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Noxious & Invasive Weed Species to be Controlled |
Listed below are weed species descriptions, distribution, problems, and possible management methods for weeds considered noxious by the State of Iowa and Johnson County. This web page is meant to give general knowledge of these problem weeds, why they are a problem, and common methods of control. Individual weed and management circumstances may vary and these recommendations should be used as changing situations dictate.
The Iowa Department of Agriculture and Land Stewardship and the Code of Iowa have declared 27 species of plants as noxious weeds which need to be controlled. The State of Iowa has declared the following weeds noxious:
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In addition to the State of Iowa Noxious Weed List, Johnson County lists an additional four species of noxious weeds. These species are:
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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.
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This web page also contains very general herbicide control methods. This web page is not intended to promote the sole use of herbicides, rather using herbicides as a tool and as an overall part of an integrated weed management program. Changes in pesticide regulations occur constantly. If you have questions about the usage or legality of certain herbicides, contact your County Extension office, or the Iowa Dept. of Agriculture & Land Stewardship. Always read and understand chemical labels before use. The recommendations for using herbicides included in this web site are incomplete and should not serve as a substitute for herbicide labels. Complete instructions for the use of a specific herbicide are on the herbicide label. The pesticide user is responsible for applying pesticides according to label directions, as well as for problems that may arise through misapplication or misuse of the pesticide. Label changes, product cancellations, and changes in recommendations may have occurred since the production of this web site. Before using herbicides, consider whether possible impacts of chemicals outweigh the benefits of other management techniques, whether there are other appropriate management choices, and also whether the area is appropriate to use herbicides. For more specific information on plant identification or management, consult with knowledgeable professionals before attempting control. Some weed species are nearly impossible to manage without the careful use of some herbicides. The best weed control program begins with prevention. Once weeds are established though, using several management methods in an integrated weed control program will generally give the best results.
A variety of methods are used to control invasive and noxious plants. Their effectiveness will vary with the type of infestation, weed species, and the skill and dedication of the persons controlling weeds. Select a control method, which meets the goals of the particular area (i.e. lawn, prairie, agricultural field, etc.) where weeds have invaded. The majority of these management methods are most effective when used in combination as part of an integrated vegetation management program. For example, much better control of canada thistle (Cirsium arvense) can be achieved using mowing, competitive seeding, herbicide applications, and prescribed burning all as management tools, rather than relying solely on just one method.
Identifying noxious weeds correctly and preventing them from establishing is a much more efficient and effective management strategy than is waiting for a weed to reach epidemic levels. With some weed species, such as canada thistle, japanese knotweed, or purple loosestrife, this may be the only real opportunity to "control" the weed. Some noxious weeds are extremely difficult to get rid of once they are established, and long-term management is necessary just to reduce their populations to acceptable levels. Noxious weed management is expensive in terms of dollars, but also in time spent and energy used.
| Don’t know what a word means? |
Try looking in the glossary of plant terms for help. Here you can find various explanations of terms such as "annual", or "rosette" to assist in correctly identifying characteristics of some of the noxious or invasive weeds of Johnson County.
| Where can I find references on weeds? |
A list of text references is available to help find materials on weeds and weed control. Local libraries, extension offices, etc. often have various information on native plants, noxious and poisonous plants, and alternative plants which can be used in landscaping or around the home. Use these materials to learn more about the native and introduced plants in Johnson County.
