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Weed Control in Private Lakes


Horton
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Looks like I am taking over the responsibility for weed control at my lake.

 

We use dye in the summer to keep the sunlight from reaching the bottom. Dye is sort of ugly but it is better than weeds.

 

In the winter we lower the water so we can spray pre-emergent where the water will be 24 inches or less deep.

 

Wondering what other private lake owners do for weed control. Given a choice I would use as little chem as possible.

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Agree on low use of chemicals. But, I have found diquat dibromide to be very effective.

Known as Reward by Syngenta. And, it is safe for fish. Generic brands will run about $200-250 for 2-1/2 gallons. And, that should treat a full ski lake.

I had a very serious problem. So, I used the Reward to kill the large, established growth. And, small grass carp for new growth. Problem solved.

You may not be able to buy diquat in CA. I saw a list of about 5 states that do not allow it to be sold there, including CA.

How deep is your lake at normal level?

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Diquat is a liquid. So, I poured it into a plastic tub of oil dry. After letting the oil dry absorb all the diquat for a couple days, I just idled all over the lake and broadcasted the oil dry from the swim platform with a Dixie cup. This gets the chemical close the the weeds. As it slowly releases from the oil dry, the weeds croak.
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@Zman do you know how diquat works on Phragmites (invasive cattail)? We have been in a battle to keep them off our shoreline. We don’t want to use Roundup like chemicals so have been using high strength 30% vinegar and salt along with cutting. Vinegar/salt/dawn soap mixture could be an option for lesser weeds that are on shorelines. Phragmites are taking over the Midwest and are really hardy though.
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@zman the oildry technique is genius, what is the name of some of the off brands that you have found for $200-$250.?

@A_B unfortunately the only thing I have found to work on the Phragmites is round up or similar, I make a trip around the lake on the quad every couple of weeks and catch them early so I don't have to use very much.

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@Horton - what kind of pre-emergent are you spraying? If it is a non-aquatic variety I wouldn't be surprised if the chemical is being diluted at the soil surface and leached out of the sub-soil when you re-fill the lake. Often the aquatic herbicides are a bit more expensive, but, they are formulated to work in water. Most non-aquatic herbicides break down or dilute with water to the point they are not effective. My organization sprays a lot of pre-emergent (roughly 15,000 acres worth a year), in dry areas we get about 3 years out of it, in our rainier areas, we are happy to see two years of effective weed control. The key to using less chemical is using the proper chemical in the proper location with the proper method (follow the label).

 

The UC system has a pretty good Ag Extension service, you might try reaching out to them for guidance. They are professional consultants that your tax dollars pay for. They may have a non-chemical solution. There are a lot of factors that go into choosing the right chemical and/or right formulation for a given species. As a research scientist who works with herbicide effectiveness (I stay on land for work) I can not stress enough the importance of a local, licensed, professional.

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We ski on a public lake that is a state park. After a very long battle with milfoil and objections from some lake front property owners there was finally approval to treat with Diquat after a lot of research on potential issues. There have been no negative impacts to the lake and the impact on the weeds was excellent.
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I'm simply a guy that has taken care of our 22 acre ski lake off and on over the last 20 years (not a professional). Obviously, you can avoid chemicals altogether, but the plan-of-attack is limited. That would largely entail dyes and sterile grass carp. The downside of dye is it is dilutive (in the event of heavy rains---flushing water out of the outlet). Grass carp take about 3 years before they reach their full consumptive potential. Their consumptive potential plateau for a couple years, and then decline. After year 7 or 8 they are simply 5 foot long monsters just swimming around with substantially reduced consumptive strength. Candidly, I like grass carp as a control method, but you will need to re-supply about 20% annually in order to keep the collective stock consuming in the optimal "plateau" range.

 

As to "chemicals", if you want "easy" look into Sonar or Tradewinds. Both are easy/quick to apply. Downside is that you may not be able to irrigate lawns from the lake for 90 days, and you'll need to be careful about other restrictions. Tradewinds is used by many to primarily control Duckweed, but I have found it effective (at times) with general evasive weed growth---except for large and small pondweed. A product by the name of Aquastrike may also be a good bet. As I understand it, Aquastrike is essentially a "cocktail" of Clipper and Diquat (i.e. my novice take). A key advantage over Sonar and Tradewinds is the fact that Aquastrike is a contact herbicide, with limited irrigation restriction. A disadvantage is that you have to dilute the product with a lot of water, which makes it much more time-consuming and equipment intensive to apply (with 3 or more applications needed during the skiing season). As to Aquastrike, if you can get it on without a heavy rain within a few days (i.e. flushing water out of your lake), it should do a good job. Sonar and Tradewinds, conversely, work over a period of weeks (not days) and quantities applied will dilute in the event of a "flushing" rain. All-in-all, I have found that chemical weed treatment is an "art", not a "science", and timing, weather conditions, chemistry, and follow-up are all very important. Also, the chemical that worked good last year, doesn't always work well the next year. Like BCM stated above, this is why many hire local, licensed professionals.

