Section 5 Case studies - Weeds Australia

Case Study 10
Serrated tussock strategy
pays off
Summary
A 20-year serrated tussock control program is
one of the factors that has helped Murray and
Barbara Stephenson double the carrying capacity
on their property ‘Brooklyn’, at Binda, near
Crookwell, NSW.
The problem
When Murray and Barbara Stephenson bought
the farm 25 years ago serrated tussock was
identified, but the extent of the problem was not
realised until five years later, when it had spread
rapidly across the 340-hectare property. It was
only then that they realised it was such a prolific
seeder, with new infestations rapidly occurring
downwind from existing stands, or on land
where soil had been disturbed.
The greatest impact of the serrated tussock
infestation was on the carrying capacity of
‘Brooklyn’. Where the weed was not controlled
in the past, Murray estimated there was a large
reduction in the stocking rate, as the weed
competed with both introduced and native
pastures. Today ‘Brooklyn’ carries 1700 Merino
and first cross ewes, producing 1700 lambs a
year.
The approach
Little information was available about control
methods when serrated tussock was first
recognised as a problem and the Stephensons’
approach was largely based on trial and error.
They originally wanted to achieve maximum
impact to control serrated tussock, and so their
first approach was to plough out the weed
from the worst-affected areas and introduce
improved pastures, including clover, cocksfoot
and ryegrass, in the hope that these would
out-compete serrated tussock. Unfortunately,
ploughing and cultivation encouraged the weed
to spread further and the pasture species could
not compete.
Murray and Barbara soon learnt that it was
necessary to treat the weeds with herbicide
during the pasture-establishment phase.
Serrated tussock also infests native pasture
on ‘Brooklyn’, and in these places Murray and
Barbara have relied on herbicide.
Key messages
• Be vigilant – watch for new serrated
tussock germinating and act quickly.
• Apply chemicals to serrated tussock
plants only – if spray affects the
surrounding pasture species,
their vigour and competitiveness
is reduced, thereby reducing the
effectiveness of weed control.
• Chemical concentration can be quite
low, and therefore cost-effective, if
spot spraying is undertaken at the
right time and applied correctly.
The Stephensons have undertaken two key
phases of the control program.
• For the first 15 years, they undertook
an intensive spot spraying and pastureimprovement
program, requiring about two
weeks of full-time labour each year. This
largely eradicated the larger patches of
serrated tussock and reduced the number of
new seedlings.
• Over the past five years, Murray and
Barbara have been able to scale down their
control program. Murray now spends only
two days a year spot-spraying any new
seedlings, with a focus on those parts of
the farm where the soil has been disturbed.
Their control strategy relies on herbicide
treatment, complemented with competitive
pastures. Cultivation is now used only to
establish improved pastures and not as a
tool for serrated tussock control.
The preferred method of control for serrated
tussock is the application of flupropanate, which
in Murray and Barbara’s experience has been
superior to glyphosate.
Murray and Barbara have learnt over time that
the key to success with herbicide is to allow
pastures to gain a competitive advantage over
the sprayed weed. They believe there are two
critical tactics to achieve this:
• spray serrated tussock when pasture species
(improved or native) are dormant
• spot-spray weeds to avoid chemical damage
to surrounding pastures.
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