Silver scurf – Helminthosporium solani

Symptoms   Seldom seen at harvest, symptoms are grey or silvery patches on the skin.  The silvery appearance becomes more noticeable during storage especially in warm, humid conditions and the edges of the lesions develop a sooty appearance.

Sources and Factors Favouring Development

Infection is caused mainly by planting infected seed tubers; seed showing slight infection may cause more infection on the daughter tubers than severely infected seed, as younger lesions sporulate more profusely than older ones.

Control          Plant in rotated sites as soil borne inoculum is likely to decrease in the absence of potato tubers. Harvest fields in a timely manner to limit the disease levels before storage. Store tubers at the lowest temperature possible (as soon as practical after harvest) given the market requirement. Relative humidity should also be kept low although this may increase losses to Black dot.  The use of an approved fungicide early in the storage period provides a very high degree of control on the resulting progeny.