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@A_B I'm not sure how well diquat works on Phragmites. I see @Kurt commented his experience.

@kurt I got the oil dry technique from my supplier for the grass carp. It was very effective, easy, and not messy.

I don't recall the generic brand, there are lots of them. Just be sure it is 37.5% strength, then go with the cheapest you find with Google.

The figwort weed we had breaks loose, and still thrives while floating. Just for our initial treatment, we used a pump-up sprayer for the floating mass. Oil dry method for the immersed weeds to get good contact to the weed leafs.

When treating weeds with a herbicide, be sure to only do a section of the lake at a time. For a typical ski lake, maybe one-third of the lake at a time. If you do too much you will deplete too much oxygen in the water, which can result in fish kill. Not the chemical hurting the fish, but the temporary lack of oxygen.

Doing portions also reduces your risk for causing an algae bloom. You could also add a little Cutrine to help prevent algae.

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One other thing. We were in south Georgia, and got a lot of help from the local UGA ag extension. A professor came to our lake, ID'd the weed, then gave us a list of recommended herbicides. Very helpful, as noted by @BCM
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@BraceMaker "Anyone ever hit those 5 foot carp when skiing?"

 

I was boat judge for a jumper who had one jump in her lap during the turn! No injury but I gave her a reride. Not as bad as the geese at Bel Aqua...

 

I'm going to have to build a mechanical weed harvester. Just get your dye in early and keep it very blue.

 

Eric

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@fu_man ... depends on the type of weeds your working with. If its something that isn't extremely invasive, then the cutting and removing the weeds can be pretty effective with out a lot of maintenance. If it's something that tends to spread rather quickly then the weed cutting and removing it is a great head start when you add fish / chemicals / die to help with weed prevention. Makes it more manageable.

 

Take Lapoints lake in Orlando for example, terrible weed problem, we came in and removed the heavy stuff as deep as we could (4-5 ft below the surface) and Lapoint got enough fish in there to maintain the results. It is now one of the clearest / cleanest lakes I've worked on in Orlando. With out any issues from when we originally cut almost 2 years ago.

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@Z_Dub I've seen that done up here too - seems most lakes they let the spring weeds get to the point where it is hard to use the lake then they give it an early summer chop which seems to last them through the season. The guys in Wisconsin were making it into compost and selling the soil at a garden center. Kind of clever.
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@sgilbert is right when he says it more of an art then a science. What works for one lake and weed(s) may not work in another. We went the rought of chems to knockm back and carp to maintain. In general for anyone looking for help, you can get local agencies and perhaps a local university to do an overal plant assessment on your lake which gives you an idea of what types of plants you have and how much of each. They can then recommend, based on local controled successes, what to use on the invasive plants. We were very successful and have been for 20yrs now based on recommendations from those in the know locally.
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We can't get carp because the state says we are in a floodplain or there is a creak or some other clearly stupid bull shit.

 

In years past the lake owners here lowered the lake 2-3 feet and sprayed Duiron (Karmex) as a pre-emergent + RoundUp on the exposed shallows. Those chems sort of freak me out.

 Goode ★ KD Skis ★ MasterCraft ★ PerfSki ★ Radar ★ Reflex ★ S Lines ★ Stokes

Drop a dime in the can

 

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If the weeds are dry you can try the 30% garden vinegar mix. Probably lots of recipes online. Mixed with sea salt and dawn soap. I bought a 4 gallon backpack sprayer from Harbor Freight. It burns out whatever you hit with it. Phragmites have been thinned out bit not eradicated. Lesser weeds may get knocked out without the scary chemicals.
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I do agree that using non chemical means to control weeds and algae are the best courses of action. I can not help but bristle a bit when science does not support the claims made against chemicals. This is a quote from the reporting on the Monsanto case:

 

We are sympathetic to Mr. Johnson and his family," Partridge said. But he added that the court decision "does not change the fact that more than 800 scientific studies and reviews . . . support the fact that glyphosate does not cause cancer, and did not cause Mr Johnson's cancer."

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@Golfguy

 

You just quoted Monsanto V.P. Scott Partridge.

 

That is a lot like if an executive at Ford Motor Company told you the 1978 Pinto gas tank design was not faulty.

