Blight has been found in potato crops in the Red River Valley, raising fears of widespread damage.
Northern Plains Potato Growers Association President Chuck Gunnerson said several cases of blight have been found. He said weather over the next three weeks will determine how quickly the disease spreads.
"If we could have 95 degree temperatures, dry, wind, we could slow this down tremendously," Gunnerson said. "But if we continue to have the weather we've been having which has been cool, damp, rainy, it could be devastating for us."
Potato blight was reported in several states and Canada this year.
Gunnerson said it's believed the disease came from tomato plants sold by several large national retail stores.
"Tomatoes were shipped out of Alabama this year and went through distributors such as Walmart, Kmart and various others," Gunnerson said. "There was late blight on those tomatoes and we feel that [it] is the possible cause that is creating all the late blight scares up and down the United States."
The late blight fungus is the same organism that caused the famous Irish potato famine in the mid 1800s.
The last outbreak of potato blight in Minnesota and North Dakota in 1999 destroyed an estimated $125 million worth of potatoes.