Please visit our Sponsors

FAQs on Pond Vascular Weed Control

Related Articles: Pond Vascular Weed Control, Pond Algae Control, Pond Algae Control with Copper

Related FAQs: Pond Algae, Control, Copper UseHornwort

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner

pond weeds   7/4.5/11
We have a lot of weeds in our pond and have tried several things to get rid of it, it is creek fed.
<Creates some issues re what might flow downstream... NOT biocides, herbicides>
I have heard if we get rid of the muddy bottom, it would help.
<Mmm, not necessarily. Depends on what the "mud" is made of, what other technologies you have, want to pay for>
It just looks so bad, we can't use it to swim or fish.
<... perhaps time to have "help" come out, take a look/see...
College/university, extension service, private consultancies... Bob Fenner>
Thank you

watercress overload in my pond   5/4/10
Hi Members of the Crew!
I have searched through the history and not found anything similar to my problem.
I have a large spring-fed pond on my property. I would guestimate the size at 12-15' x 35-40' varying from 6" to 3-1/2" deep. This pond is fed from at least three underground springs. The previous owners made a dam to form the pond and the overflow runs off into the woods and meets up with a creek.
I absolutely LOVE the pond. It is one of the reasons that I wanted this house so badly. There really is no way to control water quality since it is a free-flow situation where the water is in and out all day. I just do my best to keep the dead leaves from building up and keep the weeds from being horrible around the banks.
<You may want to look into "shooting" a "concrete berm" around the edge... will help maintenance tremendously>
There are lots of large rocks that edge the pond too but over the years they have gotten into the water.
<Ah yes>
I worked last year and redid about 1/3 of the banks and hope to finish the rest this summer.
I removed all the overgrowth from the rocks and rearranged them so it looks a lot better.
On to the problem...(you knew there had to be one right?) There is watercress in the system. It grows in the creeks and streams here and somehow it got into our main spring feed. It overgrows my whole pond if I let it and the only way I found to rid it is to remove it by hand. I took out five lawn wagons yesterday. (Whew!)
I have to next clear out the main
spring feed to diminish how much gets down into our pond. The spring feed is about 50' from the start of our pond. Then the overflow from the pond is completely covered in green. You can't even really see the water is there it is so heavy.
Do you have any ideas on how to prevent it from growing so freely? I do have some other pond plants that were already in there that I leave in place when I remove the watercress. And I am adding some donated pond lilies too.
Next pond project is to get a section of pond liner and remove the dam rocks
and lay on the liner and replace the rocks so that the water doesn't leave the pond so easily and will be about 8-12" deeper. We put in about $60 worth of 2-3" goldfish about a month ago and haven't seen one since that day.
Also about 50 feeders went in late last summer. Not seen them either. I thought they may have been in the watercress hiding but alas I pulled it all and didn't see one fish :(. So I assume that the fish must have gone out through the cracks in the dam as the water does now.
My only other thought is that since the water is spring water and is so very cold...could they still be hibernating in the mud? The water is probably about 50* at best. But it never freezes all winter. It stays completely open and the local ducks just love it!
Thank you for any thoughts & ideas as I am sure you will have some.
Thank you!
<Mmm, I do... but you'll need to check re the legality in your area... I'd look into Grass Carp... certified triploid... Ctenopharyngodon idella...
And make sure they can't get out, cause trouble if/when "washed over" your dam, going "downstream during flooding. As you state, there are no practical other means of control here w/ such new water influx. Bob Fenner>
This picture is of the inlet spring before I pulled the watercress last summer.
This picture is of the inlet spring after I pulled the watercress last summer.

