While mechanical harvesting is a preferred option for most there are some restrictions.
For example Primrose Willow once fragmented can strike and proliferate as well as floating several kilometres and starting a new outbreak, this is typical for several aquatic weeds. This is where selective herbicides are now used to spray and eradicate the weed and after the herbicide has had sufficient time to effect control, (usually 5-7 days) the weed is then harvested and removed from the waterway.
Here is a brief list of prohibited or regionally controlled water weeds.
Egeria densa
Native to Brazil, dense waterweed (Egeria densa) has caused many problems overseas, particularly in the US. In Australia, it is a problem in a number of waterways where it is easily dispersed from broken stem pieces.
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Salvinia
Of the several species of salvinia that occur naturally in America, Europe and Asia, only one – Salvinia molesta, a native of Brazil – has become established in Australia.
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Cabomba
Cabomba (Cabomba spp.), or fanwort, is a fully submerged aquatic plant, originally introduced into Australia as an aquarium plant.
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Alligator weed
Alligator weed (Alternanthera philoxeroides) is regarded as one of the worst weeds in Australia because of its invasive tendencies.
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Anchored water hyacinth
anchored water hyacinth is an aquatic plant, native to tropical America. It is closely related to one of the world’s worst aquatic weeds, water hyacinth (Eichhornia crassipes).
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Longleaf primrose willow
An invasive aquatic weed threatening NSW waterways and wetlands Ludwigia longifolia can form dense colonies.
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Senegal tea plant
Senegal tea is a native of South America and was originally introduced into Australia as an aquarium plant.
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