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.

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

I bought a gallon of that and surfactant late last year. I test sprayed a small section with it but it didn’t kill anything. I am pretty sure that is what I used anyway. I will check next trip out there and verify then report back here.

That's strange that it doesn't work. Let us know if it is Imazapyr( and the trade name) and the surfactant used, and we'll try to figure it out. Imazapyr and 2 4-D are the only 2 herbicides that Texas A&M rates "Excellent" for water shield.

What time of year did you do your application?

I will follow up after my next trip there. I used it late October if I remember correctly.

I used Ecomazapyr 2 SL and the surfactant is Activator 90 non ionic surfactant.

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?

Thanks for the advice, I don’t remember what I mixed it at last fall. I only sprayed a small section for a test because it was still hot down here and I didn’t want to take a chance of killing it all and have low O2 in my pond when it decomposed.

Am I reading your surfactant amount right of .16 to .64 oz per gallon? Thats not very much and would be hard to measure but I can do the math and figure it out.

The watershield is all around the pond along the edges out about 10-15ft in the worse spots on the deeper end and worse on the shallower end.

When should I spray again, I was thinking this spring when it first starts growing. Since the water will stil be cool I feel better about spraying everything as it starts growing.

The pond is about 3/4 acre and 8ft deep in the middle and tapers uo to the shore for ost of it and about 5ft deep on the other end.

You said to apply the ecomazapyr at 2-4 pints per acre, with how much water for this rate?

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.

Scott, I wouldn't spray that late. Mid to late September also sounds good to me, and the OP's 2021 October treatment didn't work. I know you mentioned it, but spray the foliage, not the water.

Thanks for the advice and info. I will spray them when they start growing again and re-treat as needed later in the year.

I know my test spray didn’t work but I don’t think I used enough chemical. Why don’t you think mid to late October is a good time? We typically don’t see the first frost until late November or early December. I don’t have a problem spraying in September but was just wondering your thoughts on this.

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 totally understand and thanks for your point of view. I will see how it goes this spring and may spray in September like you advised and that will gove plenty time for a second treatment if needed. Thanks for your help.

The granular 2,4,D (Navigate?) is an option or even a combo? I tried some on watershield that was spreading and it seemed to work. Not as good on the larger lilly pads. That said I have never seen Imazapyr not kill stuff.

Granular 2,4-D will work well, the only issue is getting it to the roots of the plant. If the Watershield is thick enough that it covers the water surface it might not work as well as the liquid Imazapyr.

Al, I agree with your approach.

When should I start treating it. There are very few surface leaves right now but it will warm up in a few weeks. Should I start as soon as the leaves start showing or let them grow a bit then start. I don’t want to let them get back to where they were last year before starting treatments.

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.

Thanks, that is what I will do.

Fighting the same situation on a 12 acre lake in NC. Did a huge amount of hand work last year with some success. Also tried the Aquacide Pellets which in my experience did little or nothing.

Questions on the Ecomazapyr for the experts out there:

1). Our dogs and some swim in the lake pretty much daily. Any safety concerns?

2). Maybe I am just missing it or too inexperienced with all of this, but looking over this thread I guess I do not really understand what ratio to mix. For example, if I am spraying round up on my lawn I buy the concentrate and use X tablespoons per gallon to achieve the desired concentration in my sprayer. What ratio should I use with a large back pack sprayer and the Ecomazapyr?

My simple answer is to read the label on the bottle. It will tell you how many ounces of herbicide to use per gallons of water to cover "x" amount of pond surface area.

This is what I posted in this same thread above: 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.

I would also mix in some pond dye to the tank mix so you can see where you sprayed and so you don't over or under spray an area.

Go here: https://alligare.com/products/ecomazapyr-2-sl/, scroll down and click on the green label tab. You will want to read page 8 and 9.

As for the pets, if applied per the label, there are no restrictions for livestock.

If using a backpack sprayer, you will have to carefully figure out how many sq. ft. of the pond surface you can cover with the amount of herbicide you put in the back pack sprayer.

I was up at the property this past weekend and decided it was time to spray. I put just water and pond color in my sprayer as suggested in this post and sprayed about 1/3 of the watershield for a test. That worked out well because it showed that I couldn't reach some spots from the bank that were farther out. Mixed the chemical and pond dye and sprayed what I could from the bank then got in the boat and sprayed the outer part.

How long does it take to start seeing results? I did notice that the small test area I sprayed last fall has not grown back. Maybe I got fooled thinking it was the cold that killed it off.

After this dies off good I will spray the 1/3 where it is the thickest.

You should see them turning color within a week or so.

Ok thanks, I will keep a lookout for that.

Checked the watershield yesterday but didn’t see any color change yet. It’s been 1 week since I sprayed, hope to see something next weekend.

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

I was out at the property this past weekend, I am not 100% sure yet but I may be starting to see some color change. I will check again next trip. Looks like rain most of the week so it won't be until next weekend so that will be 3 weeks since spraying.

I thought I would see a bigger difference after 2 weeks to be honest but will give it more time.

i found that Navigate worked slowly until the water temp got into 70s - then it worked all over the pond - even where I hadn't placed it.

Well the watershield is slowly dying off where I originally sprayed. I went ahead and sprayed the next 1/3 of the pond but added a bit more chemical than the last time. I re-sprayed what was left in the first area just for good measure. I took some before pictures this time so I can really tell how effective it is. I should have done that the last time I sprayed but didn’t think about it.

Glad to hear that! Please keep us posted on the progress.

Will do, It seems to die off pretty slow so that is a good thing as it won’t decompose too fast and rob O2 from the pond.

The watershield is dying off nicely and our pond is starting to look good again. I will try to resize some before and after pictures when I get a chance and post them in this thread. I still have a bit more to spray but will do it in small sections as it dies since we are already in the 90’s down here and don’t want to have any O2 issues. Thanks for the help, I am feeling a lot better about it now. I have a little over half of it done now and will continue until it’s all gone.

Great, glad all's going well. Watershield can be a tuff one.

Yep it seems to be going well so far. I resized some before and after pictures but the site won’t let me post them for some reason. I’ll try on the computer when I get home.

I tried to post some before and after photos but the file type isn’t supported. My image resize app saves them as a jpeg file but the site wants it as a jpg file 🤷🏻‍♂️

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.

I'm going to let more of my water shield grow back as I'm finding it holds the bass this time of year.

Pulling a creature type soft plastic along the top of the watershield along the bank has been about the only way to catch bass while the sun is bright.

A little bit is good, even a few "islands" of it around the pond gives them edges and cover to hunt from. Too much makes the fishing hard.

The only way to successfully fish it is to horse the bass out or bring the boat into the weeds and hoist them out. It is exciting tho to see them bash the lures tho...

Is Imazapyr your preferred herbicide for watershield? I used diquat as some of the stuff we buy for the farm was also labeled for aquatic use as well. It did a number on them but many came back. They've been around for years so I suspect it would take several treatments to burn them out with it.

Diquat is not a systemic herbicide it just mostly kills the top vegetation on most weeds and watershield thus it just kills the tops and leaves the roots intact thus their regrowth.

So basically anything would be better than it for watershield? lol

Not all aquatic herbicides have the mode of action systemic.

My earlier sprayings this past spring has it knocked back pretty good on the parts I treated. However I am seeing some small areas of regrowth in those areas again. Now that it’s starting to cool off I am getting ready to treat the rest of the pond. I will also treat the regrowth areas as well.

Next year I will spot treat anything that regrows throughout the year and hopefully keep it all knocked down. I should have it all under control by next summer.

Thanks to everyone that gave me advice along the way.

8upbowhunter