Lilly Islands, pond maint. I am not trying to sell anything or have a service for hire this info is only to help anyone with the problem of floating lily pad islands of mud in a pond. After chemically treating the Lilly Pads, the large floating islands come up from the bottom they are unsightly, smell and cause swimming, fishing and navigational problems. Quick History The pond that I was working on is 10 Acers in size. The outfall structure was damaged in 1999 from hurricane Floyd here in South Carolina. Water was lowered approximately 3 feet allowing lily's to grow wild and hearty, this made the pond un useable. I fixed the structure for the residents in 2008 and used Navigate to kill the lily's at 150 lb per acre in a 1 acre area. <Mmmm> The Lilly's died the roots <Rhizomes...> then started to rise with mud islands incorporated. Goggle search only told me about many more of these instances but not the remedy. At this point we had the entire area filled with mud islands they were growing grass. <What a mess!> Solution: These islands are mostly connected to each other some are not. I positioned a Excavator in a good area for a storage pile for drying then removal. pulled in what I could from the area that the machine was parked. Then we attached a flat metal screen to the front of a small 12 foot aluminum boat. Similar to a wooden pallet as a push boat. this screen extended about 2 feet or slightly more into the water. I used a boat push pole to start moving the pads and a small electric outboard to also help. Then simply moved these large floating islands to excavator for removal. This process was hindered by the trees growing in the pond so it took 3 days to complete the 1 acre pond. <A huge effort I imagine> Email me if you would like a picture of the boat we used. I hope this helps as we tried several other methods and this one was far superior to all the rest. It actually was very fast once we were set up. The plant decaying chased out the fish from the area as the oxygen was absorbed, they are quickly returning with the aid of feeding. This pond went from a smelly eyesore to a beautiful pond in one week. I would recommend only treating approximately one fifth of a pond at a time so you fish are not harmed. Jimmy email me at _PROSANDBAGGER@AOL.COM_ (mailto:PROSANDBAGGER@AOL.COM) <Thank you for sharing, relating your experience Jimmy. I would have just raised the water level, allowed the lilies to die back in time, rather than using an herbicide in the first place. Bob Fenner>
Re: Lilly Islands 9/14/08
Bob , We asked Clemson that question before using the Navigate. They said it could be 30 years before the pads were gone although they would thin through the years. They did also send us a web site for a tool to cut the pads at the bottom but said this root problem may still arise. Using the Navigate was the decision that was made by the homeowner for immediately cleaning the pond. Jimmy <Mmm, we used our service account sites like this to make money... selling the rhizomes to/through aquatic garden centers of size... partly how I retired in 94. BobF>

Hornwort Q from SA, pondweed control  -- 06/28/07 Hi there <And to you> We live in Port Elizabeth, South Africa on a smallholding with a 2 hectare dam which is five metres deep. Our problem is that the dam is 60% covered by hornwort. <Ceratophyllum demersum, Coontail otherwise known as in the West> The dam is home to a large population of large-mouth bass, crabs, terrapins and many species of water fowl and other birds. <Neat!> Our neighbour who farms beef cattle uses the dam for his cattle and Lucerne. Could you give us any practical solution to bringing this problem weed under control? - Bearing in mind the creatures that the dam sustains. Regards Ken <Mmm, there are two possible avenues to pursue here... One biological (predation), the other chemical control... I am unfamiliar with your laws, and availability of predaceous (fishes likely)... but would ask that you inquire of your "fish and game" re the use of various "carps" (Big Headed, Silver, White/Amur)... and also the use of economic poisons here (there are efficacious ones to be used on such weeds...)... Keeping in mind what might become of the treated water after it leaves your property... making sure to test treat the water if going the chemical route... applying in "waves" to prevent death from oxygen depletion, other decomposition effects. Please do read here as well: http://www.wetwebmedia.com/PondSubWebIndex/vascwdcontfaqs.htm Bob Fenner>

Lilies d'Amour or lilies no more?  9/27/05 We have frontage on a fresh water lake. The lily pads have overtaken the water. We can't swim, boat etc. We've tried pulling them out by hand and with implements but it is evident we are losing the battle. Any ideas? <Mmm, a few... there are chemical herbicides that one can utilize... but these are pretty non-specific... and I don't know what your neighbors might think if you killed their lilies... And there's the issue of legality... where the water might go... irrigation, watering of livestock... There are biological controls, but these might posit the same issues... and then there is/are the manual side... it may come as a "happy surprise" to you to find that there are companies willing to buy your lilies... I would check your phone directories for pond service companies in the region re... and in turn, cast your net further, contact the national pond livestock suppliers (these are listed on WWM)... the cooler weather is upon us... so the lilies will die back... next year? Perhaps a combination scuba training/weed removal classroom....? Bob Fenner>

