Duckweed and Watermeal: Identify and Control
Overview
Duckweed and watermeal are easily confused with one another. However, they can be properly identified by taking a closer look. Duckweed often has tiny, hair-like roots growing into the water, as well as 3 fronds that make it look a lot like a clover. In contrast, watermeal consists of small pieces that look like grains of sand and are the size of pinheads.
Often found together, both plants float and will grow anywhere across the U.S. in mainly still waters. Duckweed control involves multiple options of herbicides, while control of watermeal requires flumioxazin, which will effectively treat both weeds.
What Does Duckweed Look Like? Where Does it Grow?
It is important to know how to identify duckweed properly for correct treatment. The plant floats on the water’s surface and has roots 1/2 to 1 inch long hanging into the water below. It also has between 3 and 5 green, slightly curved, round fronds giving it a clover-like appearance. The fronds are 1/16 to 1/8 of an inch long, and the roots typically have 3-11 nerves.
Duckweed prefers stagnant, unmoving waters, and has the ability to double its numbers within a matter of days. It is found all over the U.S. – where there’s still water, there’s duckweed. This plant reproduces through flower buds that sink during the winter and come back up via air bubbles in the spring.
What Does Watermeal Look Like? Where Does it Grow?
Pinhead-sized, bright green plants swirling on the surface of the water is an unmistakable sign of watermeal. Each plant is round or oblong in shape, has no roots, microscopic flowers, and often gets mistaken for duckweed.
Watermeal loves still, nutrient-rich water, where it can grow very rapidly to cover an entire water body seemingly overnight. Watermeal thrives in every part of the U.S. just like duckweed. This plant reproduces through seeds, which will drop in the fall or winter and resurface in the spring.
Can You Have Both?
Absolutely. Watermeal and duckweed often accompany one another since they are similar and grow best in the same conditions. One of the most common ways for these plants to get into a water body is by being stuck on waterfowl or other animals that have just come from water where duckweed and/or watermeal are growing.
Since there will always be a risk of either plant beginning to grow, either from reproduction or animals reintroducing them, it is important to retreat regularly to maintain the quality of the water body.
Treatments
When it comes to duckweed control, Dibrox and Spritflo both offer effective results. While Dibrox is fast-acting, it’s also short term and must be reapplied more frequently. Spritflo takes longer to see results but lasts longer when used correctly and does not need to be reapplied as often. Both products will harm watermeal, however, neither of them will control it completely.
For effective watermeal control in ponds, Flumigard or Semera plus a surfactant is the best option. These are both flumioxazin products, which kills watermeal completely when applied correctly. In fact, flumioxazin will also control duckweed, so it is often used as the primary option when treating both duckweed and watermeal at the same time.
Conclusion
Proper identification is always an important step in the process of controlling weeds in a water body. Watermeal and duckweed each have unique characteristics that set them apart and can be helpful to determine which products are needed to treat them properly. Getting in touch with a professional may also be a critical step to saving time and money when controlling weeds.