ST. PAUL, Minn. (AP) — The Minnesota Department of Agriculture has confirmed a new discovery of the aggressive weed Palmer amaranth, this time in Douglas County of western Minnesota.

The find means the weed, which has long been a scourge in cotton-growing southern states, has now turned up in four Minnesota counties. The others are Lyon, Todd and Yellow Medicine.

Palmer amaranth grows fast and tall. It's notoriously hard to eradicate and can slash corn and soybean yields. All of Minnesota's infestations have been found in conservation plantings of seed mixtures that apparently were contaminated. But the department says it has made good progress toward eradicating finds that turned up last year in Lyon and Yellow Medicine counties.

Fortunately, no Palmer amaranth has been found in Minnesota row crop fields, which could be economically harmful.