Syngenta Summer Autumn Guide 2020 - Page 53



In high black-grass populations there may be an advantage to adding more
residual chemistry as a sequence to a stacked pre-emergence.
With all the same chemistry the sequence won by 2% in 2018/19, but
decision is more likely to be driven by drilling date:
Untreated
DRILLED BEFORE 15 OCTOBER
DRILLED AFTER 15 OCTOBER
Large stacks are more likely to
cause crop damage as early drilled
crops are softer. Sequences perform
well as grass weed emergence is
likely to occur over a longer period
of time.
Larger stacks are more suitable
as the number of opportunities for
following up diminish as winter
weather sets in.
TH
TH
Pre-em
AV Untreated = 120 heads/m2
Liberator 0.6 + DEFY® 3.0
Large pre-em stack
Liberator 0.6 + DEFY® 5.0 + Sunfire 0.24 + PDM 1200 g
Liberator 0.6 + DEFY® 3.0 fb PSC 2.0 + Sunfire 0.24 + PDM 1200 g
52
54
56
58
60
% control
62
64
66
Sequence
Source: Barton BG Innovation Centre 2019
WHERE BLACK-GRASS EMERGES FROM (DUE TO CULTIVATION METHOD) AFFECTS HERBICIDE PERFORMANCE
80
70
Av over Pre-em stack
Benefit to large stack = 9.75%
Benefit to Sequence = 12.5%
60
50
40
30
Sequence
Large stack
Pre-em stack
Sequence
Pre-em stack
Large stack
Direct Drill
Unt = 121 heads/m2
Sequence
Shallow (5 cm)
Unt = 189 heads/m2
Large stack
Min-till (14 cm)
Unt = 101 heads/m2
Sequence
0
Plough (27 cm)
Unt = 90 heads/m2
Large stack
10
Pre-em stack
20
Pre-em stack
However, in the high dormancy
year of 2016, seed on the surface
germinated over a longer period of
time, and there was an advantage to
sequencing herbicides, even in the
direct drill situation.
90
% control
In autumn 2018, leaving seed on the
surface or very close to the surface
helped with pre-em control. In this
low dormancy year, black-grass
seed germinated quickly and the
large stack was the best option
in a direct drilled situation. Where
weeds emerged from deeper due to
cultivations, they emerged over time
and therefore the sequence showed
an advantage over the large stack.
Pre-em Stack = Liberator 0.6 + DEFY 3.0
Large Stack = Liberator 0.6 + DEFY 5.0 + Sunfire 0.24 + PDM 1200 g
Sequence = Liberator 0.6 + DEFY 3.0 FB PSC 2.0 + Sunfire 0.24 + PDM 1200 g
Data is from the 2018/19 autumn season
53

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