September 9, 2009
Late blight caused the 19th century famine that sparked a wave of emigration from Ireland to the United States, but the disease has also infected tomatoes and potatoes this year. Potatoes, the world's fourth-largest food crop, were raised on 65,500 acres in Wisconsin in 2007. If a potato field is not treated with pesticide, late blight can destroy the crop in a few days.