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Back To: Hardin County | Your Government | Roadside Vegetation | Invasive and Noxious Weeds

Invasive and Noxious Weeds

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Invasive and Noxious Weeds
Department Roadside Vegetation
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Noxious weeds are weeds that, required by law, must be controlled. In Iowa, they consist primarily of invasive weeds, but do include two native species that can be troublesome in agricultural settings. Not all invasive weeds are declared noxious. 

Iowa Noxious Weed List & Laws

All landowners are required to control those weeds on their property that have been declared noxious by the State of Iowa or by Hardin County.

Canada Thistle

What Makes a Weed Noxious?

What makes a plant noxious in the context of Hardin County’s natural resources, is its negative impact on agriculture, or its ability to spread and crowd out native plants. Therefore, noxious weeds are distinguished from those weeds that occur in small numbers and are innocuous.

Noxious weeds are those able to reproduce in the wild, spread rapidly, which are difficult to control, or which cause the decline or loss of our native plants.

It is not completely understood why some weeds become noxious and some don’t. But because noxious weeds did not evolve locally, their populations are not held in check by natural predators or diseases, giving them a competitive edge over native plants. Noxious weed species can proliferate and spread over large areas. Some can completely displace other vegetation, forming a homogeneous (single species) cover. Contrast this situation with the rich variety and diversity of a native plant community such as is seen in prairies, wetlands, or forests.

Coming to Hardin County

Noxious weeds are exotic plants that have reached Hardin County and Iowa by escaping from gardens, being transported by hay or straw, air, dirt, tires, clothing, etc. They grow aggressively, lack natural enemies, and resist management methods. These species can move quickly into bare areas which have been disturbed by construction or erosion, have poor vegetative cover, or have other soil disturbances. Some of Iowa’s noxious weeds are spread by windblown seed, birds, or other organisms. Other weeds spread though poorly timed mowing or baling of hay to be fed to livestock or sold. And other noxious weeds spread by sending rhizomes (long underground roots) to uninfested areas.

Controlling Noxious Weeds

Most of Iowa’s noxious weeds can be easily controlled through proper management. Techniques to combat weeds include:

  • mowing
  • cutting
  • burning
  • competitive seeding
  • cultivation
  • herbicide usage

A primary key to weed control is early detection and management, before that weed has spread and built up a large seed bank and energy reserve.

Japanese Knotweed


Who controls noxious weeds in Hardin County?

All landowners are required to control noxious weeds on their property to eliminate seed production. Weeds growing within city limits, in abandoned cemeteries, along railroads, streets, and highways, as well as on farmland, or any private or public land, must be controlled. The Hardin County Weed Commissioner enforces the Iowa Noxious Weed Law. Iowa Code Chapter 317 – Weeds

How do I contact the County Weed Commissioner?

Every county in Iowa has a Weed Commissioner to oversee that county’s noxious weed control program. The Hardin County Weed Commissioner is located at the Engineers Office 708 16th St., Eldora, IA 50627 Phone: 641-939-8263

Why should I control noxious weeds?

Noxious Weeds and other invasive species threaten all of our natural resources. They can destroy native plant and animal habitat, damage recreational areas, clog waterways, lower land values, decrease agricultural crop yields, and some can even poison humans and livestock.

Noxious Weeds are also a leading cause of species endangerment under the Endangered Species Act. The Iowa Department of Agriculture and Land Stewardship, along with Hardin County, has declared 31 species of plants as Noxious.

View a complete list of plants considered noxious by Hardin County or the State of Iowa. Complete list of noxious plants.

Contact Us

Roadside Vegetation Office

Physical Address

708 16th St.
Eldora, IA 50627

Mailing Address

1215 Edgington Ave Suite 1
Eldora, IA 50627

Phone: 641-858-5058

Fax: 641-858-3182


Monday - Friday
07:00 AM - 03:00 PM