Photo by Pamela Smith

Populations of waterhemp are continuously becoming more resistant to herbicide 2,4-D, according to Iowa State University’s Integrated Crop Management News. Iowa State Extension Field Agronomist Meaghan Anderson reports that Corteva discovered 2,4-D-resistant waterhemp in Wright County in north-central Iowa. Two samples were collected, one from a plant in the field and the other from a plant growing in the ditch next to the field.

While the complete cropping history of the field is unknown, Anderson says both the field and the ditch had repeated exposure to 2,4-D and Enlist soybeans were planted in the field. The plant populations are now being tested by Corteva for further evaluation. If resistance is confirmed, Iowa will be the fourth state where 2,4-D-resistant waterhemp has been found. The other states include Nebraska, Illinois and Missouri.

Read more on herbicide-resistant weeds here.