher, O.T. 2015. A Colletotrichum sp. causing root rot in sugar beet (Beta vulgaris). Phytopathology. 105:S4.5-6.

Interpretive Summary:

Technical Abstract: In fall of 2014 sugar beets were observed in a field in Washington State with shallow, dark, firm lesions on the surface. When examined under magnification, minute black “dots” were observed on the surface of the lesions. Isolations were made from the lesions and a Colletotrichum species was consistently isolated from all lesions sampled. The Colletotrichum produced black sclerotia on and adjacent to which were produced conidiomata with setae and hyaline, straight spores when grown on Malt extract agar or water agar. When sugar beet stecklings of four different USDA germplasm were inoculated with 10 ml of a spore suspension of 10^4 spores per ml as a soil drench, all germplasm developed symptoms by 5 weeks after inoculation. One germplasm had less than 10% of the root surface with lesions while the other three germplasm all had 40-50% of the root surface with shallow, dark firm lesions with minute black “dots". A Colletotrichum sp. that was morphologically identical to the initial isolate was re-isolated from inoculated plants. Control plants (a soil drench with sterile water) did not show symptoms and did not yield Colletotrichum. Colletotrichum has not previously been reported on sugar beet in the United States and the Colletotrichum isolates are not C. dematium, the species reported on beet in other countries. An additional field in Idaho was subsequently identified with similar symptoms and research is ongoing to determine the species involved.