Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants weeds going nuts....

So this spring I had a little FA and was able to keep up by raking it out. The water level in my ground water pond has stayed unusually high in June, even killed a foot or more of grass around the edge, although now that the water has slowly dropped again some of that grass is coming back. During June I have had slow increase in FA and I can continue to rake that if needed. I put about 20 tilapia in as an experiment to see if they had any noticable difference. I can deal with FA, but the weed explosion is a different matter.

The water is exceptionally clear, the weeds start at about depth of 4 feet and the 2' closest to shore is large floating mats and rooted plants that are tall enough to have the majority of the plant floating. I can try to rake but it is enough mass that I almost would need a large chain dragged on the bottom, a box spring dragged through etc. The pond is small enough that I could probably do that although I would worry a bit about my aerator and bottom line would want to be sure to work around this or remove it first.

Can someone give advice on the weed? It seems to be only 1 type that is growing so avidly. If I go the chemical route what is preferred?

Only fish are tilapia, FHM and GSH, Depth in middle now is 7-8', fluctuates a foot or so depending on water table. Aerator running 12 hours overnight every night.

I don't feed the fish, I don't fertilize although I'm sure some lawn fertilizer does wash into the pond.

Every spring I have lots of turtles, and a month ago they would float on top of the mats of FA, but lately I haven't seen them, last night only saw one in the middle of the pond.

Where do the minnows hide, under the vegetation? I haven't seen them much but maybe the dense weeds on the edge are the problem as well. The pallets I put in are engulfed in weeds as well.

The pond is maybe 25 yrs old, but was drained and redug spring of 2012, no vegetation most of summer of 2012, only a bit of weeds all through summer of 2013. Big time growth this summer.

Pictures:

pictures aren't working, I'm going to try to see what I did wrong..

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got it fixed now

Looks like Eurasian Milfoil in my opinion.

Somehow, someway you got Eurasian Water Milfoil (EWM) in the pond. Raking it won't help - it spreads by seeds or by pieces of the plant breaking off and rooting. It's an invasive species. There are products on the market that kill it, but the best that I've found (although it isn't cheap) is Fluridone (Sonar AS). Navigate or Aquathol Super K also works, but you can use Fluridone and use a low enough dose so that only EWM is affected and not impact the other underwater plants in the pond. Treat early enough in the year so that it's killed before it sets seeds, or it'll show up again next year. By the amount that you have in the picture, it didn't just show up this year.

I would plan on treating it both this year and next year, as soon as the water started to warm up in the spring and it's actively growing. It's already set seeds this year, at least down here.

I had a fair amount of EWM in my pond pond last year. I never did treat it and now I can't find any trace of it at all.

I'm researching the chemicals out there. I'm finding a diquat chemical in 8% and 37% solution liquid, local farm/ranch supply stores carry it.

I looked at sonar, navigate granules and aquathol. I can't easily get in my pond right now to spread a liquid evenly. Throwing granules from shore would be easiest. Does that mean aquathol or navigate? The diquat says you can spray on the weeds from shore which would work well for me too.

So it is late in the season but OK to treat now and then next spring? I have to rake out the dead weeds too somehow?

You say using fluridone at low enough dose to protect other plants, what dose/mixture do you recommend?

Thanks!

To treat the pond, you have to calculate the gallons of water in it.

So, you have to know 2 things minimum, 3 things is best.

1) Surface area
2) Maximum depth
3) Many depth readings to more accurately calculate the average depth, and then the corresponding volume of water.

If you know 1 and 2, take 1 and half of 2 to get average volume of water.

1 acre foot of water (one surface acre, one foot deep) is 325,851 gallons.

i.e. 1/2 surface acre, max depth 10' = 1/4 2.5 ac/ft of water.

Fluridone can be sprayed into the pond with a coarse stream, instead of a fine mist, but it's not the recommended way to do it.

Weeds don't need to be raked out, but if using a contact herbicide, only treat 1/2 the pond at a time to prevent an O2 crash when they die and start to decompose. Fluridone kills slower, so the "die all at once" scenario and resulting O2 crash usually doesn't happen.

EWM is susceptible to Fluridone at levels of 7-10 PPB. i.e. roughly 1 fl. oz of Sonar A.S. per ac/ft of water.

Thanks Esshup, a lot of good advise and experience in that one reply!

I found this calculator online where you input length and width if you have a rectangular or mostly rectangular pond and average depth. My pond is oval, 200' by 100' and currently depth in middle is probably 6-7' and so using 3' as average depth I get .46 surface area acres and 1.46 acre feet.

However if I use a planometer tool and outline the surface of my pond on an aerial map I get closer to .3 surface area acres and in the calculator then acre feet would be .94 acre feet.

Is this right? You say 1/2 surface acre 10' deep would be only 1/4 acre feet and my math says my smaller, shallower pond is 4 times that much?

Or is my average depth with a gradual gentle slope even to the deepest part the issue and my average depth might be closer to 2 feet?

I'd like to get the acre feet nailed down to use the right amount of sonar (wow is it really nearly $3000 a gallon? that has to be more expensive by the gallon than printer ink or white out!)

If I only have to pu in 1/2 oz or 1/4 oz in my pond, could I just put that amount right in my aerator plume (from a boat) and let it spread that way?

.3 surface acres x 3' average depth .3x3=0.9 acre feet of water)

Canyon, I'm sending you a PM.

