Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Coontail elimination in 4 acre feet farm pond

My pond is .5 acre with about 7 foot average depth. 4 acre feet or under. I am a 72 year old widow, some what active. Last year my pond was covered by coontail. I manually harvested it by pulling out by clumps into a canoe. Put oar into water, swirled it until gathered a large clump then pulled into canoe again and again. It looked much better. So now I am concerned about the growth again. I really don't want to do that again. I have been looking into fluridone. Expensive.

Questions:
1. What effect should the self harvesting have on the growth this year.
2. Should I wait to see what happens this year before treating.
3. Is Fluridone overkill?
4. Something better?
5. I have been looking at Sonar RTU. Any advise on this product or any recommendations would be sincerely appreciated. Sonar RTU sounds like the simplest but can't find many reviews on results.
My pond has no outlets. Basically self contained. 100 year old pond probably. Some fish but don't use it for much.
I like the long acting possibility of Fluidone but price could be an issue.
Also have looked at:
Diquat (Rated: Excellent)
Endothall (Rated: Excellent)
Fluridone (Rated: Excellent)
The quick acting Diquat and Endothall a lot of work. Multiple appilcations. Which is harder for me. I have a 15 gal sprayer and the spray doesn't reach to the middle of my pond which is about 100 feet wide.
I have been researching this for hours and hours over the years and hoping for some easy resolutions.
Thank you before hand.
Any help, suggestions appreciated.

Welcome to the forum. The downside to coontail is that it is resistant to herbicides and it's one of the harder plants to kill, so whatever you use will also kill any plants in the pond that are less susceptible to herbicides.

Since your pond is old, it has a lot of residual nutrients in it. Eliminating all the aquatic weeds in the pond will most likely create a large filamentous algae bloom.

Triploid Grass Carp are an option, but they probably won't do much this year. The recommended amount of TGC to stock is between 7 to 14 per surface acre of vegetation that you want controlled.

Sonar AS is actually cheaper per ounce of active ingredient. It doesn't really have a shelf life, so using part of a bottle will leave some for the subsequent years. I know some say 2 years but I have had it for 5 years and I see no degradation in effectiveness.

A rough way to calculate average water depth is take max depth and divide by 2. To get a rough idea of acre foot, take that sum and multiply it by the surface area of the pond. If your calculations are correct and you have 4 acre feet of water you will need 27 fl. oz of Sonar AS because you need a 90 Parts per Billion dosage over 30-45 days to kill coontail.

Sonar RTU has 3.79% Fluridone. Sonar AS has 41.7% Fluridone. Sonar AS is a one and done treatment (per year - you have a good seed bed in the bottom of the pond and no herbicide kills seeds). You will most likely have to treat every year for a number of years in a row to kill the plants that germinate from the seeds when using a fluridone product. You want to kill the plants this year before they set seeds. Coontail typically dies off during the winter here in the northern part of the USA and starts the next year from seeds. It will also propagate during the year from plant fragments.

When you look at the dosage rates for Sonar RTU, you have to use the rate for Watermeal to kill Coontail. Watermeal also needs the 90 PPB dosage. So the recommended Sonar RTU amount you will need to use for your pond is 6 quarts or 1.5 gallons.

Since your pond is only 0.5 acre, I would recommend using Diquat and Cutrine Plus liquid mixed together. Yes, it will take multiple applications. It is a contact herbicide, so you don't want to treat the whole pond at once, I would only treat 1/2 the pond at one time to prevent an O2 crash due to many of the plants dying at once.

It's not important that you reach the center of the pond, spraying out in a solid stream from the shoreline should work - you should be able to spray 20-25 feet out from shore. Endothall works good but it is toxic to fish if used incorrectly. You have to apply it from shoreline out so you don't trap fish up against the shoreline with nowhere to go. If using the Diquat mixture, I'd also mix in 1 fl. oz. of surfactant per tank mix - 15 fl ox. for your 15 gallon tank sprayer. I have a Cygnet distributor near me, so I use Cygnet Plus for a surfactant.

Oops, I almost forgot. Re: self harvesting. It is hard to tell because of the method of self harvesting. Since the plants grow from plant fragments, it all depends on how many fragments were generated. If many fragments, it could make the weed problem this year worse because of having more plants = more seeds to germinate this year.

If you are going to self harvest, I would use a net to minimize the amount of plant fragments, but as you found out it is very labor intensive. If you are going to use a herbicide, go buy a swimming pool thermometer. Start the treatments when the water temperature (not air temperature) is 60-65 degrees and climbing. That is when Coontail starts growing the fastest.

Thank you so much. Great detailed explanation.

Could you advise me on the amounts of Water, Diquat, Cutrine plus and surfactant in my 15 gal sprayer. I want to use all the solution in the sprayer to treat 1/2 of pond at a time.

I get a little confused about ratios. I have, in the past, just used the ratios on label, filled up the tank but just spray treated pond not really figuring the area. My concern has always been that I am not getting enough chemical into the pond or too much.
Ideally the ratios I put in sprayer would allow me to use all of the solution per 1/2 area.

