Duckweed and Watermeal taking over..

Duckweed and watermeal are not the same.

Pond owners have been fighting for years to try to get rid of Duckweed,  but they  were really in for it when they started to get Watermeal growing on there pond.   So what is the difference, they look the same from 10 feet away..

Common duckweed is a very small light green free-floating, seed bearing plant. Duckweed has 1 to 3 leaves, or fronds, of 1/16 to 1/8 inch in length. A single root (or root-hair) protrudes from each frond. Duckweeds tend to grow in dense colonies in quiet water, undisturbed by wave action. Often more than one species of duckweed will be associated together in these colonies. Duckweeds can be aggressive invaders of ponds and will mix with other floating weeds like mosquito fern or watermeal.

If Duckweed becomes dense and covers the surface of the water, then oxygen depletions and fish kills can occur. This weed should be controlled before they cover the entire surface of the pond.

Duckweed colonies provide Habitat for micro invertebrates but if duckweed completely covers the surface of a pond for an extended period it will cause oxygen depletions. These colonies will also eliminate submerged plants by blocking sunlight penetration. Many kinds of ducks consume duckweed and often transport it to other bodies of water

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. Like duckweed 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.

Watermeal is also a very fast grower, one books said it double every 24 hours..”Doubles” so if you miss alittle of it on the side of your pond, you can rest assured that it will be back within a week… 

How do you control these problem weeds?

Mechanical removal:

Watermeal and Duckweed can be removed by ranking or seining it from the pond’s surface, but since watermeal is so small it is difficult to manage.  Watermeal will sink if the waters disturbed and then float back up when calm again making physical control tough.  Duckweed is easily controlled by using a Deskuzzer. 

Biological Control Options

Tilapia have been used to consume watermeal but are a warm water species so in many areas are not a viable alternative.  Grass carp will seldom control aquatic vegetation the first year they are stocked. Young grass carp will consume duckweeds but are usually not effective control as large fish (over 10 pounds).

Chemical Control Options

The active ingredients that have been successful in treating watermeal include flouridone.

The active ingredients that have been successful in treating duckweeds include diquat (G), fluridone (E), penoxsulam (E), and flumioxazin