Section 5 Case studies - Weeds Australia

Case Study 4
Tackling serrated tussock on
steep intractable land
Summary
The strategic use of herbicides is a particularly
useful strategy when controlling serrated tussock
on steep intractable land. However, how and
which herbicides are applied depends on the
desired outcomes and on the level of off target
damage the land manager decides to tolerate.
This case study outlines the techniques and
concerns of two categories of land managers.
The first category are land managers concerned
with maintaining native species biodiversity
while attempting to control serrated tussock.
The second category of land managers are those
motivated to control serrated tussock to maintain
the profitability of their land.
The problem
Serrated tussock is difficult enough to control
on accessible land, but in steep, rocky or
deeply rutted landscapes, the problem is even
worse. Not only are these areas difficult to
access, they usually have the naturally sparse
grass cover associated with shallow soil or low
fertility that make them susceptible to serrated
tussock infestations. Failure to manage the
weed on intractable land, however, compounds
management issues on more accessible and
arable lands because of reinfestation by seed
blowing in from unmanaged areas.
Some of the most spectacular and highly visited
public reserves in Australia feature steep and
difficult terrain. Staff from the Parks and Wildlife
Group of the NSW Department of Environment
and Climate Change (DECC) know only too
well the problems of trying to manage serrated
tussock in such landscapes. For them, there is an
additional complication that they must control
the tussock while at the same time ensuring they
preserve native vegetation. These difficult areas
are frequently inaccessible even to the 4WD and
quad bike spray units DECC usually use.
Steep and intractable land is also a feature of
many privately held properties, such as the one
owned by John Hyles from the ACT. He has a
paddock bordering a 913 m escarpment with
a 200 m variation in elevation. Several years
ago, 65 ha in the escarpment paddock had a
monoculture of serrated tussock, with 10 ha
almost inaccessible country. Seed from serrated
tussock in the inaccessible area continually
reinfested John’s property. Unlike staff from
DECC, John’s primary concern is to run a
Key messages
• Both vegetation type and terrain
dictate which serrated tussock control
techniques are most appropriate.
• Regardless of method of application,
accuracy of herbicide application
and application rate are vital. This is
especially the case when using aerial
spraying.
• Regardless of techniques used for
control, it is important to ensure that
areas cleared of serrated tussock are
revegetated.
• Aerial application of label rate
flupropanate may be appropriate and
cost effective for control of serrated
tussock in steep intractable land
dominated by exotic grass species. It
is not appropriate for areas dominated
by native grass species.
• In some situations, unproductive
farming land infested with serrated
tussock should be returned to native
bushland.
profitable agricultural enterprises rather than
manage for the conservation of native fauna and
flora.
The approaches
Spot spraying: The method used by DECC on
steep intractable land is application of herbicide
from spray units mounted on 6WD Polaris
Rangers. These vehicles have a lower centre
of gravity than a quad bike and can cope with
steeper slopes. DECC mounts Quickspray units
with extension hoses up to 100 m long on the
Polaris Rangers (more hose lengths can be added
if required). Where land is too steep and difficult
even for the Polaris Rangers, staff use portable
spray units, such as knapsack sprayers, Polaris
Rangers are also used to support staff carrying
backpack spray equipment by carrying water and
other essential equipment.
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