Aquathol Super K @ 3 ppm. Apply around the perimeter on the weeds and allow the product (active ingredient endothall) to equilibrate across the pond. This will extend the exposure time and aid with killing the milfoil. I'd go ahead and treat to prevent the plant from putting down any more seed this season. Based on your calculations you'd need about 13 lbs of product. New packages are shipping and come in 20 lb bags. You don't have enough coverage of weeds in the pond to be worried about DO issues.

I think I have the same thing in my SW Ohio pond. Here's a couple of pics. I "think" I have about 12 acre feet of water. My pond is 2 acres and I'm guessing about 7' average debth. It's just a foot or two in some places and close to 23' at it's deepest. So is the Aquathol Super K the cheapest way to address this or the Sonar?

You can buy sonar in quarts. Plan on treating it again next year or the 2nd year. Seeds which have been produced this year will lie dormant and sprout next year and thereafter. You will eventually need to retreat due to return of milfoil or some other weed. Do the math for your costs and amount of each herbicide needed. Aquathol superK is a granular and SonarAS is a liquid.

I don't like that math one bit! 12 acre feet is thousands of dollars if applied like they recommend. I may use the Diquat and Copper Sulfate mix first on one area and see if that gives the desired results.

A large pond is great until it comes to buying herbicides for weed control.

I raked mine daily for most of the year, and finally got it under control. It was a lot of work and I hated it. But I cleared most of it.

I've been raking every day for the last 4 days. The Home Depot rake works excellent when you put a rope on the handle.

I can rake out about 6 foot and then could throw the rake out with a rope. But i was wondering about making a 10' long 'throwing tube' to speed up the process.

I was thinking of making a hybrid between the 'prickly rope' that is featured on this forum and is a great idea for large areas of floating leaves and lightweight weeds. However, mats of FA get heavy, the zip ties pointing down may or may not be able to pull them in...

I was thinking of taking a 10' piece of 3/4" or 1" PVC. Metal tines might be the best but I'm not sure how to easily fabricate and don't want to add a lot of weight. I have a roll of very stiff, thick wall irrigation pipe. It is called funny pipe or swing pipe. It is not the thin walled smooth stuff that you can buy at big box stores, it comes from an irrigatino supply place. It has a textured outside and is thicker walled, more stiff and takes the fittings so tightly that the pros don't need clamps to hold the plastic sprinkler ends in. I have a bunch left and thought it might hold its curved shape better and may grip the mats of algae and pull them in without bending back and letting go.

I could use small flat head screws to screw them in to the PVC pipe? Not sure if PVC cement would work as I think the plastic properties of the swing pipe is different.

Then a rope on each end of the PVC (or could thread rope all the way through the PVC pipe) and throw out and pull it back in.

If it works well I may thread the rope through the PVC pipe, and then put 2 sections together with a short say 1 foot section in the middle to allow it to be pulled like an upside down 'V' back to shore.

If I need flotation I can add floats or a pool noodle.

The mats get heavy so once they are by shore I may have to still take the landscape rake and rake them up and out on to the shore to dry.

I have a trailer load of dry mats of FA that I dumped in the back woods. That stuff is woven together like steel, my mower can't chop them up, it just kills the engine as the blade wraps in it. As it dries out it doesn't seem to be any easier to work with.

I'm open to other ideas...

I just put 20+ feet of rope through a hole I drilled in the handle of the Home Depot aluminum rake. I throw it out there quite a ways. It pulls in so much that by the time it's to shore I don't want it any heavier or I wouldn't be able to pull it out and lift it over my garden trailer to dump it off the rake.

Some stuff does break off and floats to the surface and actually "mats" together. I use a section of foam noodle zip tied to the rake to make if float for scooping up the top mats. I wait a day till it mats.

For some reason I don't have algae this year, but in the past years, I used a HD pool leaf skimmer scoop net on it's telescoping pole. It worked really well. In just a few seconds you could fill the scoop with algae and pull it in. Dumping it over my garden trailer took 1 second. Very quick to use. Again, if it was any bigger it would be difficult to use because it would be too heavy.

Milfoil grows from any pieces that are broken off of the plant too, even pieces as small as 1" long. So, if you are raking milfoil, and not getting all the pieces all you are doing are making more plants.

If you think your pond is expensive to treat, I have a Homeowners association that has a 18.8 acre pond, a 4.5 acre pond, a 2 ac pond and a 1 ac pond..........

I'm raking to get as much of the bio-mass out of there as I can before I treat it so I don't get so much dead crap at the bottom of the pond.

Milfoil tends to clear the water which then allows it to grow deeper over time, think of it as a feedback loop. If one can manage the water clarity it will keep milfoil from getting out of hand.

I had milfoil in my pond this spring but we had two gully washer rains three weeks apart that muddied up my pond long enough to kill all of the milfoil.

Esshup
Having a new pond what plants would you want in it or none at all?

Pat

My pond has pretty steep banks so I would love to get milfoil but my pond drains to a creek that eventually empties into the Shanendoah River so introducing milfoil would get me in all sorts of trouble. It really is a great plant for bass, they love the stuff!

What, you don't have fun like this in your pond/swamp?

I'm in the middle of replacing the suction and discharge lines of my fountain/watering pump, I'm not snorkeling in that mess.

In a new pond I'd look into hardy lilies (of a color that you like, and a species that grows in the water depth where you want them growing) Pickerel Weed, Arrowhead, Blue Flag Iris.

Plants will show up on their own. Then you'll have to deal with them if they start getting out of hand.