Silver scurf, caused by a fungus, is a common potato disease and found in all major production areas of the United States, including the Red River Valley of western Minnesota and northeast North Dakota.

“Whodunnit? Is it a silver scurf problem? Or is it a black dot problem,” she said. “It’s hard to tell these apart. Sometimes you can’t tell them apart.”

One important difference: silver scurf is tied to infected seed, while black dot is more of a soil/field debris issue, Gevens said.

Use of uninfected seed, which can be hard to get, helps to control the disease, as does early harvest and chemical use,

Storage conditions also influence the extent of silver scurf in affected potatoes. “High humidity in storage encourages it,” Gevens said.

Research also shows that smaller storage volumes help to control core temperatures and hold down silver scurf. But limiting storage volumes may not always be feasible, she said.