implementation of the aquatic Weeds of national ... - Weeds Australia

Alligator Weed
Cabomba
Salvinia
Significant limiting factors in the control of cabomba are the lack of biological controls and effective
herbicides. Physical removal (hand pulling or mechanical removal), shading, draining water bodies to
dry out the plant and heat treatment are the primary control methods currently employed. Research is
underway to find a biological control. There are also efforts underway to register another herbicide to
replace 2,4-D,nbutyl ester (the only effective herbicide), which had its registration suspended in 2005.
Nevertheless, many lessons have been learnt from management efforts in the NT and Qld infestations
as well as subsequent research under the Cabomba Strategy. A few large and strategic infestations are
now being managed under a management plan, such as the infestations in the Lake Benalla and Broken
River. A small infestation found in 2006 in a public park lake adjacent to the Murray River in Mildura, Vic.,
is under an eradication program: land managers have ‘drawn down’ (drained) the lake to dry out and
eradicate the weed. The lake will be refilled during 2009 and monitored for re-emerging cabomba.
Table A1.2 summarises management initiatives. Generally, however, the lack of good control methods has
inhibited the development of management plans.
Cabomba remains an extremely difficult weed to control. Although under development, there is as yet
no control manual to guide best practice. Managing the vectors of spread is crucial for cabomba, as is
managing public expectations of what can be achieved.
Salvinia
Although salvinia is a highly invasive aquatic plant with the potential to detrimentally impact waterways,
options for its control are relatively good.
Biological controls, herbicide use, physical control (removal and booms) are all quite successful – as
long as vigilance is maintained. Of the control methods available, the biological control provided by the
salvinia weevil (Cyrtobagous salviniae) has had the biggest impact, decimating extensive infestations in
northern parts of Australia.
A major thrust within the Salvinia Strategy has been
to ensure that the weevil can be extensively utilised
for control: research has shown that it is possible
to increase the geographical range of the weevils’
effectiveness; and plans to increase its availability are
being progressively implemented (see Note 6
or more details).
Inspecting plants for salvinia weevil
(Cyrtobagous salviniae) damage (NSW DPI)
Implementation of the Aquatic Weeds of National Significance Strategic Plans
Progress Report 2003-2008
16