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 Identifying Weeds in Ponds

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When you have a pond in your back yard, whether it’s a stormwater retention pond, or a decorative pond for your garden in your back yard, it may have an algae or pondweed problem. You need to be able to identify those weeds before you can treat the weeds to get rid of them.
The first thing you need to do when identifying a pond weed is to determine if it’s a floating pondweed, an emergent pondweed, or a submerged pondweed. If you have a floating pondweed, it’s pretty easy to determine if it’s duckweed or a filamentous algae. It will be something that floats on top of the water and moves back and forth with the wind. So, you’ll see it moving from one end of the pond to the other depending on the direction of the wind.
Submerged pondweeds can be either be rooted on the bottom, or they can just be under the water floating around. To determine what the weed is, you may need a rake to pull them in from under the water so that you can take a look to see what it is.
The emergent weeds are going to be along the edge of the pond. They’re the ones that stick up and have roots in the ground. They might be in the water, or up on the edge like these cattails. 
Once you have your weed, you can take it to your local extension office, and they can help you identify that weed. Seal it up well in a zip-lock bag, or in a jar. Make sure it’s well sealed, and take it in the day that you collect the plant. You don’t want to leave it sitting in the car for several days where it will get hot and start to decompose and smell bad. So, collect the sample and take it to the extension office in a timely manner, and they’ll help you find out what kind of weed your pond has.
Or, you can hop online. Go to the link provided on the Kansas Healthy Yards website, and follow it to a great website that can help you identify your pondweeds with pictures and descriptions about what your weed looks like. Then, you’ll be able to determine what kind of weeds you have in your pond.
This feature story prepared with Tonya Bronleewe, Kansas State University Research and Extension Agriculture and Natural Resources Agent, Sedgwick County. For more information, visit your local county extension office or visit our website at KansasGreenYards.org.