Blackberry control manual - Weeds Australia

Herbicides at a glance
Five considerations when selecting a
herbicide
• Proximity of the application site to water.
• Selectivity of herbicide. It is best practice in weed
management to retain desirable species and
maintain groundcover.
• Cost of herbicide. Low-cost active ingredients
will not always give the best long-term control.
Application costs for retreatment need to be
factored into the decision.
• Level of control. Experience has shown that a
mixture of triclopyr + picloram +/– aminopyralid
will give the greatest long-term control.
• Application costs. For large infestations the cost
of retreatment is often underestimated.
Situations for specific herbicides
Metsulfuron-methyl. Recommended for initial
treatment of large, dense infestations.
Glyphosate. Recommended for small infestations
that are easy to check and retreat and areas where
other herbicides cannot be used, such as in or
near watercourses and in urban and peri-urban
areas.
Triclopyr. Recommended for initial treatment of
large infestations.
Picloram. Recommended where the use of pellet
formulations is considered the most appropriate
application technique.
Picloram + triclopyr. Recommended for most
infestations, both large and small, as it usually
provides the highest levels of control.
Relative herbicide costs
Lowest cost to highest cost at the highest
application rate – metsulfuron-methyl, triclopyr,
picloram, glyphosate, triclopyr + picloram,
triclopyr + picloram + aminopyralid.
Relative application costs
The cost for a contractor to apply herbicides can
be up to $1000 per day and more if the site is
difficult to access. One spray contractor said, Most
landholders focus on the cost of the herbicide
without thinking through the application costs.
Often it is far more economical to apply a higher
cost herbicide which will give a better long-term
result and minimise the time to come back with a
follow-up treatment of a less expensive and less
reliable herbicide.
Mixtures of active ingredients
The most common mixtures of the active
ingredients in Table 4.1 (p. 45) are:
• Picloram plus triclopyr (e.g. Grazon® DS,
Conqueror®)
This is the most reliable mixture of active
ingredients for the control of blackberry and
with correct application it will give the highest
level of control. This formulated mix has
recently come off patent and is now sold under
a number of different trade names.
Recently, aminopyralid has been added to the
triclopyr + picloram mix and is marketed as
Grazon® Extra. The manufacturer claims the
inclusion of the aminopyralid to the mixture
improves the efficacy on harder-to-control
blackberry.
Snapshot of picloram plus triclopyr mixtures:
• Higher cost, but this mix will provide the
highest level of control.
• MOA Group I.
• If herbicides other than Group I herbicides
have been used previously, allow two seasons
of regrowth before applying.
• With aerial application, Eucalyptus species up
to four metres tall can be killed; mature trees
15 – 20 metres tall may be party defoliated but
are likely to recover.
• Application to any native vegetation should
be done in accordance with State and local
regulations.
• Crop plant-back periods apply.
• Do not apply if rainfall is expected within
one hour of application.
• Expect reduced results if flooding occurs
within nine months of application.
• Grazon® Extra has a new label containing
information about managing residues that
may transfer from the pasture to the animal
and then to manure in livestock slaughtered
for export.
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