ROCKFORD, Ill. (AP) — Crop-menacing super weeds have developed resistance to commonly used herbicides, and experts are urging Illinois farmers to be vigilant as the tenacious plants move northward across the state.
A dozen weed types have become resistant to glyphosate, an active ingredient in commonly used farm and garden herbicides, The Rockford Register Star reported (http://bit.ly/1eBJium ) over the weekend.
The weeds, which the herbicides used to be able to single out and kill, have evolved to imitate the crops around them and have become increasingly difficult to eliminate.
Two species from the pigweed family, Palmer amaranth and common waterhemp, are particularly worrisome to corn and soybean farmers. Some can grow to be seven feet tall and produce 1 million seeds.
"It certainly has been a hot topic this winter," said Russ Higgins, a University of Illinois crop scientist. "The big news in 2014 is going to be Palmer and trying to control it."
The weeds were once more prevalent in southern portions of Illinois but are on the move.
The Palmer amaranth, which is indigenous to dry regions in the Southwest, has now been documented in northern Illinois' Grundy County and can lead to huge corn and soybean losses.
A key strategy is for farmers to fight the weeds before they have a chance to establish themselves firmly in a field over several years, said Higgins.
There is also a heightened concern among farmers about waterhemp.
In 2013, the University of Illinois offered to test waterhemp in the area for glyphosate-resistance, and its laboratory expected 400 samples — but it received more than 1,000.
Information from: Rockford Register Star, http://www.rrstar.com