Hope you understand.

So sorry if asking silly question. I am a woman and we tend to over think everything. LOL

Thank you again for any help.

WPOwner Are you positive that the plant is coontail? I had a course of Aquatic Vascular Plants in college. Coontail looks very similar to a couple other plant species. Has your identification been confirmed by some one with experience?.

Ponds are expensive to properly manage. Then old, old ponds have had many years of each year accumulating more nutrients to collect and feed more algae / weed problems. Many years of accumulations result in many more old age pond problems as you are now experiencing. Once dead organics releasing nutrients that feed plants are in the pond how do they get out???? Usually the nutrients don't get out, the pond just keeps collecting more nutrients. IMO for a 100 year old pond, look into Mucksuckers in central OH. .

Funny. I had them out last year to do the shallow end of my swimming pond. We will see if it was worth it this year. Quite expensive.

The exact amount of Water/Diquat/Cutrine Plus/Surfacant to tell you to use is difficult to explain because of the unknown - i.e. the operator. The amount used is also based on the amount of plants in that area to be treated. Since I am not there looking at it (and I can't give you an answer from a picture either) I can't tell you exactly how much to use. I can give you some advice though.

Also remember that you said that you cannot spray the whole pond because your sprayer won't reach out to the center of the pond. (see below why that is a bad idea anyway)

First off, all that I say is based on a correct weed ID like Bill said. Without a 100% correct plant ID all bets are off. If I have a plant ID question and I can't send a picture to any of my resources, I will hop on the Texas A&M website and start going through all the information there. TAMU Aquaplant

Using a contact herbicide, you don't want to treat the whole pond at once. Too many plants will die at once, then when they decompose, that decomposition causes a tremendous oxygen demand on the pond. That O2 demand might be more than what is in the pond for fish to survive. The way I look at O2 in a pond is that the higher the life form, the more O2 it needs. For example, bacteria can survive on less O2 than fish. Fish need roughly 5 mg/l to reliably survive although they can get by on less, depending on the species of fish. Yellow Perch are stressed when O2 levels are less than 3 mg/l. Bluegill start showing sluggish behavior around 4 mg/l.

Bill, please edit this if these numbers are wrong.

Aerobic bacteria really slows down at 2 mg/l. So, aerobic bacteria will most likely survive levels of O2 that would kill fish.

Getting back to your question. I cannot stress enough that you have to read and understand the herbicide label. Take into consideration all the warnings and caveats. More is NOT better. Plants can go into shock if too much herbicide is used, and not "suck it in" to kill the plant. That is especially true with systemic herbicides where the herbicide is translocated to the roots to kill the plant, roots and all. Contact herbicides basically just give the plant a haircut and the plants can re-grow from the roots if there are enough energy stores in that root system. i.e. Cattails and water lilies. Now if you kill the plant re-growth multiple times in a growing season you might be able to kill the plant roots and all with a contact herbicide, but it's better to use a systemic in that scenario. Coontail is not a rooted plant, so a contact herbicide will work just fine.

When using a herbicide to spray submerged plants in a pond, you have to keep the following in mind: The water in the tank is just there to ensure that you get even, optimum coverage over the area that you are treating. It does NOTHING more than that.

Surfactant - 1 fl. oz per gallon of tank mix. If you are using a 15 gallon sprayer and fill it up, put in 15 fl oz of surfactant. If you are only filling it up half way, use 7-8 fluid ounces of surfactant. That's pretty much a general rule that I use. I might use a *little bit* more per tank if there is a LOT of vegetation or algae in the area that I am treating.

Cutrine Plus Liquid - READ THE LABEL. It has rates listed on the label on how much to use for a certain area based on how much algae there is in that area that is to be treated. Use the amount that is listed in the label in Table 1. Cutrine Plus Liquid Label

Diquat - READ THE LABEL. It has rates listed on the label on how much to sue for a certain area based on how dense the weed growth is. Please read all the safety precautions on PPE gear that is in the label, then skip to page (I believe) 12 and 13 for the amount to use. Diquat Label

You have to remember that these labels are talking about how much of the concentrated herbicide/algaecide to use in the tank to cover the area that is listed in the chart on the tank. The amount of water that you use makes no difference PROVIDING you use enough water to ensure even coverage over the whole area.

If you don't spray a lot, you probably don't know how much liquid you will need to completely and evenly cover the area that you want to treat. That's perfectly normal and OK. What I would suggest to do is to fill the tank sprayer only with water and do a test run. Do it more than once if needed. There is no harm in using less of the herbicide/algaecide in the tank and having to spray the same area 2x or 3x to get even coverage over that area. Spraying a pond is different than spraying on land. It doesn't matter if you use too much water as long as you get the correct amount of herbicide sprayed on the correct area (or correct ac/ft of water). On land, using too much water can result in washing the herbicide off of the plant and onto the ground where it most likely won't work.

