Invasive Weed Species Which Merit Management Consideration: New exotic weed pests are continually being discovered encroaching into the State of Iowa. Many of these weed species can be controlled early in the discovery phase, and before infestation. The IRVM Program and the County Weed Commissioner, while focusing on noxious weeds, also evaluates the spread and the environmental impacts of new weeds on Johnson County. If a weed species is considered to have a significant detrimental impact on the resources of Johnson County, the Weed Commissioner can seek to have that species declared noxious by the Board of Supervisors. That weed species can then be included as part of the overall weed management plan.

This is a list of plant species which are considered invasive or aggressive by the Johnson County IRVM Program and County Weed Commissioner. These species are unsuitable for use or growth in roadside plant communities. Because of concern for their spread into public right of ways, planting these species in adjacent private lands is discouraged. This plant species list is not all-inclusive, and may be edited to include or remove certain species as conditions or situations dictate.

Autumn Olive (Elaeagnus umbellata)
Black Locust (Robina pseudoacacia)
Bush Honeysuckle (Lonicera spp)
Canada Thistle (Cirsium arvense)
Chinese Bush Clover (Sericea lespedeza)
Common and Glossy Buckthorn (Rhamnus cathartica & Rhamnus frangula)
Common Reed Grass (Phragmites australis)
Common Teasel (Dipsacus fullonum)
Crown Vetch (Coronilla Varia)
Garlic Mustard (Alliaria petiolata)
Japanese Barberry (Berberis thunbergii)
Japanese Knotweed (Polygonum cuspidatum)
Leafy Spurge (Euphorbia esula)
Mulitflora Rose (Rosa multiflor)
Oriental Bittersweet (Celastrus orbiculatus)
Purple Loosestrife (Lythrum salicaria)
Reed Canary Grass (Phalaris arundinacea)
Smooth Brome (Bromus inermis)
Plumeless and Musk Thistle (Carduus acanthoides, Carduus nutans)
Tree of Heaven (Ailanthus altissima)
Wild Parsnip (Pastinaca sativa)
Yellow and White Sweet Clover (Melilotus officinalis and Melilotus alba)