•
POTATO SCIENCE LIVE
•
THE
VEGETABLE
FARMER •
MARCH 2017
presented this researchwork to
CUF, AHDB and ADAS, in 2016
British Sugar progressed to the
commercial strip trials stage.
According to Richard Cogman,
national LimeXmanager, LimeX
can offer real benefits in certain
situations depending on factors
including available Ca levels,
field history, varietal risk and
irrigation programme; for
example, in a field known to
have scab andwith a
susceptible premium variety
such as Maris Piper.
He stressed the importance of
knowing the soil Ca level and
urged growers tomeasure it
alongwith NPK and pH. “With a
Ca level below 2,000ppmwe
would expect to see a response
from applying LimeX at the pre-
planting stage,” he says. “Above
3000ppm and there is likely to
be no effect.”
He warned that pH is no
measure of available Ca. “While
applying LimeX before a potato
crop goes against the grain for
many farmers, we are starting
to get some traction to the
idea. We are getting positive
feedback from potato growers
with a range of soil types from
Wisbech series silts to sand land
soils.
“Before we started conducting
trials, anecdotally several larger
growers using Limex for club
root suppression commented on
a reduction in scab in
subsequent potato crops,” he
said. “The Ca is very quickly
available and doesn’t run out of
steam - LimeX offers exceptional
value for money.”
Trials applying LimeX pre-
potato crop have also shown
increases in dry matter. A trial at
Frampton saw dry matter up by
20-23%. In conclusionMr
Ecclestone said there was a
growing focus on Ca in a range
of crops while post storage
benefits were yet to be
evaluated. He urged potato
growers to test Ca levels in the
soil and to carry out strip trials
to see the effect on common
scab for themselves.
Controlling changing
late blight strains
While Syngenta’s
agrochemical range covers every
step of the potato crop− from
nematicides at planting to
herbicides and desiccation
products − technical
manager Douglas Dyas
chose to focus on the
late blight fungicide
Revus (and other
mandipropamid co-
formulations).
Phytophthora
infestans, the cause of
late blight, remains a
serious threat to potato
crops. Its evolving
pathogen population
continues to challenge
management practices.
Changes in P. infestans
populations are causing
late blight to affect
crops before weather conditions
would historically have
suggested they should, and
reduced fungicide sensitivity to
some actives has been observed
over a number of years.
“By implementing a full
fungicide programme growers
don’t tend to see problems,”
says Douglas Dyas, “but
applying in a preventative
manner is fundamental.”While
not wanting to put fear out
there, he said strain 37_A2 had
been observed in the UK in
2016 and, like 33_A2which
was also seen again, is reputedly
insensitive to fluazinam.
However, he saidwithout sexual
recombination these strains will
hopefully not become a
problem in commercial
scenarios where full fungicide
programs are used.
“According to data from the
Euroblight ‘league’ table of late
blight products, Revus is the top
performing product containing
a single active ingredient. It
scores 4 out of 5 for leaf blight
control and 3 (top score) for its
protectant properties and
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Douglas Dyas of Syngenta updated growers on
late blight fungicide Revus.
