Blackberry control manual - Weeds Australia

Avoidance of standard foliar applications could
be a valid option, particularly if the infestation is
rather small. In this case, permits may be granted
for cut-stump applications of herbicide, where
off-target risk is considerably lower. Describing
proposed risk controls in the application will
increase the likelihood of success. Recommended
risk-control measures include reducing hand‐gun
spray pressure (minimising drift), directing the
spray as much as possible away from water,
and avoiding spraying at times when the risk of
floods is high.
Ensure that an integrated approach to blackberry
management is proposed. Non-chemical
measures that suit this approach include grazing
with goats, burning dead canes, grubbing out old
crowns, introducing rust pathogens, providing
a competitive pasture and removing obstacles
such as logs that encourage the establishment of
blackberries.
If the permit application is to succeed, a logical
justification is required for an alternative
herbicide. As glyphosate is the main herbicide
registered for control in aquatic situations and
it does not result in acceptable levels of control,
it could be acceptable to use an alternative
product on the grounds of efficacy. The preferred
alternative herbicide to use near waterways is
metsulfuron-methyl. It has high levels of efficacy
whilst having relatively low aquatic toxicity
compared with other alternatives.
Metsulfuron-methyl has little adverse effect on
grasses, rushes and reeds but does kill ferns.
Established trees usually tolerate this herbicide,
provided that the foliage is not sprayed. Many
broad-leaved species that are oversprayed will
be damaged or killed. Aquatic species are rarely
affected under normal field-spraying conditions
at normal rates. Metsulfuron-methyl hydrolyses
quickly in water. However, a condition of the
permit may be monitoring of water quality to
ensure that any residues are below a standard.
The National Health and Medical Research
Council (NHMRC) have guidelines for health or
the Australian and New Zealand Environmental
and Conservation Council (ANZECC) have
guidelines for the environment.
Triclopyr is registered for blackberry control;
it is more selective than metsulfuron-methyl
and would be preferred in areas where ferns
or other species that would be damaged are
present. Its major drawback is that the registered
formulation is toxic to fish and it is relatively
persistent and mobile in soil.
A mixture of triclopyr + picloram + aminopyralid
has usually provided the best control. The
mixture rarely kills grasses (dependent on the
actual application rate, see ‘Type and rate of
herbicide used’, p. 43), although they may be
burned off after application, and it doesn’t affect
rushes, reeds and ferns. Broad-leaved weeds
and small trees that are oversprayed may be
damaged or killed. Most established trees will
not be affected, but some shallow-rooted species
may be damaged by the picloram component,
especially if their whole root zone is treated.
Furthermore, picloram is slightly to moderately
toxic to fish and other aquatic organisms. Due
to the adverse characteristics of the mixture, a
permit is more likely to be approved if limited
quantities are being applied on small or isolated
infestations or if the bulk of the infestation has
been controlled by other methods.
Herbicide application techniques
Most herbicides registered for blackberry
management are absorbed through the leaves
and canes. A few are taken up through the roots.
Following application directions as specified on
the label will ensure optimum herbicide uptake.
To ensure high levels of control with herbicides:
• correctly calibrate and maintain spray
equipment to ensure the herbicide is delivered
to the plants at the right rate (see Appendix 10)
• read publications and attend training days on
woody weed spraying and calibration
• read the label (particularly the critical
comments on the label).
The following techniques are the most
appropriate for applying herbicide to blackberry.
The one chosen will depend on the site,
equipment availability and infestation size.
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