Impact
Silver scurf, caused by the fungus Helminthosporium solani, is a common disease in most potato producing areas. Silver scurf can drastically lower market quality of tubers. This disease is difficult to manage. As a result of imported seed, silver scurf has become a more important disease in the San Luis Valley in recent years.

Silver scurf.

Descriptions and Symptoms
	Spread of the fungus to daughter tubers is largely from infected seed pieces; soil transmission also is a factor.
	Infections become more severe the longer the tubers remain in the soil.
	Infections occur in the field as tubers mature. Symptoms may be present on tubers at harvest or may develop on tubers in storage.
	Infected areas have a distinct silvery sheen, particularly if the surface is wet.
	Infected tubers well shrivel during storage from excessive water loss.
	High humidity and temperatures above 40 degrees F foster silver scurf development in storage.
	Tuber to tuber spread in storage is common.
Integrated Management
	Use high-quality, certified seed. Note: This practice will not offer 100 percent control.
	Harvest as soon as adequate skin set has been achieved.
	Ventilate storage areas with cool air for drying. Store tubers at the lowest possible termperature consistent with the intended end use.
	No pesticides are presently available for effective control.
	Rotate crops and potato cultivars.

This material is based on work supported by the San Luis Valley Water Quality Demonstration Project Best Management Practices Advisory Committee, Colorado State University Cooperative Extension, Farm Service Agency, Natural Resources Conservation Service, and the U.S. Department of Agriculture under authorization as 1991 U.S. Department of Agriculture Water Quality Demonstration Project.