Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Watermeal & Duckweed Treatment Diuron, Diquat,etc.

We have a 1.2 surface acre pond with a max depth of 9'-10'. We bought the property about 2 years ago, it was very neglected, overgrowth of trees etc. and same with the pond, by August it will be 100% covered with watermeal and some duckweed. We are located in Kansas. PH is neutral at around 7.0 when I last checked it. I did buy 7 grass carp to help with the natural approach as well as took out several trees blocking the wind from keeping the water agitated. We have done two treatments with Tsunami DQ and the recommended surfactant as the container suggested at the heaviest coverage rate. I applied at the first sight of watermeal and duckweed and when the water temp was getting warm. I mixed in a 40 gallon sprayer loaded it up in the boat and treated all edges where the watermeal and duckweed collected so far. I treated again in 4 weeks. This barely put a dent in the growth of the watermeal or duckweed. Some areas were killed by it but most were not, only discolored to a light green or in some cases yellow. The dead areas turned brown. After contacting Sanco Ind. (who has awesome service and cant say enough good about them) I was instructed to apply at much heavier ratios than what you would deduce from the label. That being said I was not going to spend the $120 and up per gallon to treat at the rates I was referenced. After the second treatment 3 weeks later the watermeal and duckweed was in full force. Another month it was taken over again. At which point is too late for herbicide treatments due to cost and potential impact to environment fish etc.

So now to my questions:
I do not intend to use Tsunami DQ based on my past experience and level of overtake that watermeal and duckweed has on our pond. I am considering Clipper or Diuron. I had purchased some Clipper last year after the second treatment but did not use due to not knowing if it could be used in combination with the Diquat based Tsunami DQ and due to the fact that by the time I got the Clipper the duckweed and watermeal were establish too well. Can anyone weigh in on this?

Additionally, Diuron is used by some local folks. What are the rates that someone could recommend and can it be used in combination with Clipper? Based on my reading of Diuron 80DF's information 2 PPM is the max application which is 25 kg per Hectare-Metre. If I assume that our pond has an average depth of 3 ft (~1 m) then we would have .5 hectare-meters. This would put us at ~12g can anyone confirm this? I would prefer to start at the conservative side so would rather consider doing around 6 kg or less. Anyone guidance would be appreciated.

Thank you in advance.

Once our water temps hit 50-55 I am planning on treating our pond. So please let me know what your best experience has been to knock out and infested pond early prior to the duckweed and watermeal taking over by late spring or early summer. Also if you have had experience with Clipper or Diuron please advise.

For the long term plan on draining and rebuilding this pond. Duckweed and water meal are plant indicators of a very old aged pond with hyper eutrophication and over enrichment of the basin. If you use the chemical method of control,,, plan you will have to do it every year due to the very fertile conditions entrapped in the pond. After many years you will turn the pond into a chemical depository with highly contaminated sediments. Chemical accumulations could easily make fish unfit to eat.

Diuron is moderately toxic to fish and highly toxic to aquatic invertebrates. In rats Moderate doses of 250 mg/kg caused wavy ribs, extra ribs and delayed bone formation. There were also weight decreases in offspring at 500 mg/kg. In pregnant mice given very high doses of diuron (nearly 2,000 mg/kg) exhibited reproductive and embryotoxic effects. Developmental effects were found in their offspring. Cattle fed small amounts accumulated low levels of diuron in fat and muscle, liver, kidney.

Here are the images from last year.

The trees along the dam (right side of photo 4-19-16(2) are now all removed. Is it worth of trying manual removal of as much vegetation and unwanted plant material as possible plus a treatment before doing something as expensive and destructive as rebuild? If so what would the recommended dosage be to do such? and of what?

Also this pond was built in mid 1970s per the original owners of the property. They kept it cleaned up and fed fish etc, until the late 1990s.

Talk to others here on the forum that have rebuilt their pond. Ask if it was a mistake.
Your pond is doing what ponds do - AGE and often that aging, as in life, is usually not graceful.
Dobsonfly asks: "Is it worth of trying manual removal of as much vegetation and unwanted plant material as possible plus a treatment before doing something as expensive and destructive as rebuild?"

It depends on how long you want to delay the inevitable, unless the goal is more of a wetland swamp than recreational pond. Natural processes are annually 'pushing' the pond toward a swamp. As the nutrients and bottom muck accumulate & increase more each year,,, the 'push' toward swamp condition becomes greater each year due to more of the driving forces.

The worth is dependent on how much time, money, and frustration you have to expend on delaying a clean out. Do your manual delay procedures until you tire of the annual frustration, expense and chemical accumulations. Don't think of it as a destructive process when in reality it is a rebirth and renewal for the pond. Knowing what you know now, if you could return to your years as a younger person would you do it?

When a rebuild is done properly the end result is - the amount of effort, time spent managing, overall effort and frustration are less, while the enjoyment of a new pond is almost always deemed as well worth the expense. Plus it adds value to the property. Been there done it.

In a pond rebuild, the pond can be down sized to be more manageable, yet still very enjoyable. Pond rebuilds can be designed so as to not incorporate some of the original features that contributed to the early aging and demise of the original pond.