Controlling pond weeds 7/9/05 We have the weed Najas, in our 10 acre pond. What kind of herbicide would   kill this. It has taken over, we cannot fish or swim, or use our  paddleboat. <Mmm, at this point, either Aquathol or Reward... Please see here: http://www.aquacenterinc.com/chemicals/chemicals_3.asp Going forward, if your State allows, I'd look into biological control/s here... Grass Carp, perhaps another (triploid or no) carp species. Bob Fenner. Najas: http://plants.usda.gov/classification/output_report.cgi?3%7CS%7CNAJAS%7Cu%7C140%7C+63>

Water Lily Control Question We have a pond proximately 55 feet by 75 feet, with a depth of approximately one foot around the edges to approximately 7 to 8 feet at the center (it is shaped like a bowl). <How nice!>   We landscaped it with some cat tail on two sides, as well as other pond flowers, and we put a fountain in the center that works from early spring until late fall.   <Okay> Three to four years ago we made a big mistake in planting water lilies on the back/far side of the pond, directly in the ground in the water.  During the first two years the pond looked beautiful with the lilies blooming all summer long in small yellow flowers.  However, last year the water lilies somehow multiplied (perhaps the fountain pump in the center sucked in the seeds and sprayed them out all over) but the lilies spread and covered al of the pond surface area with thick pads of leaves during the summer.  Although this is good for the fish we have in the pond, it gives them shade and food, the pond does not look like what we want it to look like.  You hardly see any water anymore, just the lily pads and leaves. <I see> We try to clean the pond three times during the summer but it I very difficult to do because the water is very deep in the center, it comes above your head, and the only way to clean the pond is to float on a raft and pull out the lilies by hand, which takes a long time and is very hard to do on a hot sunny day. <Have spent MANY hours doing this myself> Do you have any advice for us as to how to put this lily problem under control, perhaps trim or prune them or even destroy them?  Can we use any tools you can think of to cut them 5 to 10 inches under water easily because they come back within a few days and the stem is 6 to 7 feet long under water from the bottom.  Do you know of any company that produces any tools (like weed eaters or grass cutters) that can work under water?  Also, do you know if we don't let them grow above the water and reproduce seeds, would it be possible to prevent them from growing the next season?  Or is there anything you know of (or can direct us to someone who may know) that we can do to put them under control without destroying the life and the fish that are in the pond? <There are gardening hand tools like "Hula Hoes" that can be adapted (longer handles) to cut the lily pad and flower stems near the bottom... and a possibility of diving to hand-remove the tubers... and chemical means (a bit dangerous to all livestock if too much is killed off all at once)... that can be broadcast via sprayer or pellets... even biological control means in some places (triploid carps of a few species)... nothing to just slow down for a season> I would greatly appreciate any assistance you could provide.   Thank you in advance, Blagoj Panovski <Having worked in water feature design, construction, maintenance for several years... I am given to suggest, if the problem is "that bad" that you drain the basin, let dry, and use a power tool (back hoe, skip loader...) to scrape the area clean, start again, with either blind potting the lilies or building berms... likely wire and re-bar, with some concrete/shotcrete... possibly a liner... to control their further expansion. Bob Fenner>

Vascular lake weed or algae... control Hi, We have a problem with an area right by our dock in a lake.  There is very tall grass, not sure if it is seaweed or just tall grass growing in the water however it is playing havoc with the propeller on our boat and it is hard to get in and out of the space without tangling the motor.  We have had to use an oar to get close to the dock on some occasions when the water is low.   Any ideas on what we can put in the water to kill the grass??? THANKS PAT DEPRE <First off, you need a real identification... could be what you are describing is actually not a true plant, but an algae... much more easily controlled in general (blue stone, aka copper sulfate, maybe with about 10 percent citric acid... broadcast in the shallows mid-day about and on this material)... if it's a embryophyte/plant there are chemical means of treatment, mechanical (like pulling it out, draining the basin and using power tools...) or biological approaches. But you must know what you're actually dealing with. Take a look on the Net using terms like "your geographical region, maybe the state", lake, weeds, control, identification... and see what you get, OR call other folks in the area who also have bodies of water, and ask for their assistance, OR the local authorities (fish and game and such) re... OR landscape supply companies and ask who does "lake management" in your area and have them out. Bob Fenner>

