Blue mustard is a non-native winter annual that germinates in late fall or early winter. It overwinters in a rosette and resumes active growth in the spring. Mature seed is produced by early summer. Blue mustard has bluish-purple flowers that produce small bean-like seed pods. Reducing the production of seeds is effective as a control.
Annual mustards, such as blue mustard, tend to grow in poor soils. Their presence in an area may indicate that the current plant community is in poor condition. These areas should be augmented with grass seeding or other plants to compete with the blue mustard.
The best time to control blue mustard with herbicides, such as 2,4-D is in late winter to early spring, when growth resumes. Control methods should be used before mid-April at the very latest.
For more information, see the following Colorado State University Extension fact sheet(s).
For more information, see the following Planttalk Colorado™ script(s).