As the Weather Cools Off, So Will the Pond Weeds!

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I have received emails from folks all over the county about different weeds that they have in the their ponds, and I hope that the information I have provided helped to ease the problem, if it didn’t get rid of it. As we approach the cooler months, it is time to take a step back and start to make a plan of action for next year, if you are still dealing with weeds in/on your pond.

If you are making chemical applications, it’s time to stop, because as the air temperatures get cooler, the water in your pond is going to cool off, and once that happens the chemicals are going to be less effective than during the warmer months. Typically, pond weeds will overwinter on the bottom of the pond so it becomes very difficult to get any type of treatment down there to be effective. Most of these chemicals do get rather pricey over time, and I don’t want you to waste money on an application that isn’t going to do the intended job.

Going along with that thought, if you are looking to stock some Triploid Grass Carp in your ponds, this is an ideal time to do so! They will not control every weed that may grow in your pond but they are a cost-effective alternative to chemicals for some weeds. (This is a great time to send me pictures and I can tell you whether they will help with your problem or not!)  You usually can get about 7-10 years out of grass carp before their appetite slows, and if you still need them, then you can add more.

As we get to next year, and you know you will have a problem, it may be worth considering using a pond dye to darken the color of the water in the pond. This helps to reduce the amount of sunlight that makes it to the bottom (where the weeds are hibernating), and can delay the amount of time before weeds start to show. One thing about pond dye is that it works on concentration, so if there is a heavy rain event, you may have to add more for it to remain effective. I wish that dye would kill weeds, but it just prevents them for a little while. I generally recommend trying to put a pond dye in around the beginning of March, but it is highly weather-dependent, so that recommendation is very broad, this far out.

If you have any questions about anything in this post, or if you have some weeds that you need help trying to get rid of, please feel free to email me at or contact me at the office at 336-570-6740 and we will try to get it figured out!

Written By

Dwayne Dabbs, N.C. Cooperative ExtensionDwayne DabbsExtension Agent, Agriculture - Field Crops, Pesticide Coordinator Call Dwayne E-mail Dwayne N.C. Cooperative Extension, Alamance County Center
Posted on Oct 7, 2020
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