Other common names
Purple mustard, tenella mustard, bead-podded mustard, musk mustard
Scientific name
Chorispora tenella
Family
Brassicaceae
Description
A leafy, branching plant growing up to 1 1/2 feet tall, blue mustard sprouts in the fall, growing a ground-hugging rosette form. It matures early in the spring, often before homeowners are aware it is present. Blue mustard is characterized by a strong, unpleasant odor. It is commonly found growing in groups rather than as single plants.
Typical plants growing in a disturbed site. Photo by W. Hanson Mazet.
Leaves
Alternately attached leaves are somewhat spear-shaped to oval, somewhat toothed, and are covered with tiny. sticky hairs.
The leaves are somewhat spear-shaped and have wavy, toothed margins. Photo by W. Hanson Mazet.
Stems
Branch mostly from the base; sticky to the touch.
Flowers
Small, purplish flowers are about 1/2-inch across, with four petals in a cross shape. Blooms during the early spring. Seeds are produced in long narrow pods.
The purplish flowers occur in clusters at the ends of stems. Photo by W. Hanson Mazet.
Roots
Grows a shallow taproot.
The rosette leaves are somewhat lobed. Photo by J. DiTomaso, UC Davis.
Native to
Europe
Where it grows
Roadsides, vacant lots and dry, disturbed sites
Life cycle
Winter annual (sprouts in fall and flowers in spring)
Reproduction
Reproduces by seed; seed can be produced within 10 days of flowering.
Control methods
As with all annuals, preventing seed production is essential. Control before seeds are produced in the early spring.
Mechanical
Cultivation is very effective in controlling this plant. Dig, hoe or pull young plants. Mowing during early flowering reduces seed production.
Cultural
Plant desirable vegetation to help suppress it. Thick mulches may be effective in reducing infestations.
Biological
None commercially available.
Chemical
Try broadleaf selective herbicides such as 2,4-D + dicamba on rosettes early in the spring. Dicamba can persist for several months and may damage desirable plants in the area treated. Glyphosate can also be used on rosette leaves but is nonselective and damages both grasses and broadleaf plants. Add a surfactant per label instructions to enhance uptake by the waxy leaves. Pre-emergence herbicides will help to manage existing seed banks.
References
Butler, M.D. 1994. Blue mustard. Pacific Northwest Extension Publication 471, PDF.
CA Dept. of Food and Agriculture. No date. Blue or purple mustard, CDFA.
DiTomaso, J.M. and E.A. Healy. 2007. Weeds of California and Other Western States. University of California Publication 3488.
Lyon, D.J., R.N. Klein and R.G. Wilson. 2006. Blue mustard control. NebGuide G1272, image.
USDA-NRCS Plants Database. 2011. PLANTS profile for Chorispora tenella, USDA.
Whitson, Tom D. (editor). 2002. Weeds of the West. University of Wyoming, Jackson, Wyoming.
