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Watershield (Dollar Bonnet)


Ecological Importance

Provides excellent habitat for northern pike, largemouth bass and sunfish; highly decorative----often planted in water gardens. Deer, beaver, muskrat, nutria and other rodents will consume the leaves and rhizomes of watershield, while the seeds are eaten by ducks.


Watershield can grow and reproduce rapidly if not maintained correctly. This occurs when there is an excess of nutrients in the pond. Dense growth of watershield (dollar bonnet) in shallow water areas sometimes interferes with boating and recreation.

Plant Description

Leaves are oval in shape with smooth edges. Stem is attached to the middle of the leaf. Rust colored underside. A clear jelly-like coating covers the underside of the leaves and stems on mature weeds. A dull purple flower develops in early summer. Treat before jelly-like coating develops.

Watershield reproduces through both seeds and rhizome spread.

Water shield is sometimes confused with young water lilies (either white water lily or yellow water lilies (spatterdock). However, water lilies have a split in the leaf from the edge to where the stem attaches. The leaves of water shield are completely oval, with no split.

Hints to Identify

Leaves are similar to a lily pad's but are smaller and have no slit; flowers are smaller than the water lily's; stem is attached to the center of the leaf; has a clear, jelly-like coating on the stem and the underside of each leaf.

Homeowner Treatment Options
Imazapyr 4 SL
Renovate Max G
Shoreline Defense
Sonar RTU
*Aquatic Biologists recommends implementing preventative management techniques and physical removal prior to, or in conjunction with treatment.


Common Application Questions

Q. How much should I treat?

A. Because watershield provides good habitat for fish, be conservative, treat only enough to obtain access.

Q. Which of the options listed works best?

A. This is a difficult question to answer. Selecting the best option depends on many factors including:

  • What growth stage is the plant in?
  • Water temperature.
  • Surrounding area.
  • Other plants near or in the treatment area.
  • Size of the problem area, etc.
Q. When is the best time to treat?

A. Once water temperatures are around sixty degrees or warmer. Herbicide treatments are best done in early summer before the jelly-like coating develops on the leaves.

Q. How often do I need to treat Watershield?

A. Watershield control can last anywhere from two to three years or more depending upon adjacent Watershield influence. An application may be required three to five weeks post treatment. Navigate is a systemic herbicide that kills the root structure.

Q. How long before I see results?

A. Generally within two weeks things will be cleared up. Maybe a bit longer, Navigate Granular is a bit slow but very thorough in the end result.