Oklahoma Water Resources Center

Herbicides can help with pond management, but be careful


STILLWATER, Okla. – Ponds that are overgrown with pond weeds are not only unsightly, but also very difficult to fish or even enjoy a cool summer swim

Herbicides are a tool that can be used to help manage these weeds.  However, while they are a quick means of knocking back pond weeds, Marley Beem, Oklahoma State University Cooperative Extension aquaculture specialist, warns that care should be taken in the use and selection of herbicides.

“Using improper herbicides puts you and the environment at risk. We all like a bargain, but we should not consider using herbicides, like Karmex, which are not specifically labeled for ponds and other aquatic sites,” Beem said. “Karmex use often kills pondside trees and it has not been tested for the safety of fish and the people who eat those fish.”

Even with proper aquatic herbicides, Beem said there are some sites in which herbicides should never be used. These include ponds that are excavated below the water table and fill from the bottom up; ponds in places like the bottom of gravel quarries or sandy river bottoms as groundwater may flow into someone’s water well; and ponds that can overflow into public waters.

“Occasionally plant management is needed in creeks or flowing water situations. In this case, contact state agencies, such as the Oklahoma Department of Wildlife Conservation, before any application is made,” Beem suggested. “When what you do on your property may affect others, be very cautious and proceed only with expert advice and approval.”

County Extension agriculture educators will be able to help pond owners in developing a pond weed management plan. It is essential that you understand how to calibrate your application method, calculate the right amount of herbicide to use and be aware of the needed withdrawal time to protect livestock, swimmers and other pond users.

“Another hazard in treating pond weeds is killing too many at one time and causing so much plant decay that all dissolved oxygen is used up and your fish die,” Beem said. “Take care in herbicide selection and use so that your enjoyment of the pond is not overwhelmed by problems resulting from an herbicide application gone wrong.”


Oklahoma State University, U.S. Department of Agriculture, State and Local Governments Cooperating: The Oklahoma Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, national origin, religion, gender, age, disability, or status as a veteran, and is an equal opportunity employer.

Sean Hubbard
Communications Specialist
Agricultural Communications Services
145 Agriculture North
Oklahoma State University
Stillwater, OK 74078
Phone: 405-744-4490
Fax: 405-744-5739
Email: sean.hubbard@okstate.edu

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