Weed all about - Department of Land Resource Management

Weed all about it
Issue 15 April 2012
Department of
Natural Resources,
Environment, The Arts
and Sport (NRETAS)
In this issue:
• Water mimosa alert in
Nhulunbuy
• Bellyache Bush
Assistance in the
Katherine region
• Alice athel on the way
out
• The Territory Wildlife
Park puts spotlight on
aquatic weeds
• Flea beetle attacking
mimosa on the
Adelaide River
• Launch of new weed
fi eld guide
Weed all about it
PO Box 496
Palmerston NT 0831
Ph: 08 8999 4567
Fax: 08 8999 4445
Biocontrol
Ph: 08 8999 2266
Email:
weedinfo.nretas@nt.gov.au
Website:
www.nt.gov.au/weeds
Water mimosa alert in Nhulunbuy
Water mimosa
(Neptunia plena), a
highly invasive, semiaquatic
weed with
touch sensitive leaves
has recently been
found in the ‘Town
Lagoon’ in Nhulunbuy.
Dhimurru Aboriginal
Corporation Rangers
discovered the weedy
outbreak and referred the
fi ndings to the NRETAS
Weed Management
Branch. Weed Offi cers
immediately coordinated
a management response
involving the Nhulunbuy
Corporation Limited and
the Rangers.
All water mimosa
plants have now been
successfully treated.
Monitoring of the lagoon
will now be a high priority,
and follow up control will
be likely.
Water mimosa can
establish and grow rapidly,
taking root in shallow
freshwater or forming vast
fl oating rafts.
Infestations can have
severe environmental
impacts including the
restriction of water fl ow,
reduced water quality and
biodiversity loss.
If water mimosa
were to spread into
freshwater environments
signifi cant impacts to
recreational fi shing
would be likely.
If you think you have
seen this weed, do not
attempt control yourself,
contact the Weed
Management Branch.
Water mimosa should
not be confused with
mimosa (Mimosa pigra),
an established fl oodplain
weed.
Water mimosa leaves.
Photo: Dhimurru Aboriginal Corp
Water mimosa fl ower.
Water mimosa infestation at ‘Town Lagoon’ prior to weed control being undertaken.
Photo: Dhimurru Aboriginal Corp
www.greeningnt.nt.gov.au

Bellyache Bush Assistance
in the Katherine region
Bellyache bush (Jatropha gossypiifolia) is one of the
most aggressive and poisonous weeds impacting
the dry tropics of northern Australia.
Bellyache bush forms dense thickets, excluding
pasture and other vegetation. It can take over
grazing land, reduce biodiversity and restrict access
for mustering. The fruit and seeds of bellyache bush
are also toxic to humans and animals if ingested.
A strategic approach will be required to achieve
effective management of bellyache bush across the
Katherine region.
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All land managers and owners have a responsibility
to take action and manage bellyache bush on their
properties. The Weed Management Branch is
coordinating the provision of a range of resources,
including herbicide, equipment loans and planning
advice, which should enable the implementation of
property-scale weed managment plans.
For further information contact Tahnee Thompson,
Regional Weed Management Offi cer, Katherine on
8973 8845.

Alice athel on the way out
Control work in Alice Springs had athel pine
(Tamarix aphylla), a Weed of National Signifi cance,
in its sights for local eradication this year.
The Alice Springs Landcare Group is working in
partnership with the Weed Management Branch
(WMB) to remove the last of the deliberately planted
athel pines from the town and surrounds to ensure
that the Todd River catchment is protected from
potential spread.
Funded by the Territory Natural Resource
Management Local Grants and the Australian
Government’s Community Action Grant programs,
seven of the last ten sites with athel pine have been
cleared by contractors and WMB staff since November
2011. Cut stump, stump grinding and dozing have
been used with debris burnt to prevent regrowth.
The remaining three sites are targeted for cut stump
treatment in April this year. These large trees, planted
in the 1940s for shade, will be a challenge to remove
without causing damage to surrounding buildings and
fences.
This program was established to support the
Territory 2030 target to eradicate athel pine from the
Territory (other than the Lower Finke River where the
target is for control). Treatment of athel pine in other
towns and communities has also commenced.
Successfully felled.
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Athel pine tree at the old Alice Springs
drive-in prior to cut stump treatment.
Loading the truck.

