Algae & Plants on their Way - The Stewards of Water Blog

Algae & Plants on their Way

     With warm weather on its way (or already here in some parts of the country), the growth of nuisance algae and aquatic plants is right around the corner. With that in mind, Stewards of Water will be sharing archived content (updated and expanded), featuring videos, in-depth articles, and advice from the SePRO Stewards, covering the types of nuisance algae and plants you are most likely to encounter this season. 

     First up is this small plant, often confused for algae.

Duckweed (Lemna minor)






Duckweed has shoe-sole shaped leaves with a small hair-like root hanging on its underside. It resembles a four-leaf clover and is approximately the size of a pencil eraser. Frequently misidentified as algae, once established, it can cover the entire water surface and resemble a golf course green. It can cut off sunlight to submersed plants and cut off oxygen to fish and other wildlife. Read the article or check out the video below for more information and control methods.

Sonar Application Can Help Knock Out Duckweed

 by Scott Shuler

Duckweed is a small green free-floating plant that is fast growing and tends to form dense mats that often completely cover the surface of a pond.  Substantial growth from duckweed can cause big problems.  Apart from the simple fact that a full mat of green over a water feature lacks aesthetic appeal, the other costs of duckweed are substantial. With the entire body of water covered, duckweed prevents sunlight from getting into the water and causes low levels of oxygen and poor water quality – these conditions may lead to fish kills.  Duckweed can also impede water supply movement at intake points.

Long-term control for duckweed using Sonar® Genesis

As you determine your strategy for controlling duckweed, think long term.  Of the many SePRO management products available, a fluridone-based product such as Sonar® Genesis offers a good solution.  It is a fast-acting resource and allows you to often see results in less than four weeks.  You can gain control quickly and expect results for the remainder of the season.  Often, years of control can result from one treatment with a fluridone-based product.

A typical Sonar Genesis application includes an initial treatment in the spring and then small bump treatments three or four weeks later to maintain the proper concentration and control. Ideally, apply before the duckweed completely covers the water to ensure impact and results. Early in spring, watch for signs of growth and treat at rates of 30 to 60 parts per billion with a simple surface spray.

Rapid control of duckweed using Stingray®

Another option would be a product called Stingray® Aquatic Herbicide (active ingredient: carfentrazone-ethyl).  With Stingray, you will see significant results in 3 - 5 days. Stingray can be used alone or in combination with other systemic herbicides such as Sonar Genesis.

Control Methods

 by West Bishop (video)

In this short video, resident algae and plant expert West Bishop discusses a few common floating plants and then lists what solutions work best for chemical control.