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What chemical should I use to treat water milfoil? | Ponds & Lakes Q&A

What chemical should I use to treat water milfoil?

Q: What chemical should I use to treat water milfoil?

Douglas – Goddard, KS

A: Before we dive into how to treat this aquatic invader, let’s get to know it a little better first.

Water milfoil, also known as Eurasian Water Milfoil (Myriophyllum spicatum), is a submersed aquatic plant that’s native to Europe, Asia and northern Africa. It has feather-like leaves that grow from white, red or brown stems, and some species produce four-petaled pink or reddish flowers that rise a few inches from the water’s surface.

Eurasian water milfoil thrives on fertile, fine-textured, inorganic sediments. An opportunistic species, the plant prefers water bodies that receive nitrogen and phosphorous-laden runoff, like a farm or agricultural pond. Growth explodes when water temperatures rise, which promote multiple periods of flowing and fragmentation (or when pieces of the plant grow roots and develop new plants).

If left unchecked, water milfoil can dominate a pond or lake in no time.

Controlling Growth

The good news is that you can find myriad products to manage this invasive species. The chemical you choose has to do with several factors.

Closed or open system? If your pond is mostly covered with water milfoil, does not have water flowing in and out, and is not used for irrigation, SePRO Sonar™ A.S. Aquatic Herbicide will be your best choice. The product uses the active ingredient fluridone, which effectively controls a wide range of floating, submerged and emergent aquatic vegetation including duckweed, hydrilla, bladderwort, naiad, elodea, water lily, coontail, pondweed and water milfoil – giving you more herbicide bang for your buck.

Small area or large? If you’re treating a smaller area of a pond or lake, Aquathol® Aquatic Herbicide works like a charm. It’s a rapid-acting contact herbicide that drops aquatic weeds below the water surface in four to seven days, though heavy growth may require a second application in 10 to 12 weeks.

Spray or granular? If you prefer granular herbicides to spray ones and have a smaller area to treat, choose Navigate. This granular herbicide is ideal for spot-treating weeds around docks, beach areas and shorelines, killing the roots of both submerged and floating plants, including water milfoil, coontail and water lilies. You’ll see it go to work within 10 days; you’ll see full effects in three to five weeks.

Plant, Human Considerations

When choosing a chemical herbicide, pay special attention to use restrictions. Some of these products have limitations for use in irrigation ponds, swimming holes and other situations until the chemical has adequately broken down in the water.

Also consider the other critters – plants, fish and animals – that live in your pond. Certain products can harm game fish, koi or goldfish, and can kill off prize water lilies and other welcome aquatic plants.

Pond Talk: How do you manage invasive plants in your pond or lake?

How Do I Treat Duckweed? | Ponds & Lakes Q&A

How Do I Treat Duckweed?

How Do I Treat Duckweed?

Tim – Rock Hall, MD

Duckweed is a very small floating plant about the size of a pencil eraser. It has shoe-sole shaped leaves with a small, hair-like root hanging below. Since duckweed floats on the surface of the pond, it is commonly mistaken for and treated as if it is algae. Unfortunately, algaecides have no effect on duckweed but there are a couple treatments you can do to keep the prolific duckweed at bay.

The Short-Term Solution
To treat duckweed as well as other aquatic weeds on a short-term basis, you can use Ultra PondWeed Defense® . This product is great for a one-time treatment or for spot treating. These are, however, only short-term solutions for duckweed. Due to their aggressive nature, duckweed can grow back in as little as 3 to 4 weeks. This is why we suggest a longer-term solution.

The Long-Term Solution
One of the only products on the market to provide long-term, season-long control of duckweed and other aquatic weeds is called Sonar™ A.S. Instead of having to spray the plant directly, Sonar™ A.S. is sprayed directly into the water. Sonar™ A.S. works by preventing photosynthesis in aquatic plants and by doing so causes them to slowly parish. Treating duckweed and other aquatic plants in this fashion allows for complete control of the entire water body for the season instead of just a few weeks.

I have a small floating weed in my pond. I think it is duckweed, how do I know and how do I treat it? | Pond & Lakes Q&A

I have a small floating weed in my pond. I think it is duckweed, how do I know and how do I treat it?

I have a small floating weed in my pond. I think it is duckweed, how do I know and how do I treat it?
Jason – Raleigh, NC

Duckweed can be a real nuisance if not identified and treated correctly. As it is a prolific grower it can quickly make your pond or lake look more like a golf course in a relatively short period of time. Duckweed is a small floating weed with a single root hair extending from the bottom of each individual leaf. Each green leaflet is about 1/8” of an inch in size and you should be able to fit about 5 to 10 on the tip of your finger. Duckweed can sometimes be confused with watermeal which is also a small green floating weed. Watermeal differs from duckweed in that it is much smaller and has a grainy or almost sandy feel to it if you hold it in your hands.

