Blackberry control manual - Weeds Australia

4.2 Physical control methods
The use of physical control methods alone
often gives poor results. Physical removal of
blackberry top growth will result in the death
of only the crown, even when the regrowth is
repeatedly removed for three to five years.
Combining a range of physical control methods
with the strategic use of herbicides is a more
reliable approach.
Hand and mechanical removal
Manual removal is generally not suitable in most
infestations. Seedlings and small plants are
difficult to pull out without breaking the roots.
Follow-up control and site rehabilitation are
essential if hand or mechanical weeding is used,
as regrowth from crowns, root fragments and
seed is inevitable.
Hand removal
Hand removal (removing the top growth of the
blackberry and digging up the roots) is most
suitable for small and isolated infestations.
Blackberry can produce root suckers from a
depth of at least 45 centimetres, so it is essential
to remove as much of the root system as
possible. The process is time consuming and
difficult but can be successful.
Grubbing
Mechanical grubbing is a good compromise that
is suitable for scattered infestations of mature
plants. With this method, whole blackberry
plants are removed by an implement attached to
a tractor, backhoe or excavator.
This technique completely removes the
infestation with relatively low site disturbance,
allowing immediate regeneration of the area.
Scalping
Scalping to a depth of 20 – 30 centimetres with
a root rake or similar equipment can be very
successful on accessible infestations. Care must
be taken to remove sufficient material to ensure
that the crowns and the majority of the roots are
removed.
Cultivation
Cultivation is the process of digging up or
cutting the soil to prepare a seed bed, control
weeds, aerate the soil, or work organic matter,
crop residues, or fertilisers into the soil. A
single cultivation can spread blackberry rather
than help control it, because root fragments
are distributed over the cultivated area. This
is usually the case if the cultivation is done in
winter.
Cultivation needs to be frequent and undertaken
at the appropriate time of the year (usually
summer) to achieve good control.
Consult your local weed management agency or
agronomic advisor before you cultivate. Consider
integrating cultivation options with other
blackberry management options.
Large earthmoving equipment
Using large earthmoving equipment may be
an option in specific situations. However, it is
unlikely that all root material will be removed,
and follow-up treatment with herbicides will be
required to achieve control.
Large earthmoving equipment can be used to cut
access tracks into large, dense infestations. Other
management options such as the use of herbicides
or grazing by goats can then be used successfully.
Slashing
Slashing should be considered only as a
short-term control method. It may be useful
in accessible areas to reduce plants to a
more manageable size or to open up dense
infestations for follow-up treatment using other
techniques.
Regular slashing on a fortnightly or monthly
basis encourages the blackberry to regrow and
use energy reserves stored in the root system.
This in turn may reduce the size and vigour of
the infestation. However, it is very expensive and
not very effective.
Irregular slashing can leave the plant with a
stronger root system and little top growth,
reducing the effectiveness of any follow-up
herbicide application. It may also stimulate
suckering, which increases the density of the
blackberry plants.
Before implementing a slashing operation,
consider the cost of labour and machinery and
the ongoing financial and time commitments
necessary.
57