Section 5 Case studies - Weeds Australia
Section 5 Case studies - Weeds Australia
Section 5 Case studies - Weeds Australia
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Pasture management: The Alstons use a<br />
combination of rotational grazing and herbicide<br />
application to control serrated tussock in their<br />
pasture. They rotate sheep through the paddocks,<br />
allowing them to stay on a pasture until the less<br />
palatable tussock becomes more visible. They<br />
either spot spray of chip out single tussock plants:<br />
“We always keep a spray pack and mattock on our<br />
farm vehicles so we can get to the single plants.”<br />
On paddocks with denser infestations of serrated<br />
tussock, Tid and Sally originally attempted spot<br />
spraying but the exercise was too costly and time<br />
consuming. They now employ a contractor with<br />
a boom spray equipped tractor that uses a GPS<br />
guidance and mapping system to ensure accurate<br />
application. They have trialled using flupropanate<br />
alone as well as a mixture of flupropanate and<br />
glyphosate. They spot spray plants missed by the<br />
boom sprayer using flupropanate mixed with a<br />
marker dye.<br />
In addition, every three years—when fire<br />
restrictions allow—they burn paddocks with<br />
native pastures.<br />
In 2006, the Alstons had the more inaccessible<br />
areas of their property aerial sprayed with<br />
flupropanate.<br />
Shelterbelts: Tid and Sally have increased the<br />
size and density of existing exotic (pines and<br />
cypresses) and native trees shelterbelts and<br />
firebreaks to help prevent the spread of serrated<br />
tussock.<br />
Shelterbelts and firebreaks have been very successful in<br />
reducing serrated tussock seed spread.<br />
Results<br />
Cropping: Cropping is proving an effective<br />
method of controlling serrated tussock. The<br />
direct-drilling method rips small emerging tussock<br />
from the ground and the crop further provides<br />
strong competition against tussock re-emergence.<br />
Pasture management: Rotational grazing in the<br />
northern, originally heavily infested paddock has<br />
been successful. It now has a strong, competitive<br />
pasture cover.<br />
Grazing sheep in the more lightly tussock-infested<br />
paddocks is also proving a useful technique<br />
Charles Grech<br />
for helping to control the weed as long as the<br />
sheep are not allowed to overgraze. The grazing<br />
stimulates the growth of plants that compete with<br />
the serrated tussock.<br />
In addition, Tid and Sally are pleased with the<br />
results of periodically burning paddocks with<br />
native grass cover; desirable pasture species<br />
recover well after a fire and are able to outcompete<br />
emerging serrated tussock.<br />
The Alstons have learnt a number of lessons<br />
regarding herbicide application on pastures:<br />
• Timing of large scale applications is important.<br />
For example, if they fail to consider the<br />
slow rate of action and withholding period<br />
of flupropanate, spring pasture that could<br />
otherwise be utilised by sheep may go rank.<br />
Spraying, therefore, has to be considered as<br />
part of the overall grazing plan.<br />
• Using flupropanate alone rather than a<br />
mixture of glyphosate and flupropanate in the<br />
large scale spraying exercises seemed to have<br />
the best effect. Using the herbicides mixed<br />
killed both serrated tussock and desirable<br />
plant species that do not always recover well<br />
especially if the following season is dry. A<br />
flupropanate only application did result in the<br />
loss of some desirable pasture species but not<br />
as severely.<br />
• Aerial spraying produces mixed results. It was<br />
a quick way of covering a large inaccessible<br />
area in a short period. However: it was<br />
expensive due to the need for high water<br />
rates; timing of the spraying was restricted to<br />
contractor availability; there were logistical<br />
issues to overcome with the need to obtain<br />
flight path clearance and permits for chemical<br />
mixes; and the flupropanate application had<br />
the desired effect of slowly killing serrated<br />
tussock growth but also affected surrounding<br />
desirable species, resulting in less competition<br />
and the emergence of saffron thistles.<br />
Shelterbelts: The shelterbelts and firebreaks<br />
have restricted the spread of serrated tussock<br />
seed, with cypress being the most effective<br />
species in catching and suppressing seed spread.<br />
The future<br />
The Alstons believe that their strategy is working.<br />
Where possible, they will probably crop the<br />
paddocks that have re-emerging tussock to reduce<br />
tussock seed stock in the soil. They realise they<br />
will always have to control emerging weeds,<br />
whether tussock or thistles. The mattock and the<br />
spray pack will continue to be carried on their<br />
farm vehicles: “It’s an ongoing thing.”<br />
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