Glechoma Hederacea - Control

Control

As is often the case when a plant has this many familiar names, Glechoma is familiar to a large number of people as a weed, a property it shares with many others of the mint family. It can be a problem in heavy, rich soils with good fertility, high moisture, and low boron content. It thrives particularly well in shady areas where grass does not grow well, although it can also be a problem in full sun.

Small infestations can be controlled through hand weeding; repeated weeding is required because the plant is stoloniferous and will continue to spread from its roots or bits of stem which reroot.

Glechoma is unusually sensitive to boron, and can be killed by applying borax (sodium tetraborate) in solution. The ratio is eight to ten ounces of borax dissolved in four ounces of warm water, diluted to 2.5 U.S. gallons of final solution, to be sprayed evenly over precisely 1,000 square feet (100 m2) of lawn "no more, no less". Note that despite being a "natural" treatment, boron is toxic to other plants and to animals at only slightly higher concentrations and, being an element, does not break down; therefore the long term effects of this technique on soil or groundwater, although not well documented, can be assumed to be unfavorable. More recent research discounts the efficacy of borax, primarily because finding the correct concentration for a given area is difficult and the potential for damaging desired plants.

Aside from mechanical removal or borax treatment, the other alternative for Glechoma infestation is use of commercial herbicides. There is some disagreement over the effectiveness of various herbicides, with dicamba (Trimec and Weed-B-Gon) and 2,4-D being described variously as both effective and ineffective by different sources. Some or all of the disagreement may be due to the existence of subpopulations which have differing susceptibilities to different compounds, as well as to differing rates of application. To avoid generating herbicide resistance, the same product should not be used several years in succession; rather, various products should be used in rotation. Triclopyr has also been described as effective, and Clopyralid, MCPP, and quinclorac as ineffective. Fluroxypyr and Confront have also been described as effective, but sales of both are restricted to professionals. Two applications ten to fourteen days apart are necessary; also, the ability of the surviving plants to regenerate after 24 days can require a second treatment four or five weeks later, and even more followups.

In addition, the timing of application may play a role in the effectiveness of the herbicide, as well as the perception of effectiveness. For instance, fall is usually the best time for use of broadleaf herbicides; however a slow acting herbicide like triclopyr applied in the fall may not appear to have been effective until the next growing season.

Other techniques reported effective are to fertilize with greater than two pounds of nitrogen per thousand square feet annually, and use of the preemergence herbicide, isoxaben. In extremely difficult cases, a short-lived full-spectrum herbicide such as Roundup is used to kill the entire lawn, and it is reseeded from start.