The Territory Wildlife Park puts the
spotlight on aquatic weeds
The Territory Wildlife Park recently displayed
several invasive aquatic weeds of the Top End, as
well as some native alternatives at the park.
To coincide with World Wetlands Day the Park placed
weeds, plants and educational resources on display
for the entire month of February. The display was well
received by members of the public, who were interested
in learning to differentiate the weeds and native plants
by viewing them at close range.
Weed educational resources.
The Territory Government has approved the
Weed Management Plans for:
• Prickly acacia (Acacia nilotica)
• Mesquite (Prosopis species) and
• Chinee apple (Ziziphus mauritiana)
These Plans form part of a strategic approach
to weed management in the Northern Territory
and will provide useful information to assist land
managers to control these weeds on their properties.
The overall aim of the Plans is to reduce the damage
caused by these thorny shrubs/trees in relation to
production, environmental and cultural values.
All landholders are now required to meet the
management objectives outlined in the Weed
Management Plans.
For more information or to request a copy of the
Plans visit www.nt.gov.au/weeds or contact the Weed
Management Branch on 8999 4567.
Park volunteers participated in a
community involvement day on Sunday
12 February assisting aquarium staff to set up a new
aquatic plant nursery. Weed Management Branch staff
also attended and spoke with volunteers, providing
information on aquatic weed identifi cation and weed
control programs currently taking place in the Top End.
It is hoped that the Park’s visitors are now better
equipped to report and/or manage these high priority
weeds.
Weeds on display included mimosa, salvinia and olive
hymenachne.
New Weed Management Plans
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Flea beetle attacking mimosa on the Adelaide River
Thousands of beetles are taking over mimosa
patches on the Adelaide River.
These tiny fl ea beetles are now swarming on
mimosa and will have an impact on reducing the
plants ability to produce seed. Although the area
currently covered by the fl ea beetle is small, the
potential benefi t of the fl ea beetles is very exciting.
The management of mimosa in the Top End
has included the use of biological control since
1983. The suite of insects and one rust that have
established in the region have greatly reduced the
output of seed and the weeds overall competitive
ability.
The mimosa fl ea beetle, Nesaecrepida infuscata,
is the fi nal agent in the mimosa biocontrol program.
Although identifi ed as a leaf feeder, the larvae of
this beetle will feed on seedlings and roots. The
adults are long lived which enables the population
to reach high numbers for long periods. As new
generations develop, the stresses infl icted by fl ea
beetles intensifi es. Beetles are increasingly able
to feed on new leaves produced in defence by the
mimosa plant.
N. infuscata was fi rst released in the Northern
Territory in 2007. Since then over 20 000 adults
have been released. Recent fi eld surveys
Close up upof of mimosa i fl flea ea beetle t
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indicate that the insect is now established on the
Adelaide River and showing potential to become
a damaging agent. The Weed Management
Branch’s commitment to biological control has
seen the number of insects produced in the
lab greatly increase. This has been one of the
contributing factors for the success of this agent
in the fi eld. It is anticipated that further fl ea beetle
releases will increase the chances they have of
surviving and increasing.
Biological control aims to reduce mimosa
reproduction and increase defoliation, particularly
on stand edges. These impacts then enable
grasses to out-compete mimosa seedlings.
Biocontrol is already contributing to the
integrated control of mimosa, a relationship which
the fl ea beetle will hopefully strengthen.
The Weed Management Branch will engage
land holders and rangers alike to help them
distribute this agent across the Territory later in
the year. This assistance should help to speed
up the spread and the impact that this tiny fl ea
beetle is having on mimosa in the Top End.
Leaf damage caused by the mimosa fl ea beetle.

Launch of new weed fi eld guide
The new book ‘Weeds of Northern Australia:
A fi eld guide’ by Nicholas Smith was recently
launched by the then Lord Mayor Graeme Sawyer
at the George Brown Darwin Botanic Gardens.
Hot off the press, this newly researched book
by prominent weeds expert Nicholas Smith and
publishers The Environment Centre NT, is an
invaluable tool to help land managers identify and
eradicate weeds.
This book is an essential fi eld resource for seasoned
land managers, those new to the issue of weed
management and even gardeners wanting to know if
plants growing in their garden are natives or weeds.
The fi eld guide features:
• Photos and descriptions for 150 weed species;
• Detailed descriptions for 90 high priority species;
• Species distribution maps;
• Detailed botanical drawings; and
• Information on identifi cation, fl owering and fruiting
time, preferred habitat, dispersal mechanisms
and recommended control methods.
Ben Stuckey, Nicholas Smith and Piers Barrow at the book launch.
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Weed information was provided by the NT, QLD
and WA Governments, including weed management
branches and Herbariums, the Department of
Agriculture, Fisheries and Forestry’s Northern
Australia Quarantine Strategy, pastoralists, land
management groups and Indigenous Rangers.
Copies are available for $25 each, from
bookstores across Northern Australia, or for
bulk orders of 10 or more, $20 each from the
Environment Centre NT.
Contact: Lisa Peters
Environment Centre NT Offi ce Manager
Ph: 08 8981 1984 or Email:admin@ecnt.org