You can treat duckweed with two different methods. The first method is by spraying contact herbicide like Ultra PondWeed Defense® & Treatment Booster™ PLUS directly onto the floating masses with a pond sprayer. This method typically yields fast results but tends to be a quick fix that ends up resulting in new growth reforming over just a few weeks. If you need to whip your pond into shape for a planned day or two event, then spraying your pond with a contact herbicide may be an appropriate treatment for you.

For longer lasting control of duckweed you can treat the pond with Sonar™ A.S. aquatic herbicide. This product works by inhibiting the plants ability to produce carotene and as a result chlorophyll is degraded by the sunlight and the weed dies. There are however a few things you will need to check before adding it to your pond to ensure a successful treatment. Most importantly, Sonar™ A.S has a 30 day irrigation restriction meaning that if you water your plants or grass with your pond water you will not be able to do so for at least 30 days. Secondly, Sonar™ A.S needs to maintain a high concentration in the pond for up to 90 days. If your pond is prone to overflow or has an inlet/outlet chances are that the Sonar™ A.S will rinse out of your pond to quickly making the treatment less effective. A good way to visually check your water loss is to color the water body with pond dye. Dye will typically remain in your pond for 2-4 weeks in normal conditions. If your pond looses color sooner then it is a great indicator that too much water is exiting the pond. As Sonar™ A.S is degraded by sunlight it is important that you dye your pond while you are chemically treating the water body. When applying Sonar™ A.S use a pressurized tank sprayer and submerge the spray nozzle to apply the herbicide beneath the surface of the pond where it is safe from evaporation and sun exposure.

The best time to use Sonar™ A.S is early in the spring a couple of weeks before you normally see duckweed forming in your pond. This will give the herbicide a chance to establish itself in the pond and discourage plant growth before it gets out of control.

Pond Talk: Have you experienced Duckweed in your pond?

My pond is covered in duckweed. What can I do to treat this stuff? – Ponds & Lakes Q & A

Duckweed

Q. My pond is covered in duckweed. What can I do to treat this stuff? – Tony in Indiana

Friend or Fowl
A: For the lucky pond guys and gals out there who have never experienced duckweed in their pond, or those of you who think you may have it but are unsure; duckweed is a very small floating plant with kidney shaped leaves and a small hair-like root hanging below. It is approximately the size of a pencil eraser and is frequently misidentified as algae. It can cut off sunlight to submersed plants and cut off oxygen to fish and other wildlife. Duckweed is an extremely prolific grower and can quickly cover an entire pond making it frustrating to treat and maintain. More often than not, duckweed is introduced into your pond by hitching a ride on the feet of waterfowl.

Don’t Go Daffy Over Duckweed
There are two great options available to you in your fight against duckweed. Choosing the product that is right for you depends on the time frame you have to treat your pond. For fast acting, short term results, you can use a contact herbicide like Ultra PondWeed Defense® . Treatments with these types of herbicides work best on mature aquatic plants that are in a contained environment. Multiple treatments are typically required for effective short term control. It is important to remember that whenever you are treating large amounts of weed growth, only treat one third of the pond at a time and implement aeration whenever possible to ensure safe oxygen levels. When treating with Ultra PondWeed Defense®, we suggest that you use a tank sprayer to apply the herbicide directly onto the weeds. Ultra PondWeed Defense® has some water use restrictions, see label for details.

For long term treatment of duckweed, we suggest using Sonar™ A.S.. By adding Sonar™ A.S. to your pond in early Spring, you will inhibit the weed’s ability to produce carotene, a pigment that protects the plant’s chlorophyll. Without carotene, the sun quickly degrades the green chlorophyll and the weed dies. Sonar™ A.S. must stay in your pond for up to 90 days for maximum results, so if your pond has a constant overflow or you are experiencing heavy rains, you may need to include additional treatments. Sonar™ A.S. is degraded by sunlight, so when applying, make sure you spray the product directly into the water and not onto the plant foliage itself. Also, adding Nature’s Blue™ Pond Dye after treatment will help prevent sun degradation as well as track water dilution from heavy rains. Sonar™ A.S. has a 30 day irrigation restriction.

POND TALK: Have you ever experienced duckweed in your pond? What did you use to treat it?

Is there anything I should do for my pond/lake to prepare it for Spring? – Ponds & Lakes Q & A

Dyed Pond

Q: Is there anything I should do for my pond/lake to prepare it for Spring? – Dan in Illinois

Breaking the Ice on Your Spring Pond Projects
With the sun shining brighter than ever and the snow finally disappearing, most of us pond guys and gals are itching to throw on our waders and dive into our ponds — figuratively of course.

