Department of Plant, Soil and Microbial Sciences Weeds

Wild mustard (Brassica kaber (D.C.) L.C. Wheeler)

Life Cycle:

Winter/summer annual. Emerges in late summer, early fall or spring. In Michigan, several populations of wild mustard act as a summer annual. Flowering peaks in June and July, but can continue until the first frost.

Emergence:
Emerges from soil depths of 1-inch or less.

Seed:

Production Range: Approximately 1,200 seeds per plant.

Dispersal Mechanisms: Seed pod dehiscence (splitting open).

Longevity: Low persistence - 50% of the seed bank is reduced in less than one year, and it takes seven years to reduce the seed bank 99%.

Dormancy: Initially dormant. Dormancy is broken by a combination of changes in temperature, light, and nitrate levels.

Competitiveness:

One of the more competitive weeds with small grains, soybean, and corn. Winter cereal yields were reduced 13 to 69%, when the biomass was comprised of 1 to 60% wild mustard. Soybean yields were reduced 46% with 4 plants per yard of row and corn yields were reduced 1.5- to 2-fold and 5- to 6-fold at low and high wild mustard densities, respectively.

Preferred Soil/Field Conditions:

Grows on a wide range of soils.

Management:

Biological

Predation/grazing: Ground beetles (carabids) eat wild mustard seed lying on the soil surface.

Decay: No information.

Mechanical

Tillage: Seedlings are readily killed by tillage.

Rotary Hoeing: Hoe before weeds exceed 1/4-inch in height, once established wild mustard is difficult to control.

Flaming: Effective on small wild mustard.

Cultural

Crop rotation: Corn-soybean rotations will deplete wild mustard populations more rapidly than continuous wheat.

Planting date: Later planting will reduce wild mustard populations.

Chemical

Application timing and effectiveness: Several herbicides are effective for controlling wild mustard. Control is greater when herbicides are applied to smaller wild mustard plants. Please refer to E-434, "MSU Weed Control Guide for Field Crops," for herbicide recommendations.

Additional Information

Wild mustard can serve as an alternate host of nematodes and many insect pests.