How Do I Treat Duckweed?
Tim - Rock Hall, MD
Duckweed is a very small floating plant about the size of a pencil eraser. It has shoe-sole shaped leaves with a small, hair-like root hanging below. Since duckweed floats on the surface of the pond, it is commonly mistaken for and treated as if it is algae. Unfortunately, algaecides have no effect on duckweed but there are a couple treatments you can do to keep the prolific duckweed at bay.
The Short-Term Solution
To treat duckweed as well as other aquatic weeds on a short-term basis, you can use Pondweed Defense® or RedWing™. Both are great for a one-time treatment or for spot treating. These are, however, only short-term solutions for duckweed. Due to their aggressive nature, duckweed can grow back in as little as 3 to 4 weeks. This is why we suggest a longer-term solution.
The Long-Term Solution
One of the only products on the market to provide long-term, season-long control of duckweed and other aquatic weeds is called WhiteCap™. Instead of having to spray the plant directly, WhiteCap™ is sprayed directly into the water. WhiteCap™ works by preventing photosynthesis in aquatic plants and by doing so causes them to slowly parish. Treating duckweed and other aquatic plants in this fashion allows for complete control of the entire water body for the season instead of just a few weeks.