LINCOLN, Neb. (AP) — A fast-growing weed that can devastate corn and soybean yields has resumed its march across Nebraska and other agriculture-heavy states. Palmer amaranth, long the scourge of cotton-growing states in the South, has been making its way north as seeds hitch rides on harvesting equipment or mingle with cotton seed hulls used for livestock feed.

The Lincoln Journal Star reports that new infestations of Palmer amaranth have been reported in Minnesota and Iowa. An Iowa State professor reported earlier this month that the plant has been confirmed in 49 Iowa counties.

Chemical weapons in the war against the weed have begun to fail as it quickly develops resistance. Many farmers have returned to more expensive means of control: hand weeding.