Knowledgebase

Duckweeds and cattails Pond Management #869987

Asked May 24, 2024, 5:14 PM EDT

Dear Cornell Cooperative Gardeners, My husband and I are new home owners in Mount Tremper. We are part of the watershed and have a pond on our property. The pond is covered in duckweed and cattails. We got in touch with a local pond management service and they suggested to treat the duckweed with Flumioxazin and glyphosphate for the cattail. Before we do any treatment we would like to make sure we are not harming any of the potential life that exist in the pond already. We noticed there is a snake, some small turtles and many frogs. We really appreciate any advice or recommendations you might have for dealing with this. Thank you very much. Warmly, Iva Gocheva

Ulster County New York

Expert Response

Here are 3 photos of the pond with the duckweed. 


The Question Asker Replied May 24, 2024, 6:37 PM EDT

Good morning, Iva,

Regarding Cattails, they can be quite desirable in a pond. However, if they are coming in too thickly, they can reduce your enjoyment. If you want to control the growth, without using chemicals, you will need to disrupt the root system through cutting, hand pulling or dredging. Pulling them out while they're young is best, otherwise, cutting them down 2-3 times in the summer helps. If you decide to use chemicals, you will need to obtain a permit and only use specific herbicides for aquatic species. 

Duckweed management without chemicals involves reducing lawn fertilizers and leaf litter. Skimming the surface and disposing of the debris may help. 

You can also call a pond management specialist, Jake Wedenmeyer, at<personal data hidden>. 

Thank you for contacting Ulster County Cooperative extension.

Best regards,

Master gardener, Peggy  

An Ask Extension Expert Replied May 29, 2024, 11:25 AM EDT

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