Resistance of wild carrot (Daucus carota) to 2,4-D in Michigan

Differential response of wild carrot to 2,4-D was found in seeds collected from 10 locations in Michigan, three in Ohio, one in Illinois, and one in O ntario, Canada. Greenhouse studies were conducted on plants grown from the collected seeds to confirm resistance of wild carrot to 2,4-D, and to study variations among and within populations. The differential response of wild carrot to 2,4-D in field research was due to resistant individuals. Among the 14 locations, wild carrot control with 2,4-D ranged from 18 to 91%. Wil d carrot varied in its response to 2,4-D among and within populations as we ll as within individual umbels. In 69% of the tested samples, at least one wild carrot plant was resistant to 2,4-D.