The plant was found in a field during a corn harvest in Stephenson County. It’s native to eastern Asia; the first U.S. detection was in 1990 in New York.
It spreads rapidly through seeds, which can move through landscapes via waterways. The University of Illinois Extension says there have been reports of herbicide resistance in its native ranges. It’s concerned the species could develop a similar resistance in the U.S.
Illinois is the third state with an Asian copperleaf presence. It’s already been found in 10 counties in central and western Iowa.
Identifying the plant without its reproductive structures is difficult, but the Extension says it’s easiest to identify the weed between harvest and frost or tilling. It suggests scouting for the plant during the growing season.
The University of Illinois Extension suggests harvesting fields that have Asian copperleaf last. That way, it’s less likely for seeds to move to other fields on harvesting equipment. Seeds can also be spread through livestock manure, so Extension suggests being cautious about grazing livestock in fields that could containAsian copperleaf.
If you think you may have found Asian copperleaf in your corn or soybean fields, University of Illinois Extension can help to confirm its identification.
Check out the U of I factsheet for more information.
