Floating Pondweeds

There are several different varieties of floating pondweeds; American or Longleaf Pondweed (Potamogeton nodosus), Illinois Pondweed (Potamogeton illinoensis), and Variable Leaf Pondweed (Potamogeton diversifolius), among others. They can be distinguished by having both floating and submerged leaves. The floating leaves are usually oval or blade-like, on long petioles. Submerged leaves are not abundant and are narrower and smaller than floating leaves. Fruits are on spikes that often stand above the water’s surface and are brownish to reddish or green. Floating pondweeds can become "topped-out," and a small light green seed head may be visible just above the surface at this time.

Floating pondweed growing at the water surface.

Management Options

Mechanical Options

Floating pondweeds can be controlled through cutting and raking, dyes, fertilizers, or barriers.

Mechanical treatment for aquatic vegetation

Biological Options

Grass carp will consume floating pondweeds and are excellent at controlling them.

Biological treatment for aquatic vegetation

Chemical Options

The active ingredients that have been successful in treating floating pondweeds include Bispyribac Sodium (G), Diquat (G), Endothall (E), Flumioxazin (G), Fluridone (E), Imazamox (E), Penoxsulam (F), and Copper Based + Diquat (G). E = excellent, G = good, F = fair.

Chemical treatment for aquatic vegetation

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