Return to: U of M Home
Information pieces on noxious weeds face stiff competition for the public's attention from the many catalogs and nurseries featuring brightly colored annuals and tempting perennials. While some noxious weeds are actually attractive, they just don't have the appeal of a lovely begonia or unusual hosta.
Here in Washington County, with many acres devoted to homes on large lots, it's important for residents to know that Minnesota prohibits 11 noxious weeds that by law must be controlled on all public and private lands. Hobby or larger acreage farmers may already be aware that noxious weeds are poisonous and can injure animals and people.
How does a weed get on Minnesota's noxious weed list? Noxious weeds are defined as difficult to control or injurious to public health, the environment, roads, crops, livestock, and property. The list is made up of one annual, four biennials, and six perennial weeds. Annual weeds complete their life cycle in one growing season, while biennials require two growing seasons. Biennials form a rosette (cluster of leaves close to the ground) the first year and in the second year they develop a flower stalk, flower, produce seed, and then the plant dies. A perennial weed lives three or more years.
Hemp is an annual that can be found throughout the state. The four biennials are garlic mustard, bull thistle, musk (nodding) thistle, and plumeless thistle. The six perennials are Canada thistle, field bindweed, leafy spurge, perennial sowthistle, poison ivy, and purple loosestrife.
Landowners should become familiar with the appearance, behavior, and control methods of noxious weeds and take action when they are discovered. Noxious weeds can move in fast when soil is disturbed by development so it's important that landowners quickly plant non-invasive plants to stave off noxious weeds. Washington County and its communities have weed inspectors and residents can be fined if noxious weeds aren't controlled. -Alice Pepin, Master Gardener
For a color fact sheet on Minnesota's noxious weeds, visit the University of Minnesota Horse Web site.
Invasive Terrestrial Plants (MN DNR Website)
Minnesota Noxious Weed Program (MDA Website)