Water Hyacinth (Eichhornia crassipes) is a State-declared Category 3 pest plant under the Biosecurity Act 2014. A Category 3 pest plant means that the species is already spread over substantial areas of Queensland, but its impact is so serious that it must be actively controlled to avoid further spread onto properties that are still free of the pest (Department of Employment, Economic Development and Innovation, 2011). It has recently been identified as a Weed of National Significance (WONS).
It grows from 10 centimetres to one metre tall when nutrient levels are high. It has showy, blue and white irregular flowers. Seeds may germinate in a few days or remain dormant for up to 25 years. The species is a major pest within waterways and its dense growth will reduce fish populations, limit food sources for waterfowl or provide shelter for mosquitoes (Sainty and Jacobs, 2003).
Management of Water Hyacinth currently relies on mechanical removal and application of registered herbicides. While biological control agents have been released in Australia, they cannot be relied upon to the same extent as Salvinia weevils. Biological control agents for Water Hyacinth have reduced plant vigour and flowering. However, the agents rarely build up to the high levels required to completely devastate the plant.
For further information regarding management of this species, visit the Queensland Government's Water Hyacinth page, or alternatively contact us on 07 5582 8211 or 1300 GOLD COAST.
Department of Employment, Economic Development and Innovation 2001, Declared plants of Queensland, The State of Queensland.
Sainty G.R. and. Jacobs S.W.L., 2003. Waterplants in Australia. Sainty and Associates Pty Ltd, Australia.