Water Shield (Dollar Bonnet)

Control Options

Cultivation Options

Description of This Plant

Control Options

Mechanical/Physical

Water shield can be cut and the roots can be dug up but physical control is difficult because it can reestablish from seeds or remaining roots.

Biological

There is no known biological control for water shield.

Chemical

The active ingredients that have been successful in treating water shield include 2,4-D (E), glyphosate (G), fluridone (G), and imazapyr (E). E = excellent, G = good

Navigate and Aqua-Kleenare 2,4-D compounds that have been effective on water shield. 2,4-D compounds are systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.

Rodeo, Aquamaster, Eraser AQ, Touchdown Pro, and AquaNeatare liquid glyphosate formulations and have been effective on water shield. These are broad spectrum, systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) will have to be added to the glyphosate solution for good results.

Sonar and Avast are fluridone compounds, come in both liquid and granular formulations, and have been effective on water shield. These are broad spectrum, systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.

One danger with any chemical control method is the chance of an oxygen depletion after the treatment caused by the decomposition of the dead plant material. Oxygen depletions can kill fish in the pond. If the pond is heavily infested with weeds it may be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control the oxygen depletion.

One common problem in using aquatic herbicides is determining area and/or volume of the pond or area to be treated. To assist you with these determinations see SRAC #103 Calculating Area and Volume of Ponds and Tanks.

Many aquatically registered herbicides have water use restrictions. For General Water Use Restrictions click here.

To see the labels for these products click on the name. Always read and follow all label directions. Check label for specific water use restrictions.

Cultivation Options

Water shield can be propagated from seeds or by transplanting root systems into shallow water during the early spring. However, water shield can be an aggressive invader of ponds.