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Fungus, Hypomycete

Latin name : Helminthosporium solani

Diagnostic characters for visual diagnosis

• Silvery lesions with well defined edges
• Edge of lesion brown and of irregular width
• Lesions may coalesce
• Conidiophores develop at edge of lesion
• Typical shape of conidophores: pine trees
• When severely infected, tubers lose moisture rapidly and may appear wrinkled

Notes on confirmatory diagnostics

• After incubation of infected tuber at high relative humidity,  the microsclerotia produce conidiophores recognizable under the microscope

• For the fungus isolation, pick tissue from edge of lesion after surface sterilization

• Potato Dextrose Agar (PDA) is a good isolation medium

Specific reference :

Errampalli et al  (2001). Plant Pathology, 50, 141-153

Black dot

Golding blotch