Watermeal is a very tiny (less than 1 millimeter) light green free-floating, rootless plant. In fact, watermeals are the smallest seed-bearing plants in the world,. Watermeal tend to grow in dense colonies in quiet water, undisturbed by wave action. Often watermeal will be associated with colonies of duckweeds. Watermeal can be an aggressive invader of ponds and are often found mixed in with duckweeds or mosquito fern. If colonies cover the surface of the water, then oxygen depletions and fish kills can occur. These plants should be controlled before they cover the entire surface of the pond.
Dense colonies of water meal often can completely cover the surface of a pond and will cause dissolved oxygen depletions and fish kills These colonies will also eliminate submerged plants by blocking sunlight penetration. Watermeal is not known as an important food but many ducks may consume it and often transport it to other bodies of water.
Herbicide Management Options:
Clipper: is a flumioxazin product and comes in a water dispersible granule which must be mixed in water first and then either sprayed or injected. It is a broad spectrum, contact herbicide. Contact herbicides act quickly. Flumioxazin should be applied to actively growing plants and a surfactant will be needed if the herbicide is applied foliage of floating or emergent plants. Water pH needs to be below 8.5 or flumioxazin will rapidly degrade and lose effectiveness.
Sonar: is a fluridone compound, which comes in a liquid formulation, and has been effective on water meal. This is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.
Biological Management Options:
Tilapia: Will consume Duck Weed but are a warm water species that cannot survive in temperatures below 52 F. Therefore, Blue Tilapia usually cannot be stocked before mid-April and normally die in November or December. There are numerous reports of Blue Tilapia overwintering in mild South Carolina winters. Recommended stocking rates are 100 - 200 tilapia fingerlings per surface acre of plant biomass of mixed sex adult Blue Tilapia. Blue Tilapia is often not effective for vegetation control if the pond has a robust bass population due to intense predation. In South Carolina, stocking of Tilapia requires a permit from the South Carolina Department of Natural Resources. AMS is licensed to provide these permits for you.