Elodea/Anacharis (eradication) Bob: <Bob>   My name is Bob Lombard  and I'm on a Commission for the Town of Stratford Ct. Our problem is we have a pond, 7 acres large, about 400' by 900' and a average depth of 4' and it is Loaded with Elodea/Anacharis. We use the pond for sailing model boats and we are trying to get rid of this weed.   Do you have any methods of how we can get rid of these weeds? <Mmm, I do (or should state I did... have been out of the pond weed biz for a couple decades now... likely technology has improved). A bunch to ask... about what other life is in the system you might want to keep... the disposition of water that leaves the pond (where does it go, what might it ill-effect?). And my one, good piece of "advice" (i.e. what I would do here) to contact the "Fish and Game" at the State level, ask in turn for "Pest Management" folks, agencies in CT and get their input. This may be a more/less simple job of employing a commercial poison (herbicide) at the local level... but might also be more involved... perhaps you folks could introduce some predators, competitors and effect a seasonal improvement... this would be my approach/strategy. Bob Fenner> Bob Lombard Stratford Ct. 06614

Hornwort and salt Hi from New Zealand <Hello from sunny Southern California> We (the Department of Conservation) are contemplating using salt to eliminate Ceratophyllum demersum (hornwort). <Mmm, this is Bob (Robert) Fenner... a long time pest control applicator and advisor licensee... someone had to qualify for our company's service division... and past member of Aquatic Plant Management Society, et al. organizations... involved in Hydrilla eradication programs here... and an all-round pet-fish sort of guy... who has cultured, sold large amounts of this plant (aka Coontail to folks here in the States). Not easily controlled with salt... we can/should talk over other control mechanisms... including commercial herbicides.> Hornwort is presently New Zealand's most invasive exotic macrophyte. Although hornwort has been present in the North Island since the 1960s, it has only recently made it to the South Island. <This stuff "really gets around"... like many other pest macrophytes via fishing gear, waterfowl... even ornamental aquatics mis-use (release to the wild)> Hornwort is a multi-million dollar pest for North Island hydro-electric power generators, principally because it causes blockages in dam turbines (the scope for disruptions to South Island HEP schemes is potentially even greater).  Hornwort is also capable of displacing the majority of our native macrophyte species and even some of our most invasive introduced macrophytes including Egeria, Elodea, Lagarosiphon.   <Does so in the U.S. as well> Fortunately eradication a still a realistic option (in the South Island) because of the limited extent of the present infestation.  A number of control options are being evaluated, the most promising of which is soil sterilization using salt (i.e. sterilizing the streambed substrate).  We have been able to desiccate the majority of the plant the floating-above ground component) using the contact herbicide Reglone (a form of Diquat). <Really... this is the product category (teratogens) I was going to describe... can you related the treatment protocol? Are you using a spreader-sticker? Need to know water temperatures, if you're spraying emergent material...> However, there is still the possibility of buried propagules withstanding a herbicide treatment hence, we need a soil sterilent that is inert (when in contact with organic matter) and which has a residual action such that it would saturate the streambed and eliminate any remaining viable buried fragments. <Mmm, yes... but a systemic might likely prove more effective...> Salt appears ideal in this respect particularly as trials have shown free-floating hornwort will perish if immersed in water of sufficiently high salinities. <Yes... but for how long, how high a standing salinity... what about the residual salt?> I was alarmed to learn that hornwort is included amongst a list of macrophytes that are suitable for brackish aquaria. <Yes, exactly... it is> Do you consider that it is realistic to expect that, if applied at sufficiently high salinities, salt will also successfully eliminate buried propagules (given hornwort's tolerance of brackish water)? If so at what concentrations (parts per thousand) should salt be applied? <Obviously, the only treatment regime I would trust is one that was tested out by assay... I would do a few experiments here... Unfortunately I know Ceratophyllum can be almost instantly placed from fresh to water of a spg. of 1.005... likely higher salt concentrations, w/o suffering apparently.> I really appreciate your help. Kind regards Matt Bloxham Biosecurity Contractor Department of Conservation Motueka Area Office New Zealand 00 64 3 528 1810 <Do try a few test plots... Again, I would utilize the Diquat (but can suggest other products...) with an oil... on emersed portions at standard dosage... during mid-day to afternoons, at temperatures of 55 F. or higher... Much to discuss re the allowance of other economic poisons in NZ, and concerns re run-off, toxicity issues... Am interested (parenthetically) if you've considered triploid carp species as bio-controls? Bob Fenner>

