Invasive Asian Copperleaf Found in Minnesota

The invasive weed was identified in a Rice County corn field in fall 2025 by University of Minnesota Extension experts.

Updated on Oct. 14, 2026 in Botany

Invasive Asian Copperleaf Found in Minnesota

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University of Minnesota Extension scientists confirmed the discovery of invasive Asian copperleaf in a Rice County corn field during the fall of 2025. The plant, which reproduces strictly by seed, was identified by examining specific floral bracts.

Why it matters

The discovery marks the arrival of a high-risk species previously identified in other states that can threaten crop productivity. Because the weed spreads through equipment and soil, experts are urging farmers to scout their fields carefully during harvest.

Asian copperleaf typically grows to 18 inches under a crop canopy and reaches up to 3 feet in full sun. The species was first documented in the United States in New York in 1990 and was later categorized as a high-risk species in a 2012 USDA assessment.

The players

University of Minnesota Extension

This organization provides outreach and research-based knowledge to citizens and farmers throughout Minnesota.

United States Department of Agriculture

The federal executive department responsible for developing and executing laws related to farming, forestry, and food.

The details

The plant spreads primarily through the movement of soil, equipment, and crop residue across fields. Extension scientists confirmed the discovery by analyzing the plant's floral bracts, and they are now moving to test the local population for potential herbicide resistance.

1990: Asian copperleaf was first identified in the United States.
2012: The USDA released a high-risk species assessment for the weed.
2016: The species was found in an Iowa corn field near Cedar Falls.
Fall 2025: Asian copperleaf was identified in Rice County, Minnesota.

The Big Picture

The identification of this species in Minnesota aligns with trends noted in the 2012 USDA Asian copperleaf high-risk species assessment. This finding forces a reevaluation of current regional weed management protocols as the plant continues to move westward across the Corn Belt.

Farmers in the area are advised to watch for the weed while harvesting, as the plant can contribute to significant crop yield losses. Scouting now can prevent the further spread of the species through equipment and soil movement.

The takeaway

Farmers should clean equipment thoroughly between fields to prevent the unintentional spread of invasive seeds. Regular monitoring remains the most effective tool for managing high-risk weeds that have not yet established widespread populations.