Not Your Everyday Garden Weed
Invasive species are more than just garden pests. They can profoundly affect, and irreversibly damage, natural habitats.
They do this in a number of ways. Some species exclude native plants by being better competitors—they are more aggressive, can get in first, and multiply quickly. Some have toxins that adversely affect other plants. Others actually change the chemistry of the soil, making it less hospitable to natives.
In addition, invasive species may increase flammability of the landscape, increasing fire frequency and severity of fires.
When the plant community changes, wildlife may be harmed as well. Many noxious weeds are unpalatable or even toxic to native animal species. When the habitat becomes intolerable, wildlife must move or die. Livestock and croplands also can be seriously impacted by invasives, causing significant economic losses.
Invasive species are a tremendous problem for all these reasons. So what can we do to control them? It’s a complex issue but there is quite a bit that can be done, by both individuals and communities.
Invasive species come from all over the world. About half of the invasive species in California were introduced intentionally—as ornamentals, erosion control, or for other reasons. Others came in accidentally, through contaminated crop seed, on machinery, and numerous other routes.
While the vast majority of exotic plants stay in their gardens or are otherwise benign in the environment, a small number, perhaps 10%, escape and become pests.
Without their native controls, such as diseases and predators, these plants can quickly wreak havoc on the environment.
Each pest species has a unique story, which includes its life history, effects on the environment, tolerance to various climate regimes, etc. Effective control must be individualized based on knowledge of the pest plant.
Using integrated weed management techniques, you can learn to manage invasive species on your property.
- Cal-IPC (California Invasive Plant Council) has a website with an immense amount of information, including an invasive plants inventory database, listings of invasive plants by category, descriptions of invasive plants and control methods, research, field courses and other activities.
- Weed Management Areas. There are Weed Management Areas in most parts of the state. Find your local contact at
- CA Department of Food & Agriculture (CDFA) rates noxious weeds in California (Cal-IPC rates them separately).