Hornwort eradication options Hi Bob, Thanks for such a prompt reply, couldn't believe it when I got back from lunch to find your message. <We aim to please... and must need reply ASAP or get hopelessly buried> We used a spray contractor to apply the Reglone.  He used an Aquagel formulation which was administered in 600mm wide strips (with 1m spacings) across the stream. <At about 1 gallon per...? Surface area.> At the time hornwort was at maximum biomass. Smaller infestations amongst willows were spot sprayed. Temperatures were in excess of 15 degrees Celsius (i.e. above the recommended minimum operating temp Forreglone) and spraying commenced in the morning to avoid problems with thermoclines. <Mmm, I am not so much inclined to be influenced by the last... more important that the weed be active metabolically... late morning to mid afternoon on sunny days> The worst affected stream section has significantly reduced flow with large areas of standing water (i.e. plenty of herbicide contact time) and was not at all turbid. It has been nine months since the Aquagel was administered and there is still no sign of hornwort regrowth. <Good> We are just coming into summer and in New Zealand, hornwort typically reaches maximum biomass in Autumn. <Yes, same here... late summer into mid-autumn> The contractor believes that the Reglone will eliminate the hornwort completely but we have reservations because of the issue of buried fragments which the Reglone is unlikely to touch.  Unfortunately there are no systemic aquatic herbicides presently registered for use in New Zealand. <Ahhh... a shame. Shortsighted... more pollution, trouble from their lack of availability, use.> We have certainly thought about using triploid grass carp, but decided against for the following reasons: This control option would involve significant habitat manipulation. For example, shallow areas of Moutere Stream would need to be deepened. <Really? Have seen the big three species used in very shallow waters... even have some footage of a Ctenopharyngodon "going terrestrial"! to get at shoreline growth.> If this control method were to prove unsuccessful, deepening stream sections may increase the suitability of these areas for further hornwort infestation (by slowing flow and increasing the rate of mud deposition). <Possibly> * Use of grass carp would rule out the option of simultaneously treating Moutere Stream's hornwort and pest fish populations (using the same methods).  Grass carp could only be introduced into Moutere Stream after attempts to eradicate pest fish had been concluded.  Any pest fish eradication attempt would ideally involve significantly dropping the water level (in addition to applying a piscicide) which would benefit other hornwort eradication options but not the grass carp control option. * We understand that Grass carp are inefficient digesters of food; half of the weed eaten may pass through the gut undigested.  Hence, there are doubts over whether grass carp are able to digest/process hornwort sufficiently to neutralize any viable propagules. The widespread dissemination downstream of partially digested vegetative matter/propagules is undesirable in a running water system such as Moutere Stream. <Would only establish a predator-prey equilibrium/dynamic> * The introduction of yet another exotic fish species to this stream: runs counter to the Department's objective of minimizing impacts from introduced freshwater fish species in the Nelson region as the stream already contains a significant biomass of tench and Gambusia. We intended dewatering the affected stream section using a weir and pumping to land so that the salt could be applied directly to exposed streambed, as we figured this would help maintain salt in its most concentrated form. We will certainly look at testing the salt by assay. <Only way to assess practicality, effectiveness.> Meanwhile, if you can think of any other way of eliminating the hornwort outright (including the buried component), we would certainly love to hear back from you (it is unfortunate that systemic herbicides are not an option for us). <Well... is the area involved absolutely huge? Have you done any testing re how deep the propagules are/might be? Another possibility (has been used for Hydrilla verticillata infestations in areas in excess of 50 hectares...) is to de-water, Vapam with cover (optional), scrape and remove sediment... to waste, fill areas... even to the sea... Expensive, drastic... but another possibility. Bob Fenner> Thanks again for your help Bob. Kind regards, Matt Bloxham

