Reward Aquatic Herbicide to Control Duckweed in Ponds
Diquat, which is sold under the trade name of Reward is diluted in 50 to 150 gallons of water per acre and sprayed directly on the floating plants.
Diquat, which is sold under the trade name of Reward
, is used at 1 gallon per surface acre. Itis diluted in 50 to 150 gallons of water per acre and sprayed directly on the floating plants. Anonionic surfactant, which can be purchased at most places that sell Reward®, must be added to the Reward®/water solution as directed on the Reward label. A nonionic surfactant, which can be purchased at most places that sell Reward
Reward is a contact herbicide. That means it immediately causes the plant tissue it comes
into contact with to turn brown. Because duckweed and watermeal plants are so small, a single
Reward® treatment will seldom make contact with and kill all the plants. In addition, Reward® does
not persist in the water; it is typically gone from the water column by 7 to 10 days after treatment.
Therefore, any plants that survive the initial treatment will start to regrow in a few days. A typical
scenario after treatment with Reward® is that many of the plants will turn brown and sink but the
survivors will regrow and again cover the pond.
Several treatments of Reward® usually have to be made in a single season to keep a pond
relatively free of duckweed or watermeal. Treatments should begin as soon as the plants start to
grow in the spring or early summer in order to “keep ahead” of the growth. It is helpful to treat
when the wind has pushed the plants to one end of the pond; the spray should be concentrated on
the plants in that area. However, do not forget to spray small patches that may still be floating on
other parts of the pond or washed up along the banks.
Multiple treatments of Reward® can successfully control duckweed; unfortunately, they
seldom give effective control of watermeal.
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