Pond Boss Forums Thread Like Summary - Controlling Watershield

Our pond is 5 years old and about 3/4 acre. The watershield started out just along the shore in a few places but now is spreading outward from shore all around the pond. I am looking for a chemical treatment to control it from getting too bad. Winter has it beat down for now so I would like to start treating it early spring when it starts growing again. Thanks in advance for any help.

October spraying is fine if all goes well. Esshup gave great advice, and I'm not disagreeing with him, but a late September spraying would allow plenty of time to do a followup spray if needed.

I try to make most decisions based on best case/worst case scenarios. If you spray in late September or late October, and the application takes, then all's well. If the September treatment doesn't take, then there's time to reaccess, and reapply if needed. If you spray in late October, and it doesn't take for whatever reason, then another treatment may not be as effective. Systemic herbicides take longer to work, so let's say it takes 7-14 days before a proper evaluation can be determined. If a late October application doesn't take, then you're looking at 7-14 days for discovery + a day or two for evaluation and application prep + another 7-14 days to evaluate the second treatment. That could potently get you to mid to late November. As I said, esshup gave great advice, but I like a little wiggle room after a herbicide treatment.

I'd wait until the leaves on the water surface get to be about 50% the coverage that they were last year, then hit them with the liquid. That will help minimize the number of times you will have to spray.

Imazapyr is what I use for various surface plants. A little more expensive than glyphosates, but it does a better job. Be sure and use a good non-ionic surfactant also.

Watershield Control

Figure out the area that the watershield is covering and apply the Ecomazapyr at the rate of 2-4 pints per acre, and mix in the surfactant at the rate of .16 to .64 fl. oz. per gallon of tank mix.

If you mix the solution too strong (more is NOT better when it comes to herbicides to control plants) you can shock the plant and it basically shuts down, NOT translocating the herbicide to the roots where it's supposed to go to kill the plant vs. just giving it a haircut. You did the correct thing, applying it in the Fall when the plants were taking nutrients down to the roots for the winter.

What rate did you mix it at and spray it at?

That is correct, .16 to .64 fl. oz. per gallon of tank mix. (1 qt per 100 gallons of tank mix)

As for the amount of water to mix with the Ecomazapyr, mix 5 to 30 gallons of water per surface acre. For watershield, since the leaves are floating on top of the water, you don't need to calculate ac/ft of water, just the surface area that you are spraying.

Ideally you want to use enough water to cover the whole area that you are spraying, but not to the point of too much runoff from the leaves. Imazapyr will translocate to other plants nearby if too much is used (i.e. shoreline trees or plants) and will kill or at least shock them. You don't want to over-apply it but at the same time you don't want to under apply it either. Plants will develop a tolerance to some chemicals if they are used in too low of a dosage for a number of treatments - like a vaccine teaches our body to fight off something that could kill us if not vaccinated.

When I am spraying, I will mix in 8-16 ounces of a pond dye to the tank mix so I can see where I sprayed.

You want to treat when the plants are actively growing, treating in the Fall is best for plants that have an extensive root system, but I understand that you want to utilize the pond too. So, just be prepared to possibly treat the plants again in the Fall if they pop back up in late summer. Up here, we like to treat those types of plants in mid to late September. Down there I'm guessing (and this is just a guess) in mid to late October.

Just wanted to provide some follow up to my earlier post. I actually elected to go with the Navigate granular product initially to see if it willl have any effect - it it doesn't work I am going to scale up to the liquid products you all recommended. Honestly the granular is just much easier for me to apply and the product warnings on the liquid product kind of gave me the heebie jeebies...

Good news is the Navigate does seem to be working - not 100%, but definitely having an effect. I applied about 3 weeks ago. Other good news is I have small bass and bluegill making beds in portions of the pond that were previously choked out with water shield which is exactly what I was hoping would happen. Thanks for all of the help and good suggestions!

Cullen

Update on the watershield. On half of the pond the watershield has been elinated and the other half that wasn’t sprayed has died back to about half as much as normal. We got too hot too fast down here so I will treat the other half in fall when it cools off so I don’t have any O2 issues. Most likely that won’t happen until late October though.

Thanks to everyone that had any input into getting rid of it, I think I am on the right track now.