Contact Us
University of California Cooperative Extension Ventura County
669 County Square Drive, Suite 100
Ventura, CA 93003
Phone: 805.645.1451
Fax: 805.645.1474
Office Hours:
Monday - Friday from 9 a.m. to 4 p.m.
The office will be closed for the following holidays:
March 29 – Ceaser Chavez Day
May 27 – Memorial Day
June 19 – Juneteenth
July 4 - Independence Day
Duckweed
Manual Control
Manual control involves physically removing the duckweeds or watermeal from the pond. Because of the explosive growth pattern of these small plants, few pond owners succeed in having manual removal solve their problem entirely. Best results are obtained if the owner regularly removes the duckweeds as they begin to become apparent. If attempted, it should be done on a day when wind has pushed the duckweeds to one side of the pond. Keep in mind that duckweeds thrive in protected ponds, so an owner may have to wait for a very windy day to try this. Once the duckweeds are pushed to one side, take a fine mesh dip net and start removing. Long-handled swimming pool nets work well. Remove as much as possible, and repeat the process as needed.
Chemical Control
Duckweed and watermeal can be controlled with herbicides although watermeal is much tougher to control than other duckweeds. Watermeal and duckweeds typically occur together, and the pond owner usually must plan his control based on watermeal recommendations. Chemical control is most effective if herbicides are applied early in the infestation, not once the pond has been covered with duckweeds. Regular walks around the pond can alert the owner to the first signs of duckweeds and watermeal. As always, be sure to read product labels for specific information on rates, application techniques, and safety.