Invasive Weeds – Why Should We Worry?
Should we worry whether the plants growing around us are native to our area or not? Isn’t it all just "nature?" Before you dismiss this issue as unimportant, consider the following:
- Invasive weeds in agricultural and natural areas cost our country $13 Billion dollars per year
- Invasive weeds are the second most important reason for the loss of biological diversity, after habitat destruction
The Bureau of Land Management, our nation’s largest public landowner, estimates that 2,300 acres per day of its land are being lost to invasive plants. Nearly 4,000 acres per day are estimated to be lost to invasive weeds nationwide.
If you find yourself alarmed by these facts, you are not alone. Local and state agencies, groups, and individuals have been quietly pouring money and resources for years into our local roadsides, parks, natural areas, and agricultural areas to combat this pressing problem. This web site is dedicated to raising public awareness of this issue. The battle against invasive weeds cannot be won without public awareness and support. As a homeowner, landowner, or land manager, your actions have a direct effect on this problem because many weeds escape from yards and gardens.
This web site has, in addition, been prepared to help you understand the problems of invasive weeds, identify them around your home and community, and take direct action to save our natural and agricultural resources from this threat.
What Exactly are Invasive Weeds?
Over the past 150 years, many non-native plants have been introduced to our region, both intentionally and accidentally. The vast majority of these plants coexist with native species and are ecologically harmless. What makes a plant invasive is its negative impact on the environment. Invasive plants have the ability to spread and crowd out native plants and quickly dominate a given area. This is why invasive weeds are distinguished from those weeds that occur in small numbers and are relatively innocuous.
Invasive 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 nonnative plants become invasive while some don’t; but because invasive 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. Invasive weed species can proliferate and spread over large areas. Some are able to completely displace other vegetation, forming a homogenous (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.
Invasive weeds are exotic plants that have reached Dallas 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 invasive weeds are spread by wind blown 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 invasive weeds spread by sending rhizomes (long underground roots) to uninfested areas. Many invasive weeds can be easily controlled through proper management. Mowing, cutting, burning, competitive seeding, cultivation, herbicide usage, etc., are some of the various techniques used to combat weeds. Several of the State of Iowa and Dallas County’s worst invaisve weeds are very difficult to control, such as Canada Thistle, Japanese Knotweed, and Purple Loosestrife. 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.
Why Should I Control Invasive 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. Invasive weeds are also a leading cause of species endangerment under the Endangered Species Act.
What are Noxious Weeds and who Controls them in Dallas County?
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.
|Canada thistle (Kirk Henderson)
||Musk thistle (Plant Conserv. Alliance)|
All landowners are required to control those weeds on their property that have been declared noxious
by the State of Iowa or by Dallas County.
Noxious 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 Dallas County Weed Commissioner enforces the Iowa Noxious Weed Law and the County's Noxious Weed Control Program. Click here
to find out what weeds are listed noxious in Dallas County.
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 Dallas County Weed Commissioner is located at the Secondary Road Dept., 415 River St., Adel, IA 50003. Phone (515) 993-5868 x 210. If you wish to file a weed complaint, weed complaints will be handled as follows:
The complaint will not have to be signed and may be phoned at the number above. State the weed species in question, the legal description of the property, the location of the weeds on the property, the owners of the land, and the tenants or persons in control of the land. Forms are available at the Weed Commissioner’s office and will be mailed on request.
What Can I Do to Help?
Don’t Plant Invasive Weeds. Be selective when you choose plants for home landscaping. Some invasive plants, such as purple loosestrife varieties, are still illegally sold in nurseries and garden shops, so beware! If you plant these in your yard, they may escape into nearby areas and become a problem by displacing native species. Not all non-native plants are invasive. There are many beautiful horticultural plants available for you to choose from, without contributing to the invasive weed problem. Also consider planting native species in your home garden. Natives offer a good choice for home landscaping because they are well adapted to local conditions and often thrive with less care than required by many non-native plants. Native plant gardening also enhances the value of your yard for local wildlife including birds and butterflies.
Remove Invasive Weeds. Be on the lookout for invasive weeds and remove or report them whenever possible. You may have invasive plants already growing in your backyard. Birds and other animals may eat the seeds of these plants and then travel to nearby uninfested lands, resulting in the spread of invasive weeds. You can help stop these invasions by removing the source plants. Talk to your neighbors and local greenhouses about the problem and share your concerns. Report sightings on public lands to the land manager. And if you do remove these plants from your own land, be sure not to spread the seeds when disposing of them.
Help Prevent the Accidental Spread of Invasive Weeds. When you venture into natural areas, roadsides, or any place with invasive weeds, be aware that you could be introducing or carrying invasive weeds inadvertently. Check your shoes, socks, clothing, etc., which might carry seeds. Another important thing you can do is to try to limit soil disturbances on your property. Invasive weeds thrive on disturbance and can quickly colonize areas that don’t have a good vegetative cover. If invasive weeds are moving in, try to control them before they get well established and the area is infested.
Educate Yourself And Spread The Word. Become better informed about how to identify invasive weeds, how to avoid spreading them, and how to control them. The battle to control invasive weeds cannot be won without public awareness and support. Share what you have learned so that others can join in the WAR ON WEEDS!
Here are some groups and agencies that can provide further information or assistance on noxious weeds:
- Dallas County Extension Service (515) 993-4281
- Iowa Department of Agriculture & Land Stewardship (515) 281-5321
- Dallas County Natural Resource Conservation Service office (515) 993-3413
- Iowa Department of Transportation (515) 233-7729
- Iowa State University (Agronomy) (515) 294-1923
- The Nature Conservancy (515) 244-5044
Material for this website was adapted from: Johnson County's Secondary Roads / Noxious Weeds pages with permission from the Johnson County IRVM program of Johnson County, Iowa.