Issue 6, July 8, 2022

Illinois Laws Regulating Noxious, Exotic Weeds

The State of Illinois has two “legal” lists of problematic plants that require attention – Noxious Weeds and Exotic Weeds.

The Illinois Noxious Weed Law, set into Illinois Administrative Code, lists 9 weed species that must be controlled on property owned or managed.  These weeds have detrimental effects on public health, agricultural crop production, or animal production.  They must be controlled so they don’t produce seeds or any other means for propagating, or totally eradicated using legal means.  This law is under the direction of the Director of the Illinois Department of Agriculture.  Most counties in Illinois have a designated Weed Control Superintendent (Weed Commissioner) for local control authority.  Enforcement can result in a fine.  The reality is however, that this law tends to be complaint driven and sadly is often poorly enforced due to a lack of funding and personnel.  Some counties are stricter than others.  This list has primarily remained the same since its creation in the 1970’s with only one addition of Kudzu in 2002.

    Weeds on this list include:
  • Common ragweed (Ambrosia artemisiifolia)
  • Giant ragweed (Ambrosia trifida)
  • Marijuana (Cannabis sativa) (outdoor grown)
  • Musk thistle (Carduus nutans)
  • Canada thistle (Cirsium arvense)
  • Kudzu (Pueraria montana var. lobata)
  • Perennial sowthistle (Sonchus arvensis)
  • Johnsongrass (Sorghum halepense)
  • Sorghum almum (Sorghum almum)

Please note that the two ragweed species need only to be controlled within the corporate limits of cities, towns and municipalities.  All other weeds on the list must be controlled anywhere in Illinois. The local weed commissioner can also declare certain weeds as noxious in the county under his or her jurisdiction.  More information on the Illinois Noxious Weed Law can be found here.

The Illinois Exotic Weed Act, also set into Illinois Administrative Code, is managed by the Illinois Department of Natural Resources (IDNR).  These non‐native plants, when planted, will spread by seeds or vegetative propagules (rhizomes, bulbs, tubers, corms, etc.) and naturalize, degrading natural communities, reducing the value of fish or wildlife habitat, and threatening Illinois endangered or threatened species.  For most of these plants, it’s the seeds that have caused these plants to spread, particularly in forested and wooded areas.

This law doesn’t require the owner or manager of the property to control these plants like the Illinois Noxious Weed Law does. Rather, the intent is to prevent the spread. The Act does state you cannot sell or plant these without a permit from IDNR. Please do what you can to prevent these species from spreading, including removing flowers before they set seed. For example, timely mowing can help prevent the spread of Teasel and Poison Hemlock along roadsides. Keep in mind that controlling these species is the ultimate form of preventing the spread of these invasive species.  Again, this law does not require control.        

The following species are on the list. Additionally, and this is crucial, ALL their cultivars are included, no matter who or what says the cultivars are sterile.  Any cultivar of these plants CANNOT be legally sold or planted in Illinois without a permit from IDNR.  This includes all the so‐called sterile purple loosestrife cultivars as well as the Fine‐Line® buckthorns.

Included plants are:
Giant hogweed (Heracleum mantegazzianum)*
Poison hemlock (Conium maculatum)*
Teasel (Dipsacus spp.)*
Exotic buckthorns

  • Chinese buckthorn (Rhamnus utilis)
  • Common buckthorn (Rhamnus cathartica)
  • Dahurian buckthorn (Rhamnus davurica)
  • Glossy buckthorn (Rhamnus frangula)
  • Japanese buckthorn (Rhamnus japonica)
  • Saw-toothed buckthorn (Rhamnus arguta)

Exotic olives

  • Autumn-olive (Elaeagnus umbellata)*
  • Russian-olive (Elaeagnus angustifolia)*
  • Thorny-olive (Elaeagnus pungens)*

Invasive/exotic bush honeysuckles

  • Amur honeysuckle (Lonicera maackii)*
  • Morrow’s honeysuckle (Lonicera morrowii)*
  • Sweet breath of spring (Lonicera fragrantissima)*
  • Tartarian honeysuckle (Lonicera tatarica)*

Invasive knotweeds

  • Bohemian knotweed (Fallopia x bohemica)*
  • Giant knotweed (Fallopia sachalinensis)*
  • Japanese knotweed (Fallopia japonica, syn. Polygonum cuspidatum)*


  • Japanese honeysuckle (Lonicera japonica)
  • Kudzu (Pueraria montana var. lobata)
  • Lesser celandine (Ficaria verna)*
  • Multiflora rose (Rosa multiflora)
  • Oriental bittersweet (Celastrus orbiculatus)*
  • Purple loosestrife (Lythrum salicaria)
  • Salt cedar (Tamarix spp.)

This species list was last added to in January 2016. Kudzu is the only plant also on the Noxious Weed list.
More information can be found here.  

Michelle Wiesbrook, adapted from an article written by David Robson, University of Illinois

Michelle Wiesbrook

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