Wild Ones   Suggestions for Controlling Invasive Species  
By Ken Solis

Removing or killing an invasive plant often greatly depends on the particular species. Some general rules for dealing with invasive weeds are:

1. Eradicate them early before they become established. Most invasive weeds produce a prodigious number of seeds or spread by extensive rhizomes. Usually you will have to spend many years fighting seedlings after you have removed the mature plants.

2. Work from the least infested area(s) toward the worst infested area(s). You’ve already lost the battle or will spend many hours for many years dealing with badly infested areas; keep the less infested areas from reaching that point.

3. Consider the overall botanical quality of the area. In Milwaukee, we’ve had to give up in many parks because we were essentially pulling garlic mustard to benefit other weeds such as buckthorn, creeping Charlie, or burdock. We try to concentrate on areas that have a lot of good native plants already established.

4. Know thy enemy. There are a number of educational resources to help you learn the best way to fight an invasive weed. The wrong approach may cause even more work. For example, cutting down a black locust tree will induce it to send up many shoots from its root system. On the other hand, a particular feature of a weed species may work to your advantage. Buckthorn leaves stay green later than most natives and garlic mustard (first year growth) stays green through the winter. Therefore, if you decide to spray the appropriate herbicide in the late fall, you will do little harm to native species.

5. Environmentally minded people are rightfully concerned about the use of herbicides. However, as with nearly any similar issue, it is a matter of weighing the risks against the benefits. If it appears that your favorite natural area is going to “die” due to an overwhelming infection of invasive weeds, you might decide that the benefits of the herbicide as an antibiotic outweigh the risks.

Ken Solis is vice-president of The Park People of Milwaukee, and chairperson of Milwaukee's Weed-Out program. An emergency physician in “real life,” Ken is a member of the Milwaukee-Wehr (WI) Chapter of Wild Ones.

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Updated: Jun 12, 2005.