Duckweed up close in hand with roots

Control Duckweed

Many people ask how to get rid of duckweed. The following options can be considered for how to control duckweed.


Manual/Mechanical Control:

If you are considering how to remove duckweed, physically seining this plant can be a somewhat effective method of control. However, physical control can be difficult. Duckweed can re-grow from any buds remaining in the water.


Herbicide Control:

There are multiple options for how to kill duckweed that offer great control.

  1. Dibrox (for ponds or lakes) – liquid that is diluted with water and sprayed over the plants, fast acting.
  2. Spritflo (for ponds with no outflow) – liquid that is poured and spreads throughout the entire body of water, offers extended control.
  3. Semera or Flumigard + surfactant (for ponds or lakes) – granules that are dissolved and mixed or liquids that are mixed and diluted with water and sprayed over the plants (early morning is best), fast acting.


When treating duckweed,

  • It is important to apply product evenly over all active plant growth; this plant can replicate rapidly from untreated or surviving plants.
  • Make sure you have identified the correct plant. Duckweed and watermeal are often confused. Proper identification can help save time, effort, and money.
  • Spritflo can be used at the first signs of growth.
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