A weed first discovered in Black Hawk County, Iowa, in 2016 has again been spotted in 2022, nearly 30 miles away in Grundy County. Due to its potential threat to row crops, the Iowa Department of Agriculture and Land Stewardship is asking Iowans to report any sightings to determine the potential scale of the infestation.

Asian copperleaf, or Acalypha australis, is native to China, Australia, Japan and other countries on the Pacific Ocean, and was first discovered in Iowa in a corn field near Cedar Falls. Prior to this discovery in 2016, the only documented infestation in North America was within New York City. The plant was recently found in a soybean field in Grundy County, nearly 30 miles from the original infestation. In both fields, several dense patches of the weed were present throughout the field, indicating the weed was in the field for several years before being identified. It is unknown how the plant was introduced to Iowa, but it is likely the two reported infestations are related. The plant is a threat to row crops in its native range.

Identification

Asian copperleaf is in the spurge family but lacks the milky sap common in many spurges. It is an erect plant that can reach heights of 2 to 3 feet, but most plants found in Iowa were less than 18 inches tall. Leaves are 2 to 3 inches long, lanceolate with serrated, finely toothed edges. The distinguishing characteristic of Asian copperleaf are the bracts located beneath the flowers. The bracts are circular to heart-shaped, with a dentate margin. Virginia copperleaf and three-seeded mercury, two other Acalypha species present in Iowa with a similar growth habit, have deeply lobed bracts. It is unlikely anyone could confidently differentiate among these species prior to flowering. Asian copperleaf seems to emerge late in the season and remains under the crop canopy throughout the growing season.

Requested action

The Iowa Department of Agriculture and Land Stewardship and Iowa State University are interested in determining how widespread the weed is across the state. By determining how much area is infested with this weed, a better estimate of the risk it poses to Iowa crop production can be made. Asian copperleaf was detected in both fields during crop harvest. Thus, the Iowa Department of Agriculture and Land Stewardship is requesting that farmers and others in the agricultural industry keep an eye out for this plant as fields are harvested.

If you detect the plant, please contact the Iowa Department of Agriculture and Land Stewardship at 515-725-1470 or email [email protected].

Source: Iowa Department of Agriculture and Land Stewardship