Weeds are a problem for many of us. Whether they’re in your garden, your row crop fields or your pastures, they’re unwanted plants that can sometimes be next to impossible to eradicate. The main reason for controlling weeds is the fact that they can reduce the quantity and quality of the desired forage species in your pasture. In the state of Missouri, there are several classifications for weeds. The weeds are classified depending on the difficulty to rid the land of the weed, or other various factors. One such classification is of noxious weeds.
According to the University of Missouri Extension website, “Noxious weeds are those for which control measures, to some extent, are required by law. Across the United States, more than 500 weeds have been designated as noxious by either weed or seed laws. In Missouri, 11 weeds carry that designation.” Up until December 19, 2007, there were only 11 weeds on this list which included Canada thistle, field bindweed, johnsongrass, kudzu, multiflora rose, purple loosestrife, common and cutleaf teasel, musk thistle, Scotch thistle and marijuana. After the 94th General Assembly of the Missouri House of Representatives passed House Bill (HB) 1483 on December 19, however, two new weeds were added to the noxious weed list, bringing the number up to 13.  
With the passing of HB1483, spotted knapweed (cetaurea biebersteinii, including all subspecies) and sericea lespedeza (lespedeza cuneata) were “hereby designated as noxious and dangerous weeds to agriculture.”
According to Doug Bowerman, a Lawrence County Assessor, the key is to be able to identify spotted knapweed. Seedlings emerging in the fall often overwinter as a rosette of leaves resuming growth in the spring. The plant grows two to four feet tall and bears alternate, pale green leaves which are one to three inches long. Leaf margins of the lower leaves are divided and smooth while the surface of the leaf is rough. Stems are erect and rough, with slender branches. Numerous flowers are produced during the summer months and are pink to purple in color.
Sericea lespedeza is a shrubby, deciduous perennial that can grow to be two to five feet tall. Coarse stems are single or clustered with numerous branches. Stems and branches are densely leaved. Leaves are trifoliate, which means they come in pairs of three, and are club or wedge-shaped (wider at the tip than at the base). They’re 1/4 to one inch long. The leaf is round to flat at the top, with an obvious point at the tip. The lower leaf surface has silky hairs.
Tom Hansen, an agronomy specialist said, “it isn’t difficult to control spotted knapweed if you’re watching for it.” He added that you need to be able to identify and control the plant during the rosette stage in order to successfully contain and eradicate the now-noxious weed. Milestone or Tordon 22K are the best to kill off spotted knapweed and it should be treated before it reaches 12 inches tall.  Sericea lespedeza should be treated with Pasturegard, Cimarron or Remedy. Opposite of the knapweed, you should apply these pesticides after sericea lespedeza has reached 12 inches in height.
It’s important to keep up with the changes in weed classifications to ensure that your farming operation is safe from fees and fines, and it will help keep you from contributing to the rising weed problem in Missouri.
Don Ruzicka, State Representative for the 132 District warned, “It is a class A misdemeanor to violate noxious weed laws in Missouri.” According to an agricultural law publication for Missouri put out by the National Association of State Departments of Agriculture Research Foundation, “Landowners are required to control noxious weeds on their properties. Depending on the particular noxious weed involved, a landowner may be fined for failing to control the noxious weed.” There is a significant fine for failing to control noxious weeds, and the fine varies from weed to weed.


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