Potato Silver Scurf

Potato Silver Scurf is a fungal blemish disease of potato tubers caused by Helminthosporium solani. The pathogen causes tan-to-gray circular lesions typically initiating on the stem-end of the tuber surface, often appearing shiny and silver when wet. The pathogen survives on infected tubers and infested plant debris, spreading via rain/irrigation in the field and airborne spores in storage. Favorable conditions include high temperatures and humidity. Infection reduces both the visual appeal of a fresh market potato tuber and reduces the quality of potato tubers as the infection creates damage to the periderm or skin which enables the onset of other pathogens or enhanced desiccation.

Cultural management involves using clean, uninfected seed potatoes, rotating planting sites, promptly harvesting fields after potato foliar senescence, disinfecting storage facilities, and maintaining properly cold and ventilated storage areas. Seed-applied, in-furrow, and post-harvest fungicides can also reduce disease incidence. This disease is primarily a concern for stored, commercial fresh market potatoes.

Silver scurf lesions on a potato tuber
Silver scurf lesions on a potato tuber. Photo Credit: Amanda J. Gevens, UW Extension.