Oilseed rape growers can make
up time for the exceptionally cold slow start to spring, by
extending the growing season later in the summer. Crops which
have suffered from the icy blasts of northern winds are now two
to three weeks behind, but a 10-day green leaf extension from
Amistar application at flowering will be valuable in helping to
maximize total sunlight interception, according to
Syngenta Oilseed
Rape Crop Manager, Rod Burke.
ADAS trials last season have
shown that the strobilurin-effects of Amistar application
retains the all important green leaf area post-flowering,
encouraging plants to set more seed and to fill pods more
successfully. Additionally, it is the extra green leaf that is
believed to provide the energy source for a 0.85% increase in
seed oil content in Amistar treated crops, typically worth £7.50
per hectare oil bonus - over and above yield increases, reports
Mr Burke.
“Growers should assess crops to
see if they now really need a triazole for growth regulation -
it may be that the weather will have done sufficient and save
the cost of an early spring application.
“The key decision for growers
is when to apply Amistar. In low disease risk situations it can
be applied at the pre-flowering yellow bud stage, to maximise
green leaf retention and minimise damage during spraying,”
advises Mr Burke. “But where there is any risk of Sclerotinia,
application should still be made at the conventional early to
mid flowering stage.”
Eastern Counties agronomist,
David Parish of The Arable Group, reports that he will be
assessing oilseed rape crops over the coming weeks to decide
optimum fungicide strategy.
“We will look at the potential
Sclerotinia risk for each farm based on the history of disease
on the farm and the previous cropping, “adds Mr Parish. He
points out the risk is likely to increase with the greater area
of oilseed rape grown on many farms across the eastern counties,
the increase in min-till establishment - which leaves the
sclerotia near the soil surface - and the number of Sclerotinia
susceptible crops in the rotation, including spring beans, peas,
linseed, carrots and potatoes.
Mr Burke highlights results of
oilseed rape growers’ own split-field trials last year, where
applications from the yellow bud stage achieved average yield
increases of 0.35 t/ha in the absence of any disease. In high
disease pressure situations the flowering application was even
more effective, achieving average yield increases of 0.4 t/ha.
“The bottom line is that
Amistar pays and creates higher returns for growers, whether
disease strikes or not. They now have the flexible option to
target green leaf retention from an earlier application, or to
achieve the greater broad-spectrum disease control including
Sclerotinia and Alternaria from the flowering spray timing.”
