Section 5 Case studies - Weeds Australia

Case Study 3
Controlling serrated tussock
without the use of herbicides
Summary
Controlling serrated tussock without the help of
herbicides brings special challenges but is not
impossible. This case study describes a number
of techniques Victorian organic farmers Len and
Geoff Menzel used with quite a degree of success.
Techniques include: increasing the fertility of the
soil, using rock and tree breaks to catch seed,
smothering and shading out seedlings, increasing
biodiversity, using crops and rotational grazing.
The problem
Len and Geoff Menzel bought their 365 ha
Victorian property near Geelong, Victoria in 1987
and have worked it to ensure organic certification
for their produce. In 1990 they discovered
serrated tussock in their west paddock, a 65 ha
block bordered by a rock fence.
The serrated tussock grew initially along the rock
fence, which caught seed borne on the prevailing
north-westerly winds. The weed then ballooned
in through a gateway spreading quickly over the
course of three years to cover more than 60% of
the paddock.
Len and Geoff were faced with a number of
problems: initially they did not know what the
weed was; as organic farmers, their option
to use herbicides as a means of control was
limited; cultivating the paddocks with plants
to out-compete serrated tussock would not
be successful until full scale serrated tussock
community action was enacted to reduce
reinvasion by seed rain.
Approach to the problem
Len and Geoff decided that the key to controlling
serrated tussock was to control “seed set”.
They decided on an integrated approach to
management, making immediate goals and
longer term ones—if possible they would gain
neighbour involvement.
In the short term their aim was to halt the spread
of the weed and then gradually reduce its level
of infestation. They wanted to at least achieve
a level of infestation where serrated tussock
did not dictate how the western paddock was
worked and could be managed by hand chipping
out individual plants.
In the long-term Len and Geoff aimed to have
zero serrated tussock on their land.
Key messages
• Stopping seed set of serrated tussock
requires an integrated approach.
• Attention to detail when implementing
the strategy is important.
• Maintaining good ground cover
vegetation is essential to discourage
serrated tussock from emerging.
• Clever strategies for controlling
serrated tussock may have
unexpected positive benefits for farm
profitability.
What has been done?
Cropping: At the beginning of their
management regime, Len and Geoff removed
sheep from the western paddocks most
susceptible to serrated tussock infestation
cultivated the land and sowed it with linseed
and, in rotation, spelt wheat. To keep up the level
of soil fertility, they under-sowed with triticale
and clover.
Len cultivates meticulously, noting that: “If you
drive too wide with a combine, you can create
more room for other weeds to come up.”
Rotational grazing: When cropping seems to
have substantially controlled serrated tussock,
Len and Geoff rotationally graze a herd of sheep
through three paddocks. Then, if the serrated
tussock re-invades, they remove the sheep and
re-crop the invaded paddock.
Buffer zones: To slow seed spread into their
land, Len and Geoff have set up a number of
buffers, using both rock breaks and plantations.
To make the land more amenable to cultivation,
they initially bulldozed rocks into rows. Then
in 1990 moved the rocks from the western and
eastern boundaries further into the paddocks to
form rock breaks. These rock breaks are between
400 m to 1000 m long and approximately 60 m
apart.
Along the three kilometre western boundary
of the paddock they also planted three rows of
pines and then a row of eucalypts. They planted
each tree in the row at about three-and-a-half
meter spacings. The width of the four rows is
about fifteen meters.
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