Source: University of Missouri

If you've had problems with musk thistle on your land in the last year and intend to apply chemical control, early spring is a good time to check for new growth of this noxious weed, said a University of Missouri Extension agronomy specialist.

"For optimal control, herbicides should be applied when musk thistle is in the rosette stage, typically in the fall or early spring," said Travis Harper. "Landowners should walk fields in the spring or fall looking for these rosettes." The musk thistle rosette is a flat circle of leaves that can reach a diameter of 2 feet or more.

Timing is critical. "Spraying after the plant has bolted and/or produced a flower is too late to achieve good control," Harper said. "Typically, the plant will survive, flower and produce viable seed."

Spray rosettes with 2,4-D or other registered herbicide, he said. Musk thistle, a European weed introduced to the U.S. in the 1800s, can infest old fields and overgrazed pasture. 

Original news release