Elodea is found in slow-moving and stationary water bodies, coastal rivers and creeks, especially in colder areas in NSW, Vic and Tas. It has been a major problem in constructed waterways of northern Vic and south-western NSW.
Spread occurs by fragments. Elodea does not seed as only male flowers are found in Australia. Stems readily break into pieces which are easily transported in water.
Leaves are 0.5–1.5 cm long, 0.2–0.5 cm wide, and occur in whorls of 3 (rarely 4). They are bright green and bend down slightly.
Inconspicuous flowers occur on white thread-like stems, and have 3 petals. Only male flowers occur in Australia.
There are a number of similar looking species, including:
Elodea thrives in temperate zones, can withstand freezing and grows rapidly when temperatures exceed 15 °C. Elodea does not thrive in iron-deprived water and has a high light requirement for optimum growth.
See Using herbicides for more information.
Copper 110 g/L
Rate: 1 L per 10 cm water depth
Comments: Follow label directions.
Withholding period: Do not treat drinking waters used by livestock grazing on heliotrope or ragwort.
Herbicide group: n/a
Resistance risk: n/a
Diquat 200 g/L
Rate: 5 L /megalitre water
Comments: Apply by injection below the surface or as a surface spray.
Withholding period: 1 day in pasture, 10 days in treated water.
Herbicide group: L, Inhibitors of photosynthesis at photosystem I (PSI inhibitors)
Resistance risk: Moderate
Elodea (Elodea canadensis) is not declared in NSW under the Noxious Weeds Act 1993.