As a tip, I like to put pond dye in the sprayer so I can see that I am getting a good even coverage (this applies more to emergent and floating plants/algae that I am spraying than to spraying a certain area of pond water). When spraying those.I want to spray to the point right before the herbicide runs off the plant. Having dye in the spray allows me to see the coverage I am getting. The amount of dye to use depends on the strength of dye, the amount of liquid in the spray tank and the color of the vegetation that I am spraying.

Piggy backing on the topic... I have a stone point and a dock. Both jut out into the lake. We like to swim around the dock, and fish around both. I'd like to get rid of the coontail around them, but don't want to discourage fish since fishing is the primary use. Any of these chemicals that I should avoid? Any of the them specifically hard on fish or cause them to avoid an area?

Everything listed is rated for use in ponds. The Amine salt formulation of Endothall is hard on fish if applied incorrectly. (Hydrothol 191).

As always, read the label and follow it's directions. Not doing so is a waste of money and can kill fish. Case in point. A few years ago a customer who had a 1 ac swimming pond that had 5#+ Bass, large catfish, etc. in it wanted to purchase Cutrine Plus Liquid and Granular to kill the FA in his pond. He wanted enough to treat the pond for the whole year. I ran the calculations for him, told him to follow the label instructions and that this was enough for 12 treatments, roughly 2 weeks apart.

He called me a week later and said that he killed all his fish. After talking to him it seems that my spoken instructions went in one ear and out the other. He didn't read the labels either. He said that if a little is OK, a lot should be better, right? and that he didn't want to treat the pond every 2 weeks. So he put ALL of the Cutrine Plus for the whole year, both liquid and granular in the pond at one time.

I'm always pretty careful when I spray on land. Read labels and do my research. Just curious if some of these chemicals can create a spot that fish just don't like? Not killing them and not repelling them are different things.

What ever muck and sludge they removed had to be beneficial to some degree for getting accumulated organic nutrients. How much benefit depends of the total amount of accumulated sludge in the pond. The amount of new plant growth will depend on the amount of remaining nutrient basis still in the pond.

Remember killing submerged or floating plants does nothing to reduce the amount of total nutrients in the pond. It basically just blows ones nose when having a head cold; very temporary relief. The Virus infection has to be eliminated before the runny nose and congestion problems are eliminated. Nutrient level has to be measurably reduced before amount of plant growth is significantly reduced. A 100 year old pond at this point in its life is a good candidate for a complete rebuilding of the pond.

I am still NOT convinced the weed problem is coontail and that the 100yr old pond has an average depth of 7ft and 4 acft of water. Maybe yes this was true as a new pond, but now not after 100 years. Normal ponds without bottom aeration accumulate one inch of bottom muck and slop each year. 100 " = 6ft to 8ft shallower. Before I would be spending good money on herbicides, I would make darn sure of the plant identification AND maximum and average pond depths.
Okay I just called and talked to the project manager of Mucksuckers. He said the pond as he remembered it was only about 0.25 ac, somewhat horseshoe shaped and around 7 ft max depth. By all means this should be fully verified before any chemical calculations and volumes are added to kill the weeds; PLUS verify the weeds are really coontail. If one does not know the structural details of submerged vegetation Coontail (Ceratophyllum) can be easily confused with Chara, the milfoils (Myriophyllum), bladerworts (Utricularia), the naiads (Najas) and even common waterweed Elodea.

If I had an address of the pond I could look the pond up on one of the satellite measuring tools and measure it to verify the pond size. You can send me or esshup a Private Message.

The only time I have seen aquatic herbicides and/or algaecides affect fish (make them leave an area for any length of time) was when the company that had the contract to kill weeds at the local public lake sprayed for weeds and algae when the BG were bedding. They left the beds and didn't come back until the following month. I don't know if they killed the eggs or what happened. They said they sprayed a mixture of Weedtrine D and Copper Sulfate.

That's the kind of info I was curious about. If you've only seen it happen once then I'm betting the odds are favorable for me to spray with no side effects.

Thanks for the info!

Thanks for response.

The pond those guys worked on was my 36 year old swimming pond. My back pond is the one that had the coontail.
I did have someone from Ohio extension offices verify. Believe me, I pulled probably a thousand pounds of the stuff. A lot anyway!

Now on the subject of depth. Depends if you go thru the muck to solid base. If to the muck maybe not. Should I only figure to the muck layer?

Correct, only to the muck layer where the "clear" water stops.

esshup has it correct. For the coontail you should only add enough chemical to treat the water above the sediment layer. Once you get it killed ask OSU extension about putting in enough grass carp to keep it fairly clean. Don't put in enough grass carp to eat it all or the coontail biomass will be replaced by filamentous algae. You always need something in the pond to be consuming all the recycling nutrients. Nature demands that something will feed and grow with all those accumulated nutrients contained and trapped in the 36 yr old pond basin. Pond is very enriched as is evidenced by the amount of coontail that currently grows each year in the pond.

^^^ All great points!

My coontail doesn't grow deeper than 8ft, so a lot of the basin remains open. And it seems crawdads love to eat the stuff. I like to topwater fish over the coontail in the summer. Almost every bass I catch is full of crawdads. That has to be a great food source for them.

Topwater fishing in late summer is a blast.