Invasive Species Threats & How to Control Them

Invasive species are invading Iowa and threatening Iowa's native species and Ecosystems. This page is meant to inform people of these threats and to provide information to control these species.

Garlic Mustard

Driftless Land Stewardship has developed a good program for attacking garlic mustard that they claim is very effective. Using it, they have taken massive infestations to "manageable levels" in 2 years. Their success has led some in the Wisconsin DNR to adopt this method. The method is summarized in the web page here.

Because DLS's method differs from other methods in some major ways, it is summarize it below, and explain a few "new thoughts" regarding this 4-step process:

  1. SPRAY all plants you can find during the fall, winter, early spring, while native vegetation is dormant. DLS has found that label concentrations of Roundup, applied any time in winter when daytime temps exceed freezing, are effective. (This differs from the normal recommendation that Roundup onlyworks during the active growing season.) You may need to wait months for death to become apparent, but by spring the plants die. Dormant season spraying drastically decreases the amount of hand-pulling necessary the following year.
  2. BURN in late spring - DLS recommends April - after the first flush of new GM seedlings appear. This kills newly germinated, cotyledonous GM, and opens up the seedbed so future GM seedlings appear in a single massive flush. DLS does NOT burn in the fall on sites with garlic mustard. Burning top-kills the older plants, but roots remain viable and leaves resprout. Also, because top-killed plants cannot be sprayed during the winter, fall burns increases the amount of hand-pulling that must be done the following year.
  3. HAND PULL any remaining second year plants, making sure that you get the root. Dispose of them appropriately.
  4. BURN OFF new seedlings with a propane torch as they appear. This task is easier after leaf litter has been removed by burning, because seedlings are easier to see.

Repeat the process the following year.