As the Saying Goes, “An Ounce of Prevention…”
Ok, so none of us really want to spend our spring and summer in waders pulling weeds and tending to unruly ponds. So what can you do to ensure your Winter/Spring transition is smooth and enjoyable? As the saying goes, “An ounce of prevention is worth a pound of cure.” This is especially true in the months to come. Following some easy procedures will keep those waders in your closest and a smile on your face.

Do Your Pre-Spring Cleaning
Walk around your pond and pick up any debris that has made its way into your yard and around your shoreline. If left to sit, this clutter will turn into a food source for algae in the spring. Cut back any weeds or unwanted vegetation growing around the pond while it is still dormant, keeping it from taking over your pond as the temperatures rise. Now is also a great time to inspect and clean your aeration system cabinet and, if the ice has already melted in your pond, the plates as well. This would be a good opportunity to move the plates back to the deeper areas of your pond for summer aeration, if you happened to move them to shallower areas during the winter.

Shaken, Not Stirred
With all of the dye, beneficial bacteria, and occasional algaecides we’ve added to our ponds over the seasons, you just may be qualified to tend a tiki bar at your pond. While your PondClear™ and EcoBoost™ get the back shelf for the winter season, you should be adding dye to your pond year-round as algae can still grow under a layer of ice in the colder months. If you have not been doing so, add your dye now to reduce the amount of sunlight available. Preventing algae growth now will keep you from fighting an algae bloom in the spring. Your PondClear™ and EcoBoost™ treatments should continue once the water temperature is above 50º F. For those of us who suffer from Duckweed, as spring approaches, you will want to have your Sonar™ A.S. on hand and ready to apply come mid-April so it has a chance to go to work and prevent weeds from growing throughout the season.

Take Inventory
Kris Kringle is not the only one checking his list twice over the winter. Pond guys and gals everywhere should be checking their remaining ClearPAC® and necessary weed control products and replenishing these items for the upcoming season. Inspect your tools and decoys to make sure they are in working condition. With everything in working order and ready to use, you are now ready for anything spring sends your way. All that’s left to do now is enjoy your pond!

POND TALK: How do you break the ice on your Spring pond projects? What do you have planned for your pond or water garden this season?

Controlling Pondweeds: Duckweed – Pond & Lake Q & A – Week Ending March 28th

Picture of Duckweed Floating in a Pond.

Pond & Lake Q & A

Q: Last year I had an uncontrollable case of duckweed in my pond. It covered my entire 1/2 acre pond! I’ve heard of your product called WhiteCap and wanted to use it this spring. I don’t see any signs of duckweed yet, but was wondering if it is too early to treat.
– Cameron of Michigan

A: Duckweed can take over a pond. This prolific grower can come from many sources although most commonly brought in on the feet of waterfowl such as ducks, geese or even herons. The small plant can stick to the feet or the feathers of such birds and be carried for miles. Duckweed can start out slow and in some cases take several seasons to become a problem, although I would recommend treating for it as early as possible.

There are a few options when treating duckweed. You can use a fast-acting aquatic herbicide such as Ultra PondWeed Defense® although this will only give you temporary relief and require multiple applications of spraying the duckweed directly. These are not usually suggested unless your treatment areas are not contained or you have heavy water turnover. When possible I always suggest Sonar™ A.S. since it is the least expensive method of treating an entire pond, is easy to apply and lasts an entire season.

We recommend to use 32 oz or 1 quart per surface acre (4-6′ deep) when treating for duckweed. This means Cameron’s 1/2 acre pond can be treated with just 16 oz of Sonar™ A.S.!

To answer the question above, treat with Sonar™ A.S. in the early spring before the duckweed even appears. This will allow you to get ahead of it before it reaches the surface. Although you don’t generally see it Duckweed is actually growing at the bottom of your pond long before you see it at the surface.

There are also other nice benefits to Sonar™ A.S. such as: It works very slowly so there is no chance of oxygen loss that could harm your fish or other aquatic life. Sonar™ A.S. is also very effective at controlling most other nuisance aquatic plants. So when your treat for your duckweed you will be controlling most other species as well.

Please Note: Sonar™ A.S. needs to stay in your pond for up to 90 days. It is not recommended to use it in ponds with a heavy overflow or when during times of heavy rain. If you are unsure of your pond’s turnover (or amount of water that is exchanged) use Nature’s Blue™ Pond Dye to shade the water column and track the time it takes for the color to disappear. You may also use Nature’s Blue™ Pond Dye during a Sonar™ A.S. treatment to track turnover and shade the pond from sunlight which can also reduce the life span of Sonar™ A.S.

Controlling Duckweed & Watermeal – Pond & Lake Q & A

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

Picture of DuckweedA: 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 is to use a product called Sonar™ A.S.. The best way to get rid of watermeal is to use a product called Clipper™. Sonar™ A.S. 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.

Both Sonar™ A.S. and Clipper™ 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.

Picture of WatermealFor more information on these herbicides and the aquatic weeds they will control, click here.

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