Tough Weed Spreading In Iowa

Palmer Amaranth is a pigweed native to the Southwest U.S., over the last couple decades it has moved eastward, and in the last seven years it's moved into the corn belt.

Now Palmer Amaranth is in Iowa.
ISU weed specialist Dr. Bob Hartzler says Palmer Amaranth infestations are all isolated incidents in around 15 border counties, but farmers should be on the lookout.

Palmer Amaranth looks a lot like water hemp, which is found in a lot of Iowa fields; however, it is much more competitive and resistant to chemicals.

Hartzler says, "The one trait that's really reliable in differentiating Palmer Amaranth and water hemp is the female plants on these inflorescence is they have sharp bracts along the flowers so it gives the seed head a very spiky appearance. And when it's mature, when you grab them like this, those bracts will actually puncture your skin."
Hartzler says Palmer Amaranth has been found as a contaminate in conservation planting seed mixes and suggests farmers should be scouting those fields.
He says because the infestation is still in the early stages, the density is low enough that the weed can be eradicated with effort.
In a word of warning, he adds the south did not manage to stop the infestation and that devastated cotton production, "In cotton they have far fewer herbicides available than we have in corn or soybeans and the farmers were completely reliant on glyphosate in round up ready cotton. And when they developed the glyphosate resistance Palmer Amaranth, they didn't respond quickly enough and they tried to rely on the glyphosate when it no longer controlled."