HUTCHINSONS~FieldWise(October2018) (1) - Page 6

Probably the single most
important sprays applied in the
autumn, are those for grass weed
control. Over the years, grass
weed resistance has built up,
particularly to foliar sprays, such
that the key products for grass
weed control are soil applied, both
pre and early post emergence.
The first sprays in the autumn are
generally stale seed bed glyphosate
applications pre-drilling to control
grass weeds that have already
germinated. To maximise germination
of the grass weeds, a firm seedbed
is important, and double rolling is a
useful technique to be considered.
Two applications of 540g glyphosate
are recommended by Bayer at the
2-3 leaf stage of the black-grass with
cultivations between applications both
to kill any survivors and to promote
further germination. A third application
can be used if absolutely necessary,
however data has shown little benefit
from any further applications. Take
care not to exceed the maximum
total dose. Glyphosate works well at
reduced water volumes, 100 l/ha is
preferred. 2-3 leaf black-grass are
small vertical targets, the best nozzles
for hitting these are Hypro (Defy) 3Ds.
Image: courtesy of Sygenta
In a smooth seedbed the nozzle should
point forwards for maximum deposition.
In a cloddy seedbed, where the
weeds may be shaded by the clods, fit
them alternately forward and back. In
marginal conditions a Guardian Air drift
reducing nozzle is preferred and can be
partnered with a low drift glyphosate
formulation, such as Roundup Flex.
Pre- and Early Post-Emergence
Soil Applications
All spray applications are a
compromise. The ideal time for a preemergence spray is within 2 days of
drilling into a moist seed bed.
Spray Application
to Cereal Crops
in the Autumn
Tom Robinson (Independent
Applications Specialist) gives his
personal recommendations for
more effective grass weed control
this autumn.
This will get the best result from the
chemical applied. BASF recommend that
‘you shouldn’t drill, unless you can spray’,
while accepting the logistics of getting
the autumn work completed, may mean
applications to a seed bed that is drier
than ideal. Different products break down
at different rates, and behave differently
in varying soil conditions. Product advice
from your agronomist, can help optimise
weed control according to the prevailing
weather conditions.
The application goal is to get the
product as evenly distributed as possible
on the soil. The principal spoilers for this
include seedbed, wind, nozzle choice,
and sprayer set up. A smooth seed bed
is the ideal, but most autumn seedbeds
have clods, which because of the
forward speed of the sprayer, and wind
at the time of application, cause spray
shadows. The best way to overcome
the shadowing effect is with a purpose
designed nozzle. To my knowledge the
Hypro (Defy) 3D mounted alternately
forward and back is the best at this task.
When wind conditions are marginal,
one should use a drift reducing nozzle
such as the Hypro Guardian Air
75% drift reduction, or the Syngenta
recommended 90% drift reduction
nozzles such as the TeeJet TTI 110-05
(200 l/ha), and Lechler ID 120 -03 (100
l/ha). Over the past 3 years Syngenta
have seen improved weed control from
200 l/ha over 100 l/ha.
Iain Robertson
Stuart Kevis BASF
Barrie Hunt BAYER
James Thomas SYNGENTA
Post-Emergence Foliar
Optimum timing is 1-2 leaves of the
grass weed, at which stage the leaves
are vertical, 20-40 mm long and less
than 1mm across. The angled spray
from the Hypro (Defy) 3D will maximise
deposition on these tiny targets.
All nozzles pointing forward where
the seed bed is smooth, alternately
forward and back, where shading
from clods is likely. The higher the
water volume applied, the lower the
deposit of product on the target. 100
l/ha is the preferred water volume for
maximum deposition.
Sprayer Set Up
The key to success is a consistent nozzle
height of 50cm above the target. This
requires firstly, a straight and level boom,
secondly, boom isolation (suspension)
working optimally. Check the mechanical
isolation by depressing the boom end
down 30 cm. It should rise up above
the horizontal and settle in a horizontal
plane. Secondly, tyre pressure has a
huge effect on boom stability. Set the
tyre pressures to the minimum required
for the maximum load that each wheel
will carry. Keep the forward speed to
not more than 12 km/h.


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