Elodea (Elodea canadensis)

Profile

Distribution

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

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.

Description

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: 

  • Egeria (Egeria densa): leaves in whorls of 4–5, crowded; larger flowers (2 cm wide) and leaves (4 cm long)
  • Hydrilla (Hydrilla verticillata): leaves in whorls of 3–8; larger leaves (up to 4 cm long), almost straight, serrated, dull green
  • Lagarosiphon (Lagarosiphon major): leaves in alternate spirals; curve downwards

Habitat

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.

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Control

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


Copper 110 g/L (Cupricide 110®)
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 (Reglone®)
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


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Legal requirements

Elodea (Elodea canadensis) is not declared in NSW under the Noxious Weeds Act 1993.

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Reviewed 2015