Blackberry control manual - Weeds Australia

Dome-shaped blackberry.
Example of a knapsack.
Tony Cook (NSW DPI)
Nathan Cutter (NSW DPI)
Low-volume application
Low-volume application may be required
where water availability and access by vehicles
and equipment is restricted. Several types of
spray applicators can be used for low volume
application, including:
• knapsack sprayers
• gas gun application
• control droplet applicators
• splatter gun.
With low-volume spraying the concentration
of the active ingredients has to be increased
to maintain efficacy. As with high-volume
application, correct calibration of equipment is
critical to ensure maximum herbicide efficacy.
Low‐volume spraying is done mainly by using
knapsacks that are pressurised manually. Some
labels recommend the same settings as with
hand guns. This is not realistic, as unpowered
knapsacks are not capable of delivering either
the same pressures or volumes as powered
hand guns. Low-volume spraying is suited to
smaller and less dense infestations of blackberry,
because large bushes require good wetting of the
inner canopy, a task that knapsack sprayers are
not designed for.
When spraying blackberry with a knapsack,
ensure the plant is lightly and evenly sprayed
so that foliage appears to have received a
moderate misting. Wetting to the point of runoff
when using a knapsack sprayer (low volume) is
excessive and defeats the purpose of low volume
spraying to use less water.
Tip: Low-volume spraying requires 10 times
the concentration of product and uses
¹∕₃ – ¹∕₅ of the water rate than high‐volume
spraying. In other words, the concentration
of active ingredient should be increased to
compensate for the reduced wetting of the
weeds. For example, if the high-volume rate
for triclopyr is 16 mL/10 L (or 160 mL/100 L
water), then the low‐volume rate would be
160 mL/10 L (or 1600 mL/100 L).
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