 

My wife is a scientist (agronomist and entomologist) for one of the nation's largest organic farming companies and she is uncomfortable with glyphosate. We use it sparingly and with caution around our property.

 Goode ★ KD Skis ★ MasterCraft ★ PerfSki ★ Radar ★ Reflex ★ S Lines ★ Stokes

Drop a dime in the can

 

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This lawsuit will be interesting, watching the source is very important. Articles in major journals can be flawed... but.

The national cancer institute published this article back in May; https://www.ncbi.nlm.nih.gov/pubmed/29136183 which is perhaps damning for the result of that lawsuit. Lawyers will be getting rich.

 

And that's an article specific to applicators who are applying hundreds of gallons of the stuff.

 

I'm opposed to the usage not due to direct impact on health but due to the rising tide of roundup resistant crop. Just like the antibiotic resistance of bacteria around us these weeds are getting resistant to the roundup.

 

Plotting any one thing to another though can be challenging, ven diagram of people using round up to people exposed to diesel fuel is just a circle.

 

And clearly round up causes celiac disease;

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And organic farming causes autism.

 

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@BraceMaker Thank you for the support. If there is any scientific documentation that Glyphosate has any health risks than let it be seen. Not a litigation aimed at deep pockets. I am sensitive to this issue, as I am also an agronomist.

 

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@Golfguy not a fan of the stuff either, I just think the evidence isnt there specifically to roundup/lymphoma.

 

I use it sparingly while wearing gloves to target poison ivy in areas I cant physically remove it. But should we spray between rows of genetically modified crops?

 

I do no-tillage gardening using cardboard to smother weeds, so make no mistake I wouldnt want to spray it in a lake and then swim around in it.

 

What annoys me is the deluge of the round up cancer click bait when a civil lawsuit judgement is the evidence for the article.

 

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I think we all are on the same page in this discussion. The most important factor in my opinion is to know your lake environment and identify your largest problem. We use pesticides as per the label instructions, and sparingly only when necessary to keep our lakes and landscape in acceptable condition for our selected purpose. There are many very good comments in this thread with excellent ideas. Controlling unwanted pests (weeds) in an aquatic environment where few can be tolerated is a complex task. Needing a broad reaching program. Many factors exist such as water chemistry, nutrient load in the water, level of tolerance to some or no weeds, geographic location of the lake and so on. My approach to our lakes (in the SW) is based on these factors. Summarized: We have an aquatic pest control consultant that tests the water chemistry and nutrient load yearly and we have established a data set. Weeds and algae will only thrive where the conditions allow, sun light and nutrients are required. Reducing both will help but is not all that is required. Grass carp, if allowed, work very well in controlling emerged weeds. Other fish such as Tilapia work well in controlling algae for us. If necessary, we use Chelated copper to control algae, such as Golden algae. This is not done unless the population of the target pest exceeds tolerable levels. Any aquatic herbicide is applied by a licensed aquatic pest control company. We have only had to use these services two times in the past 20 years. By monitoring and reacting appropriately to our condition, not hesitating to properly handle and apply algicides and herbicides, we have been successful in providing a great skiing environment. Geographic location of the lake will vary the necessary programs greatly. A lake in the south east is a very different animal that one in the Arizona desert.

 

Anyway, sorry for the long rant. Cheers and Happy New Year.

 

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Our lake is ultimately used on potato crops and we are therefore unable to use many of the usual weed controls - potatos are very unique crop. We have been using copper sulfate once or twice a summer. Am I to understand that this ia a bad idea?
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@jipster43 I think the risk of Copper Sulfate relates to killing off too much at once and the subsequent collapse of oxygen to support a healthy fish population. We used Cutrine for years on our algae until we started using blue dye and Sterile Amurs.

 

Europe has banned some of the glyophosates and GMO stuff, but not saying they are right. Look how messed up they are now on immigration.

 

I assume if it really was as bad as some say, the farming and lawn care industries would have been decimated by lack of workers by now.

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@jipster Depending on where your lake is located, and the alkalinity of the water, copper Sulfate may or may not be a good idea. If you have water that has a high calcium content, the sulfate bound copper will precipitate to the bottom of the lake and be less effective in controlling alga. ( think lake in the west alkali, in the east more acidic) Eventually sulfate will accumulate on the bottom of the lake and create a very bad environment for crustaceans. These are the critters that keep the bottom of the lake from being mucky. @A_B With any copper treatment it is important to be sensitive to the fish population and treat the lake proportionately dependent on the concentration of chemical used and the population of the weeds/algae.
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