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I have water shield. What should I use, and will it hurt the lilies I want to keep? | Ponds & Lakes Q&A

Q: I have water shield. What should I use, and will it hurt the lilies I want to keep?

Q: I have water shield. What should I use, and will it hurt the lilies I want to keep?

Gordon – Spring Mills, PA

A: Water shield, scientific name Brasenia schreberi, can be a tough enemy to battle one it is established in your pond – but with some effort and the right tools this invasive aquatic plant can be controlled. Here’s what you need to know.

Water Shield Identification

Water shield, also known as Dollar Bonnet, is a floating-leaved plant that produces a small, oval pad like a water lily but without its noticeable V-shaped cutout. The leaves appear green on top and reddish-purple on the bottom and stems, and they have a distinctive gelatinous slime on their undersides. The plant also produces small, dull purple or reddish flowers that rise above the surface and consist of three to four sepals and petals.

Like other invasive aquatic plants, water shield spreads via seeds and its root system – which makes it doubly difficult to control. Beneath the surface, the long leaf stems reach the bottom where they attach to long creeping root stalks that are anchored in the mud. To control the plant, you really need to destroy the entire plant, roots and all.

Battling Water Shield

You could try to control this problem plant mechanically by cutting and yanking it with razors and rakes, but that won’t be enough to get rid of it. The plant will just regrow from its remaining roots. And if you want to attempt biological control, you’re out of luck as one doesn’t exist.

Destroying this plant means bringing out the big guns: the chemicals. Active ingredients that have been proven successful in treating water shield which include glyphosate and diquat.

Pond Logic® Shoreline Defense® Aquatic Herbicide contains glyphosate, which is a systemic killer that will work all the way down to the plant’s roots after a single use. It has no water use or temperature restrictions, so you can safely use it in ponds used for drinking water, livestock and irrigation.

Another option is Pond Logic® Ultra PondWeed Defense® Aquatic Herbicide. It’s a quick-fix solution that will kill the floating water shield foliage and tackle some other nuisance weeds in your pond. However, it may not penetrate down to the roots so you’ll need to use it repeatedly, and it has some water use restrictions associated with it.

What About the Lilies?

Both Shoreline Defense® and Ultra PondWeed Defense® should be combined with Treatment Booster™ PLUS are applied via a tank sprayer to the foliage that’s on the water surface. If you carefully spray the herbicide onto the water shield leaves on a calm day and prevent any from landing on your water lilies, they’ll be just fine!

One word of caution: Chemical control brings with it a chance of oxygen depletion caused by the decomposition of dead plant materials. If your pond is heavily infested, treat the weeds in sections, and let each section decompose for about two weeks before treating another section. Be sure to keep your aeration system running.

Pond Talk: Have you battled water shield in your pond or lake? If so, how did you win the fight?

Control Persistent Aquatic Weeds - Pond Logic® Shoreline Defense®

My pond is covered in duckweed. What can I do to treat this stuff? – Ponds & Lakes Q & A

Duckweed

Q. My pond is covered in duckweed. What can I do to treat this stuff? – Tony in Indiana

Friend or Fowl
A: For the lucky pond guys and gals out there who have never experienced duckweed in their pond, or those of you who think you may have it but are unsure; duckweed is a very small floating plant with kidney shaped leaves and a small hair-like root hanging below. It is approximately the size of a pencil eraser and is frequently misidentified as algae. It can cut off sunlight to submersed plants and cut off oxygen to fish and other wildlife. Duckweed is an extremely prolific grower and can quickly cover an entire pond making it frustrating to treat and maintain. More often than not, duckweed is introduced into your pond by hitching a ride on the feet of waterfowl.

Don’t Go Daffy Over Duckweed
There are two great options available to you in your fight against duckweed. Choosing the product that is right for you depends on the time frame you have to treat your pond. For fast acting, short term results, you can use a contact herbicide like Ultra PondWeed Defense® . Treatments with these types of herbicides work best on mature aquatic plants that are in a contained environment. Multiple treatments are typically required for effective short term control. It is important to remember that whenever you are treating large amounts of weed growth, only treat one third of the pond at a time and implement aeration whenever possible to ensure safe oxygen levels. When treating with Ultra PondWeed Defense®, we suggest that you use a tank sprayer to apply the herbicide directly onto the weeds. Ultra PondWeed Defense® has some water use restrictions, see label for details.

For long term treatment of duckweed, we suggest using Sonar™ A.S.. By adding Sonar™ A.S. to your pond in early Spring, you will inhibit the weed’s ability to produce carotene, a pigment that protects the plant’s chlorophyll. Without carotene, the sun quickly degrades the green chlorophyll and the weed dies. Sonar™ A.S. must stay in your pond for up to 90 days for maximum results, so if your pond has a constant overflow or you are experiencing heavy rains, you may need to include additional treatments. Sonar™ A.S. is degraded by sunlight, so when applying, make sure you spray the product directly into the water and not onto the plant foliage itself. Also, adding Nature’s Blue™ Pond Dye after treatment will help prevent sun degradation as well as track water dilution from heavy rains. Sonar™ A.S. has a 30 day irrigation restriction.

POND TALK: Have you ever experienced duckweed in your pond? What did you use to treat it?

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