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Fungus, Adelomycete = Deuteromycete

Latin name : Colletotrichum coccodes

Other names : Anthracnose

Diagnostic characters for visual diagnosis

• Diffuse brown  lesions with black microsclerotia regularly spaced.
• The lesions are irregularly shaped with less well-defined margins than silver scurf. Lesions may coalesce to form larger areas
• Sclerotia develop into acervuli producing conidia
• Black dot symptoms may be present at harvest but can develop during storage
• Sunken lesions may occur after cold storage

Notes on confirmatory diagnostics

• Incubating infected tubers at high relative humidity, microsclerotia produce silks with a sea urchin appearance observable under a hand  lens
• For isolation, pick up tissue from edge of lesion after surface sterilization
• Malt & PDA are good isolation media                                                                                                  

Specific reference :

Glais-Varlet & Andrivon (2004). Plant Pathology, 53, 254

Silver scurf

Golding blotch