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How do I know which chemicals will treat my weeds? | Ponds & Lakes Q&A

Q: How do I know which chemicals will treat my weeds?

Q: How do I know which chemicals will treat my weeds?

Henry – Markesan, WI

A: Weeds. Whether they’re algae or submerged, floating or shoreline plants, they’re a nuisance—not to mention a potential hazard to your game fish and pond or lake health. In order to manage these green invaders, you should get to know them a little better. Don’t worry: you don’t need to be a Master Gardener to identify and treat them. Here’s all you need to know:

1. Know the Weeds

Before you start dumping chemicals on the weeds in your pond, you’ll first need to understand the different types of aquatic weeds that pop up in lakes or ponds. There are four basic categories:

  • Algae. Algae comes in three basic types: Planktonic, which causes the pea soup look in your water; filamentous, which creates blankets of stringy stuff or pond scum; and chara or muskgrass, which smells like musky garlic. When you take a closer look, these weeds have no defined root systems, unlike their other weed cousins.
  • Submerged. Submerged weeds live underwater. This group of troublemakers includes bladderwort, several types of pondweed, watermilfoil, parrot feather and hydrilla. They look like a typical plant, with leaves, stems and root systems.
  • Floating. Floating weeds generally reside in shallow water and have root systems that reach into the water or down into the soil, allowing their leaves and flowers to rise to the surface. They include watermeal, duckweed, azolla and even water lilies. When not kept in check, these floaters can take over a pond in no time.
  • Emergent. Emergent weeds live along your lake’s shoreline. These plants like to keep their feet wet; their foliage, leaves and flowers live out of water, but their root systems prefer wet, almost completely saturated soil. Emergent weeds include cattails, phragmites, purple loosestrife and bulrush.

2. ID the Weed

Once you identify the category of weed you’re dealing with, head over to our Weed Control Guide and try to match weed with the picture. For example, is it a floating plant with a root system? Then you’re dealing with a type of floating weed. Is it completely submerged? Then you’re dealing with a type of submerged weed.

Each weed included in our Weed Control Guide will describe the best treatment options to manage it. Not sure of the weed? Snap a close-up photo and e-mail it to us at weedid@thepondguy.com. Of course, you can always call us toll-free for advice, too, at 866-POND-HELP (766-3435)!

3. Treat the Weed

Once you’ve ID’d the weed, treat it with its appropriate herbicide, remembering to always follow label instructions when applying it to your pond or lake. If you have fish in your pond, we suggest treating in sections as sudden changes in water conditions can affect aquatic species. Treat 1/4 – 1/2 of pond at a time, while waiting 10-14 days between treatments.

4. Remove the Remains

Once the chemicals start working to kill the weeds, make sure you remove the decomposing foliage with a weed rake, like the Jenlis Weed Razer™ Aquatic Weed Cutter. Why? Because anything dead will turn into muck and start the weed/algae cycle again—which is not something you want to happen, right?

Pond Talk: What tips do you have for managing aquatic weeds?

Broad Spectrum Pondweed Control - Pond Logic® Ultra PondWeed Defense®

Aquatic Weed ID: Chara Versus Pondweeds – Pond & Lake Q & A

Picture of Chara, a Form of Algae.

Pond & Lake Q & A

Q: I have mats of pondweeds in the bottom of my pond. I used Pondweed Defense to treat it, but it seems to be unharmed by it? What am I doing wrong? If there another herbicide I am supposed to use? – Ted of Michigan

A: I remember when I first began treating ponds the importance of being able to identify what I was treating was vital. For example, after talking with Ted we discovered that what he had in his pond wasn’t a pondweed at all , it was actually a form of algae called chara. Chara, (refer to picture on the left), mimics true plants with its shape and form. At times, its hard to tell the difference between chara and pondweeds by just their physical appearances.

Aquatic Weed Identification: Chara Vs. Pondweeds
Even though there are times when it may be difficult to tell the difference between chara and pondweeds there are a few distinct qualities that chara has that will help you set them apart from pondweeds.

  1. Skunky Smell: Chara has an awful musky smell. Simply walking close to or around your pond will tell you right away if you have a chara problem or not.
  2. Easy to Remove: Chara is not as rooted into the pond as pondweeds are and is extremely easy to pull out from the water.
  3. Gritty Texture: Diagnose chara by pulling some out and rubbing it in between your fingers. Chara has a gritty feel to the touch.

Treating for Chara: When treating for chara, since it is a form of algae, you need to use an algaecide. We prefer to use Algae Defense® , but you can also use Cutrine®-Plus Granular as well. Approximately two weeks after treating the chara we sugget to use a Pond & Beach Rake to rake out as much as you can (Note: DO NOT rake out chara before treating it, it will spread). Doing this will help you gain control relatively quickly.

WE CAN INDENTIFY WEEDS/ALGAE FOR YOU!: If you are ever unsure of what you have, just go ahead and send us a sample and we can diagnose it for you. Its FREE. You can either e-mail us a picture of mail the sample to us. See below for instructions.

E-mail: E-mail us pictures at weedid@thepondguy.com

Or

Mail: Mail weed samples to: The Pond Guy, ATTN: Weed Sample, 15426 Chets Way, Armada, MI 48039. When mailing just be sure to ship priority or exprss shipping to ensure the sample arrives quickly and fresh. Also, please wrap samples with a DRY paper towel and place in a plastic bag.

POND TALK: Have any of you had trouble identifying pondweeds or algae? Please comment and let us know how we can help.

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.

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