Q: I think I have duckweed and watermeal. It’s taking over my pond! I can’t seem to get ahead of it! What do I do?
- Several Customers
A: Duckweed and watermeal are very prolific growers and can cover a pond before you know it. When covering a pond it can look like algae, but up close you can see it’s not (see pictures on the left). You can try to rake the duckweed and watermeal off the pond’s surface but more will be back within the week. The absolute best way to get rid of duckweed and watermeal is to use a product called WhiteCap. WhiteCap works by inhibiting the weed’s ability to produce carotene. Without this ability, chlorophyll is rapidly degraded by sunlight and the weeds die. The only water use restriction is a 30 day irrigation restriction.
WhiteCap will also get rid of many other submerged weeds in the pond and will produce season-long results in as little as 30-45 days.
For more information on Whitecap and the aquatic weeds it will control, click here.
Filed under: Duckweed, Pond & Lake, Watermeal | Tagged: controlling duckweed, controlling watermeal, Duckweed, duckweed control, kill duckweed, kill watermeal, sonar, Watermeal, watermeal control, whitecap. white cap
I have tried everything. Is there not any home remedy or something that will KILL watermeal for good. I do not want to control it, I want to kill it. I have used reward, sonar, diquat, etc. draining the pond, nothing has helped…any suggestions? I am desperate.
Freddie Fay,
I totally feel your pain when it comes to watermeal. This is an extremely fast growing and hard to kill aquatic plant. The absolute best way to treat watermeal is to use WhiteCap. When using the products you mentioned, was there any die off at all? If not, I guess we should go back and look at first the size of your pond as well as the depth of your pond. The other thing you can do is to send us a weed sample as well, just to make sure we are dealing with watermeal and not another aquatic plan or a form of pollen or oil slick. You can send a sample to: The Pond Guy, ATTN: Weed ID, 6135 King Road, Marine City, MI 48039. Include your pond information as well and we can see what we can do to help you.
Hi Pond guy — I do have a bad case of watermeal (it was sent in for analysis) and would like to use Whitecap. It is now late March and I was wondering if it is too early to apply. Should I wait until I see the first signs? I have a spring-fed pond in Brighton, MI, approx. 100×200 feet.
Thanks.
Cheryl B,
Great question! During the Spring, you can use WhiteCap approximately 2 to 3 weeks before you would normally see the watermeal floating on your pond’s surface. If you can treat it a couple weeks earlier, you will have a better shot at keeping it bay. To give you a time frame, you would probably see some watermeal forming on your pond’s surface mid-April to Early May. I would apply WhiteCap around mid-April for best results.
Again, great question, hope this helps. I apologize for the late reply.
Along these same lines – we treated our 1.5 acre pond (has small island in middle) for duckweed this spring – used what Sonar recommended – their new product (pour in pond rather than spray). Worked well – then watermeal took over. We have never had that before. At this point it is covering the entire pond except the 20′ spot where our bubbler is for our fish.
My question – I know you recommend WhiteCap – is it too late to apply it since it is starting Fall now? When should be apply it in the Spring. Lastly, will it also kill duckweed or should we use the Sonar product again next Spring?
Thanks much –
C
Hi Cindy, Whitecap has the same active ingredient as Sonar, so it will kill both Duckweed and Watermeal. Watermeal is a tougher weed to control, so it will require a higher dosage rate. You can still treat for the weed this year, but it may take 30–90 days to see full results. Early Spring is the best time for the treatment, usually about 2 weeks before you would normally see the weed develop. In either case, just be sure to use the liquid product as the granular does not release fast enough to be effective. When treating by pouring or spraying, you will want to make sure the product gets underneath the floating weed for best results. Duckweed and Watermeal can produce thick mats on the surface and the chemical will just dissolve in the sun before it penetrates the weed (if the chemical is just spraying over the surface of the water). Please let us know if you have any further questions.
We have an acre stocked pond that is poluted with watermeal. We bought Reward and tried to rig a garden hose to spray it, it did not work. How do most people spray this on their pond?
Malenda,
The sprayer we use to spray on any type of chemical is called our Airmax Pond Sprayer. You mix the product into the sprayer, build pressur by pumping the handle and then spraying by pulling the trigger. Just remember that Reward/RedWing is a short-term control of watermeal. If you are looking for season-long treatment of watermeal, I would suggest a href=”http://www.thepondguy.com/product/1585/212″>WhiteCap.
My husband’s family has about a 1 1/2 acre pond in SC. It is totally infested with duckweed. Some advice that they have heard is to get some grass carp the other advice it to get the chemical that will kill it this year. I am thinking that they need to do both, get the WhiteCap to kill it now and the grass carp for future maint, right? please advise.
Michelle,
Once duckweed begins to take over a pond, it doesn’t take long before it takes the whole thing over. Since the duckweed are prolific growers, you may find that the Grass Carp have a hard time keeping up with the growth. You may not see much of a decline once the duckweed gets a hold for the season.
Grass Carp do have some drawbacks. Some states, like us here in Michigan, restrict the use of Grass Carp for the sake of The Great Lakes. Grass Carp can really destroy a ecosystem over time.
I would highly recommend the WhiteCap. Its highly effective and simple to use.
My husband and I have a 1-acre pond that is currently covered with duckweed. This is the first time since we have lived there (9 years) that the duckweed has taken over so much. We also have some type of moss under the duckweed.
Have read your replies about WhiteCap. Is WhiteCap toxic in anyway to humans/birds/fish, etc.?
Is it too late to use it kill off the duckweed and get my beautiful pond back for this year? If we don’t get the duckweed under control, will it harm the fish we’ve stocked in the pond?
Finally, we used to have a pond that pumped water from the pond and sprayed it back onto the surface.
We thought this would be beneficial for the pond and helped add oxygen. Wondering your thoughts
on whether this is a good thing for a pond?
Laurie,
The only water use restriction on WhiteCap is a 30 day irrigation. When it comes to swimming, any wildlife or fish, you will be fine.
Duckweed is still in the growing season. The best time to treat duckweed is when it is still growing because it will take in the aquatic herbicide much more aggressively.
What can happen with duckweed over time is that it can cover your entire pond like a mat. If this is left like this it can cause a summer fish kill by limiting photosynthesis to the submerged plants below. This will deprive the overall pond of oxygen. If this level gets low enough, it will be lethal to fish.
From what you describe with the water spraying into the air sounds like you have a fountain. Fountains work great in ponds that are 6′ or less. A bottom bubbler diffuser such as an Airmax Aeration System works great when the water is 6′ or deeper.
Here is one of my blog post on aeration. Hopefully it sheds some light for you.
Thanks for the question. Take Care!
the the first time in 10 years my pond has watermeal growing in it. We have treated it with AquaShade but it only worked for a couple of days. We have had a maaive fish die off also since whe watermeal appeared. I
sorry sent message & was not through! I have horses that i removed from the pond when it started scumming over but would like to move them back to that pasture- have you ever heard of watermeal hurting horses if they drink it and also if we treat the pond with WhiteCap would it be safe for the horses as well? Thanks
I haven’t heard of watermeal hurting the horses so I think your okay there, but I have heard of watermeal causing a fish die off. Similar to what I mentioned about duckweed above. What can happen over time is that watermeal can cover your entire pond like a mat. If this is left like this it can cause a summer fish kill by limiting photosynthesis to the submerged plants below. This will deprive the overall pond of oxygen. If this level gets low enough, it will be lethal to fish.
As for WhiteCap, there are no water use restrictions except for a 30 day irrigation. So for animal drinking/swimming you are good to go.