Oklahoma Water Resources Center

If a pond was weedy last year, it probably will be weedy this year

STILLWATER, Okla. – Reeling in a couple pounds of pond weed may be somewhat of a challenge, but it is nowhere near the amount of fun as hooking into a good sized fish and battling it all the way to the shore.

Pond owners can follow a general rule to try and eliminate this occurrence from their fishing experience: if your pond was weedy last year, then chances are you will have a similar problem this year.

There are two main causes of excess aquatic plant growth, said Marley Beem, Oklahoma State University Cooperative Extension aquaculture specialist.

“The first is shallow areas. These are ideal for emergent aquatic plants like cattails, bulrush and many others,” Beem said. “Try deepening shallow edges to minimize the area that is less than three feet in depth.”

Shallow areas are often caused by heavy cattle access or erosion in the watershed. Steps should be taken to prevent these situations. The second major cause of pond weed problems is a high level of fertilizer runoff.

“Typically this fuels the growth of algae,” Beem said. “Try reducing the amount of phosphorous that is applied in the watershed. If that’s not possible you may wish to consider aquatic dyes to reduce the amount of light getting into the water column.”

If these problems are not addressed, plants will tend to come back quickly following herbicide application or most other types of treatment.

“Spring is the best time to monitor pond plant grown with an eye toward doing something about it before it gets out of hand,” he said.

There are a couple of options pond owners can choose in ridding their pond of overgrown aquatic plants. The first solution is the use of herbicides, which is typically quite effective, but there is some risk involved.

“One of the main risks in applying herbicides to aquatic plants is that too much plant material will be killed and, as it decays, will use up all the dissolved oxygen in the pond and suffocate the fish,” Beem said. “This risk is much lower in the spring and is usually less work and lower cost to treat early because you are treating a smaller area.”

As some pond owners may be concerned about the safety of using herbicides, Beem said those that are labeled for aquatic use have undergone extensive testing to minimize the chance of harming fish, other organisms and the health of people eating the fish.

However, there are nonchemical approaches that can be tried in some situations. Grass carp should be used with caution, especially in fishing ponds as bass and bluegill need submerged plant beds and grass carp tend to eliminate these.

“If your main problem is not being able to cast because of weedy conditions, you might instead consider spot treatments with herbicides to open up a few stretches of shoreline,” Beem said. “From the point of view of the fish, about 20 percent coverage of the pond by aquatic plants is ideal.”


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 74078-001
Phone: 405-744-4490
Fax: 405-744-5739
E-Mail: sean.hubbard@okstate.edu

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