Aquatic Pool Growth (Zanichellia palustris) Hi: I am a homeowner with an in ground swimming in phoenix Arizona with an apparent very unusual aquatic plant growth problem and very much need your help. <I've seen the pic... not that unusual... as in unfamiliar to me> Specifically, the growth is located inside a 3/8 diameter pvc pipe connecting a pool water leveler well to the swimming pool. The growth appears to be based several inches inside from the well side. The growth is very white, looking very much like bean sprouts or the white root system growing from a plant in a vase filled with water. At one point the growth clogged the pipe disabling the leveler from functioning. Several months ago I managed to remove a large mass using a long test tube brush and water pressure from a hose. Attached is a photo of that removed mass. <Neat, oh...> We have ruled out the invasion or a root system from an outside plant or tree breaking into the piping. Our theory is that an airborne seed or similar growth entered into the leveler, attached itself to the pipe threading an began growing. It may be Bermuda type grass, or fountain grass. Could it be a type of fungus? <Not likely... though w/o the supplied image I would have guessed any number of types of organisms... including freshwater sponge!> I continue to remove the growth and it continues to grow back. Do you have any idea how I can get rid of this? Some have suggested simply light depravation. Any advise or insight you might have would be greatly appreciate. <This is very likely an old nemesis of mine, the vascular/true plant Zanichellia palustris... of which I could write many stories... having spent so many thousand hours removing it physically, and similar sums of money using herbicides for its control in ornamental "lakes" in S. California... If the location is localized as you mention (there are a couple of life phases, water fowl may be eating the other... I would "poison it locally"... probably with simple household or swimming pool bleach (sodium hypochlorite)... this will kill the material about your water level device... and not cause much trouble in your main system once flushed out. The material was originally imported on a duck, boat gear... and this is an invasive, largely unwanted species... a phase coming to the surface, clogging other gear, being unsightly... I would get rid of the small amount you have now. Bob Fenner> Thank you!

Algicide for water hyacinth WWC, Looking for EPA approved algaecide to kill water hyacinth in a lake. Have heard of a product called rodeo. We need about a 55 gallon drum size. Would love any other recommendations on other product info or where to get it wholesale. <... much to say, discuss here... Eichornia crassipes... what State... Would get the input of a certified pest control licensee... Do you have your own spray rig? I would hire out the application if of any size (an acre or more) to a licensed applicator... Over spray with Rodeo, Round-up... teratogens... even with good spreader-stickers is a tricky business. Fifty five gallons?! This is a huge amount. Bob Fenner> Thanks, Rocky Hawkins

Pond? (vascular weed control) Zone 6, NJ I have a spring fed pond in my backyard, full of frogs, newts turtles etc. <Neat> Its about 25" x 15. 6 feet deep in the very center. Its about 7/8 over run by strands of long, rootless green growth. These strands flower with tiny green flowers on the surface. Its covering the entire pond except for the very center ( the deepest). I wonder if all this long grassy growth will choke the pond. Should I remove some or all of this growth from the pond? <Due to the flowering parts you can tell this is a true/vascular plant, not an algae... Nonetheless, do keep it in control by physically removing a good part of it on a regular basis (a rake with a line attached or an extension pole and other swimming pool gear will do here... Dragged the material out on the shore and let it dry for a bit (it's mostly water)... Periodic removal may save the day, should the plants overgrow, choke out other wildlife, or worse, bring about an oxygen collapse overnight. Please read over the pond maintenance section on our site: www.WetWebMedia.com for much more. Bob Fenner>

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner
Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: