Details of this species in Australia Status: Alien
Invasiveness: Invasive
Occurrence: Established
Source: Burton 2005 Arrival Date:
Introduction: Species Notes for this Location:
Water hyacinth currently occurs along the east coast of Australia from Kiama in NSW to southern Cape York Peninsula in Queensland. In the early 1900s dominant infestations in northern coastal rivers of NSW were a major hindrance to river navigation. In inland NSW, water hyacinth was identified on the Gingham Watercourse near Moree in 1955. By 1976 it had become a major infestation covering 7000 hectares, threatening the Murray-Darling system. These infestations are now under control but require annual monitoring and maintenance. Populations are also known to occur in Darwin, Perth, and the Mitchell River on western Cape York Peninsula, Mt Isa and Georgetown in Queensland. Infestations in Victoria and South Australia have been eradicated. It has never been found in the wild in Tasmania. Management Notes for this Location:
As part of a control program, nutrient run-off into infestations should be minimised. Heavy nutrient loadings in water come from erosion of cultivated land, cattle yards, domestic and municipal sewerage outfalls and wastewater discharges from factories. This nutrient inflow can be reduced or prevented by treating water before discharging it into waterways and using conservation farming techniques to divert cattle yard effluent and minimise soil erosion.
Users of agricultural (or veterinary) chemical products must always read the label and any permit before using the product, and must strictly comply with the directions on the label and the conditions of any permit. In NSW, numerous herbicides are registered for the control of water hyacinth. The most commonly used techniques for applying herbicides include: high volume spraying with knapsacks and power sprays, and boomspraying. Spraying an entire heavy infestation can cause water hyacinth to sink and result in pollution from the rotting weed. Large masses of the rotting weed will use all the oxygen in the water, killing fish and wildlife. This problem can be avoided by spraying strips or mechanically removing as much of the weed as possible prior to spraying.
Four insect species have been introduced from South America and released by CSIRO since 1975. There are two weevil species, Neochetina eichhorniae and N. bruchi, and two moth species, Niphograpta albiguttalis (previously Sameodes albiguttalis) and Xubida infusella. The weevil N. eichhorniae has been the most successful, playing a key role in destroying large water hyacinth infestations in tropical and temperate areas of Australia. The adult is black, 5 mm long, and feeds on leaves, making small scars. Eggs are laid in the bulbous leaf stalks and the larvae tunnel through the plant tissue, which is then attacked by bacteria and fungi. This causes the plant to become waterlogged and it can die under heavy attack. The lifecycle of N. eichhorniae takes three months but it is inactive during winter. The other weevil, N. bruchi, is active through the winter, and was first released in 1990 with seeming success. It appears that introducing both weevils is the best option, because of their lifecycles are complementary, but they are much less effective in subtropical and cooler areas. The moth N. albiguttalis is well established in northern NSW and Queensland. Its larvae tunnel into the petioles and buds in the same way as X. infusella, which was first released in 1981. New stocks of the latter were released by CSIRO in Queensland but its success is currently unknown. Both species are very damaging to young plants and luxuriant weed growth but their impact is often temporary and patchy.A biological control programme for Eichhornia crassipes was undertaken simultaneously with programmes for the other aquatic invaders Pistia stratiodes, Salvinia molesta and Hydrilla verticillata, to avoid the increase of other invasive species as one was controlled (Mack and Lonsdale, 2002). Last Modified: 4/08/2006 2:33:04 p.m.
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