“Noxious” Weeds in Wisconsin

“Noxious” Weeds in Wisconsin
Jerry Doll

Some feel that any weed is noxious. Webster tells us that noxious means harmful so in a general sense, all weeds are noxious. However, the state legislature has declared only three perennial weeds as legally noxious in Wisconsin. These are Canada thistle, field bindweed and leafy spurge. The law is open ended in that any other species can be declared noxious:

“…as the governing body of any municipality or the county board of any county by ordinance or resolution declares to be noxious within its respective boundaries.”

It appears that we have not had a very conscientious nor consistent application of the law. The law states that:

“the chairman of each town, the president of each village, and the mayor of each city, shall appoint one or more commissioners of noxious weeds…”

Seldom is this done. Nor is the law written in a way that makes it practical to comply in that it states:

“Every person shall destroy all noxious weeds on all lands which he shall own, occupy or control. The term ‘destroy’ means the complete killing of weeds or the killing of weed plants above the surface of the ground by the use of chemicals, cutting, tillage, cropping system, pasturing livestock, or any or all of these in effective combination, at such time and in such manner as will effectually prevent such plants from maturing to the bloom or flower stage.”

The fact that we have not eradicated the three “official” noxious weeds by passing the noxious weed law is not surprising, nor does it mean that the law has been totally ineffective. Even though few have been billed for not controlling these species, the law has served to highlight their aggressive nature of growth and difficulty of control. And hopefully it has also served to alert those who do not have these weeds, or who only have small areas infested, to take appropriate action to prevent them from becoming more wide spread.

More Weed Laws

A lesser known law that includes regulations on weeds is the “Wisconsin Feed Law”. Some feeds contain corn or soybean screenings which are composed of cracked or immature grains, plus weeds seeds. The feed law allows weeds to be in commercial feed but established certain regulations that must be followed. For example, the 1980 edition of the law states:

 the feed label shall “clearly and permanently” indicate if more than 0.01% of viable noxious weed seed or more than 0.25% of other viable weed seeds (except wild buckwheat) is in the feed

 noxious weeds as defined by the feed law are:

Canada thistle
wild mustard

Another dimension from which noxious weeds have been legally defined is that of the Wisconsin Crop Improvement Association. The 1990 edition of the Wisconsin Seed Certification Standards states that;

“Prohibited noxious weed seeds include the seeds of Canada thistle, field bindweed, leafy spurge and quackgrass”.

These are the same species as found in the noxious weed law with the addition of quackgrass and this list applies to all certified crop seeds. In addition, many the Certification Standards define additional prohibited or restricted weeds for each crop seed or crop seed group. The restricted weeds can be present in very small quantities in certified seed and are defined for each crop or crop group. For example, the prohibited weed seeds in small grains (in addition to those mentioned) are Indian mustard, wild mustard, wild oats, wild proso millet, wild radish, woolly cupgrass and yellow rocket. The restricted weed seeds in small grains are buckhorn, dodder, downy brome, giant foxtail, hoary alyssum, oxeye daisy, perennial sowthistle and white cockle.

We see that these lists of noxious weeds do not agree. This is not surprising nor inappropriate. Hopefully they all serve to alert suppliers and buyers alike of the species to be aware of that present special problems in their fields, feed or seed.

And lastly we have the “nuisance weeds” law. This includes “any non-native member of the genus Lythrum (purple loosestrife) or hybrids thereof and multiflora rose”. This law prohibits selling, distributing, or planting nuisance plants or seeds of these species in Wisconsin.

See also: Weed Laws in the Wisconsin State Statutes

October 1990