- Flumigard Herbicide - Fast-Acting Flumioxazin Weed Killer for Rapid Control of Aquatic Algae and Terrestrial Weeds in Forestry, Aquatic, and Bare-Ground Sites - Granules -1lb

We have a 20 year old 1/4 acre oval shaped pond located in southern Louisiana. The pond has several types of panfish, catfish, frogs, and turtles, as well as gets visited by plenty of wildlife. When we fist dug the pond I made the mistake of using duckweed to help clear the clay from the water. The duckweed worked and the water cleared up quickly. I then used diquat herbicide to kill the duckweed. This worked but we have never been able to completely kill off the duckweed. Over the twenty years, we have probably gone through several gallons of diquat to control the duckweed, along with blue dye to control the submerged weeds, but recently we had lost a lot of the ponds shade trees as a result of Hurricane IDA. The pond now gets sunlight all day which has made the duckweed uncontrollable and also increased the amount of what looks like Filamentous algae. The algae was forming submerged mats which the diquat had no effect on. After much internet research and out of desperation, we figured we had to try something else, but had to make sure it would not kill the fish or wildlife. We ordered the Flumigard Herbicide. According to the directions, we estimated we would need to use 1/2 of the container (powder) mixed with water in a 1 1/2 gallon hand sprayer. We also added 3 ounces diquat and a few ounces of 80% herbicide surfactant. We sprayed the pond as evenly as possible in May with 75 to 85 degree weather. We also added the normal 8 ounces of blue dye that we routinely add to the pond. Results were slow but after one week all of the duckweed was gone and the mats of algae were staring to show signs of reduction and breaking up. It has to be noted that May 2023 was a dry month in Louisiana. Dry like drought stage. So the pond was not getting any rain water. After two weeks, the mats were gone and we were able to remove some of the remaining clumps with a net. At three weeks the pond was really looking the best it had in a long time, but then we had five inches of rain. The pond turned green with all of the new rain water. You have to be careful with this product as the instructions said to not add any additional product for a minimum of 28 days. Instead of adding any herbicides, we added an additional 8 ounces of blue dye. POND LOOKS AWESOME. We are saving the other half of the container and am monitoring the algae growth. If it starts to show an increase, we will try the less expensive option of diquat with surfactant. As we added both herbicides at the same time, it is hard to say what actually did the trick other than the combination described above worked for us. Highly recommend. 07/10/23 UPDATE: Well its been about six weeks since out initial application describe above. It has been HOT, HOT, HOT with a couple downpours over the last few weeks. Pond was looking great until a couple days ago. We have a new growth on the surface which looks like pond scum or some kind of surface algae bloom. NO DUCKWEED and NO SUBMERGED weeds though. I used the other half of the Flumigard, 2 0z. 80% Surfactant, and 2 oz. Diquat in our 1 1/2 gallon hand sprayer. As soon as the herbicide it the surface, the scum changed from a bright green to a dark green and starting breaking up. Hopefully this does the trick and does not kill the fish. I am happy to see that the duckweed has not returned. It has been scorching hot (90 to 100 degrees) everyday with full sun beating on the pond. I have not checked the water temperature lately, but I would think it has to be in the mid to upper 80s. With all that said, I would say the product is doing what it is supposed to do, which is controlling the weeds.

This stuff is great. It kills weeds and grasses that want to grow on the court. If I add a bottle of Dawn detergent, or another surfactant it works wonders removing duckweed, watermeal, and other floating lake weeds. It has completely cleared our 2 acre cypress sink of duckweed, and watermeal, and it is now shown as a waterbody on google maps/earth. It has removed most of the duckweed and a lot of floating grasses from the lake so that my boat ramp and channel are now open and connected to the rest of the channels in Lake Iamonia which is huge. It makes the property more beautiful, more open to fish and wildlife, makes the property more valuable, allows for oxygen and sunlight to reach into the water. And allows me to boat around and enjoy life. It is the best for the price. Thank you Flumigard!

Updating my review… I applied this in the beginning of august and now in September everything is DEAD. Well let me rephrase that…all the undesirable weeds are DEAD. The fish, turtles and frogs couldn’t be happier. I had a major duckweed problem across the entire pond and maybe 1/3 was covered in a small leaf lily plant. I applied this by hand tossing it out onto the lilies from the shore until the plastic jar was empty. I probably covered 1/8 to a max of 1/4 of the surface. There isn’t much in a package let’s be honest. The first week it killed the lilies in the areas I tossed it. Then the duckweed started to go. Eventually it all went. Here we are in the beginning of September and there isn’t a piece of duckweed or lily alive anywhere. It’s pretty amazing stuff. There is no aeration or fountain moving any water either. This stuff somehow on its own made it’s way through the water killing every weed in its path taking no prisoners.

This stuff works great for my pond for getting rid of duckweed and is easy to use. I fill a 5 gallon bucket 1/3 the way with pond water, sprinkle ~1/8 lb of flumigard in, let it dissolve in the water by spinning the bucket side to side by the handle, and then toss the mixture towards my fountain. I do this 4 times (so ~1/2 lb used) for my size pond (~1/4 acre) for lots of duckweed, and 2 times for low amounts of duckweed. Just wish it was cheaper as it does take quite a bit to be effective.

If you have a pond that has green stuff on top of it, then this is what you need! I tried numerous things before I bought this I even put in a pond fountain thinking it would clear up my pond but no luck. I decided to give this a try and it a was a game changer! My pond went from a green film all over the top of it to a clear pond that is absolutely gorgeous! It did take a couple of applications to completely clear it and now I just add as needed to maintain it. I highly recommend it.

this helped calm down our duckweed situation.

Last year our pond was infected, for the first time, with watermeal. We spent about $1000 on fluridone, and that did nothing except empty our pocketbook. We were so down about losing our pond to this stuff and did not know what to do. I talked to an "expert" in the field, and they said, "if you use this stuff it will kill your fish!" Finally, out of desperation, I went ahead and used it anyway, and oh my gosh, I'm so glad I did. I used just under one pound on a 3/4 acre pond with a couple squirts of Dawn dish detergent for a surfactant. First three days....nothing. Then, day four, we noticed the duck weed was turning white, and the watermeal was turning a ligher color. Day eight, and oh my gosh!!!! Our pond is 90 percent clear, and what's left is white and on it's last legs. We are getting our pond back!! we are jumping for joy! Yeah, by all means, this is THE 'magic bullet'!!

I used as directed on Duckweed last year and it worked perfectly. I used as directed this year on duckweed and after 30 days it isn't working. Not sure why?