URBANA, Ill. — Farmers are turning to an old technology this year to control weeds in their fields. Todd Gleason has more on what they can expect from a new, old-product.
Dicamba has been around for about half-a-century. It is a corn herbicide, but soybeans have been modified to tolerate it. This was done because so many weeds have modified themselves to resist being killed by glyphosate, commonly known as Round-Up. The primary problem, says University of Illinois Extension Weed Scientist Aaron Hager, is waterhemp.
Hager: Dicamba, in the 50 years that we’ve used it, has never been excellent on any of the pigweed species. It can be good. It can be very good, but it is not excellent. It is not as consistent.
This inconsistency makes the timing of dicamba applications extremely important. Without a doubt, says Hager, most post applied herbicides are going to do a better job of controlling a full suite of weeds in a field when the weeds are less than three to four inches in size.
Hager: Certainly, with something like dicamba and waterhemp, our recommendation to farmers is to treat very, very small weeds, but to go back in about 10 to 14 days and to scout those treated fields. Look to see what the efficacy has been. Sometimes we can twist up these pigweed plants, but that doesn’t mean they will necessarily be completely controlled.
It is possible for the weeds to recover, flower, and produce seed. And that, says Aaron Hager, is something to avoid.
— Aaron Hager, Extension Weed Scientist – University of Illinois
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