Pond primer: Chemical treatment option measures up


SALEM, Ohio – Chemical use is an attractive option for many pond owners who want to prevent and control growth of algae and aquatic plants.

The first step in chemical use is plant identification since classes of plants – floating, submerged and emerged – require different treatments.

“Without the proper identification, you could be using the wrong type of treatment and wasting your money,” said Ernie Oelker, agriculture and natural resources agent with Ohio State University Extension in Columbiana County.

“Water-meal and duckweed might look a lot alike, but need two different chemicals,” he said.

Plants can be identified by using picture guides available from herbicide manufacturers and at garden and farm supply stores, or by taking a sample of the plant to your county’s Ohio State University Extension office.

Can’t have one … Proper identification also helps a pond owner choose which type of herbicide or algaecide to use, and to determine application rates.

Choosing which chemical to use is influenced by pond use, according to Eric Norland, extension natural resources specialist. Many chemicals require waiting periods or restrictions depending on whether the water is used for domestic or agricultural purposes, irrigation, swimming or fishing.

It’s also important to consider the amount of chemically treated water flowing from a pond through spillways, and how the chemicals might influence downstream habitat, wildlife and water use.

Without the other. Application rates listed on product packaging should be followed closely. In order to use the correct amount of chemical, a pond owner needs to first know the pond’s area.

“You need to measure as precisely as possible. And remember, the pond isn’t the same depth today as it was 25 years ago when it was first built,” Oelker cautioned.

To determine surface area and volume contact a contractor or technician involved in pond construction. In addition, some Farm Service Agency offices may have aerial photographs that show a pond, from which calculations can be made.

Pond owners can also make their own measurements. For more information on these calculations, contact your county extension office.

Measurements should be taken whenever there is a significant change in surface area or depth. Average depth should be recalculated every five years to account for gradual sediment filling of the pond.

Treatment tips. Oelker offered the following tips for chemical controls:

* Don’t broadcast copper sulfate granules. The chemical will show better results if dissolved in a bucket of water first, then sprayed onto the water surface with a plastic sprayer.

The chemical can also be used by dragging a burlap bag filled with the granules behind a boat through the water. The active ingredient is also available as Cutrine in liquid form.

* Pay close attention to labels. Some labels give application restrictions that also help the pond owner save money, for example, not applying treatment before rains or when it won’t be useful.

Caution should be exercised when treating, Oelker said, since chemicals like copper sulfate can cause oxygen depletion in the pond and endanger fish.

* Stay away from “look-alikes.” The active ingredient in some chemicals is sometimes the same as in other formulations. However, those formulations aren’t labeled for aquatic use and should not be used as such. For example, there are several products that contain glyphosate, including Roundup and Rodeo, but only Rodeo is labeled for aquatic use.

Accountability. “Your pond is water of the state, so understand the risks of chemicals used. If you put herbicide in the pond and it goes downstream and causes some damage, you’ll pay. Make sure you know what you’re doing,” Oelker urged.

(You can contact Andrea Myers at 1-800-837-3419, ext. 22, or by e-mail at amyers@farmanddairy.com.)

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