Wildcat Connection September 2018 | Page 15

By Jeri Geren

In the heat of summer, many people find themselves drawn to cool and refreshing water. Often, this is either a swim at the lake or just sitting back and casting a line in their favorite fishing hole. Not only are mosquitos a pest, but it just isn’t near as fun to swim or fish when you are constantly fighting aquatic weeds. This time of year, aquatic plants tend to flourish in local ponds and water systems.

Although aquatic plants are a natural part of the aquatic ecosystem, they can often become too abundant and control efforts may need to be taken. When deciding to control aquatic weeds, the first step should be to identify the type of weed present, or at least correctly classify the plant. Aquatic weeds are classified into five categories. These include algae, floating plants, submerged plants, emersed plants and marginal plants. Knowing the correct classification of the plant will greatly aid control efforts if herbicides will be needed.

Algae: There are three major forms of fresh water algae. These include planktonic, filamentous and chara. Filamentous algae are the most commonly seen as a pest. It is characterizes by being either being slimy and green or producing a mat of “moss.” Algae is very easily controlled with copper algaecides.

Floating Plants: Floating plants can be difficult to control because many have the ability to reproduce very rapidly. Some plants are free floating and others are rooted at the bottom. Duckweed and watermeal look like small green seeds floating on the water surface. Mechanical control is often the best method for removal, if possible, to get all plants out of the water. Waterlilies and American lotus are also considered floating plants that have roots grounded at the bottom of the water system. These plants can be controlled with aquatic 2,4-D products and a variety of other herbicides that contain fluridone, glyphosate, imazapyr or triclopyr.

Submerged Plants: It may be tricky to control submerged plants with herbicides, because getting direct contact with the plant is more difficult since they remain submerged for most of their lifespan. Common submerged plants include pondweeds, watermilfoil and coontail. For excellent control of these weeds, look for products with the active ingredient diquat or fluridone.

Emersed Plants: These plants are rooted at the bottom but produce most of their leaves and flowers at or above the water surface. Common plants in this group include arrowhead, water primrose and waterwillow. For best control with herbicides, look for aquatic products containing 2,4-D or glyphosate.

Marginal Plants: Marginal plants are often seen around the pond edge. These are the ones growing in moist soil along the shoreline into water up to two feet in depth. Common marginal plants include cattails, reeds, sedges and smartweeds. For best control, look for products containing glyphosate, imazapyr or triclopyr.

It is important to keep in mind, that prevention and quick action will be the best lines of defense when it comes to aquatic weeds. Nutrient runoff and shallow water systems are major contributors to the growth of aquatic plant life. It is also key to remember that aquatic plants are part of the natural ecosystem and provide many benefits to surrounding aquatic life. Although it is nice when things look pretty, sometimes it is okay to have a few weeds. For more specific information, refer to K-State Research and Extension’s publication titled, “Aquatic Plants and Their Control.”