Michigan's 45,000 acres of potato plants are being closely monitored. Farmers and scientists are watching for the fungus known as "Potato Late Blight". It destroys the potato plant, spreading by seeds and even air.
MSU scientist Willie Kirk says Michigan farmers spend $4 million a year to fight the disease. But if left unchecked, Kirk says the fungus could destroy the entire U.S. potato crop.
Potato Late Blight was responsible for the Irish potato famine of 1845.