Palmer Amaranth Is For Real

This weed nightmare won't have a happy ending unless scouting is taken seriously.

Published on: Jul 31, 2013

Maybe you're thinking Palmer amaranth is like soybean rust and it won't ever get here. Several years ago the fear over soybean rust reached near hysteria-levels. The truth is, it is in the South, but because people made such an effort to monitor for it, it seldom gets far enough north early enough in the season to cause any real yield loss.

Palmer amaranth is not soybean rust. It is not only coming, it is here. A Purdue University weed control specialist has documented it in 17 counties. Another report adds Fulton County, for a total of 18 counties. Samples in at least some counties are resistant to glyphosate. Some are resistant to other chemistries as well.

One southeastern Indiana ag dealer recently told a company rep that they have it and it's no big deal. The rep assured him that if he thinks it's no big deal, he doesn't have it. It can be mistaken for pigweed or waterhemp, which are close but less aggressive cousins.

Super weed: They wont make a movie about it or call it the weed of steel, but Palmer amaranth may be the toughest weed Hoosiers have battled in years, if ever. Take precautions now.
Super weed: They won't make a movie about it or call it the 'weed of steel,' but Palmer amaranth may be the toughest weed Hoosiers have battled in years, if ever. Take precautions now.

Palmer Amaranth, however, is so aggressive that one specialist in another state says it even choked out a stand of waterhemp, thought to be a tough competitor itself.

The first step is to identify it, specialists say. It has a long narrow stem leading off the main stem to a petiole. The seed head is extremely long, longer than any seedhead you've seen on other weeds in Indiana. The roots grow huge, and they do it in a hurry.

Your option at this point is to scout for it. If you see it, report it to your county Extension educator. Then if it's an isolated plant or two, pull it and burn it. Or take your chances, but know that taking your changes means 500,000 to one million weed seeds per plant will be produced. They're light and scatter easily.