Paul from Cairo, Ga. writes
Diquat is labeled for duckweed but not for watermeal. Watermeal is a very difficult weed to get rid of and the only product we are aware of that will control watermeal is Sonar Aquatic Herbicide. You may want to reach out to your local cooperative extension office to see if they have any recommendations on what has worked for others in your area.
Answer last updated on: 01/03/2019