| Potatoes
Stop PCN damage for even potato emergence
Potato Cyst Nematode feeding activity on potato crop roots can severely delay emergence and, in pest hot-spots, result
in patchy crops that never catch up, warns Syngenta Technical Manager, Douglas Dyas.
emonstrating the effects of
delayed emergence at Potatoes
in Practice near Dundee last
month (10 August 2017),
Douglas highlighted that even a
few days of difference in
emergence can have a lasting legacy on potato
crop productivity.
Rapid emergence assures the longest
possible growing season to achieve high
yields, whilst even emergence is important for
consistent tuber size and maturity at harvest, he
told visitors to PiP.
“Stronger root systems of crops protected
from PCN damage by Nemathorin nematicide
treatment would also be more efficient at
scavenging for soil moisture and fully utilising
fertiliser nutrients,” suggested Douglas.
“Rapid ground cover from a fast growing
crop can be extremely effective in suppressing
weeds and ensure the best possible results
from pre-emergence herbicide applications.”
Douglas pointed out that growers need to
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understand the differences between resistant
and tolerant potato varieties – and their relative
susceptibility to different PCN species.
“Tolerant varieties typically appear to be
better able to withstand the effects of PCN in
the field, but can still see large cyst populations
multiply by the end of the season - that will
affect future crops in the rotation,” he warned.
“Resistant varieties have been shown to reduce
the build-up of PCN populations, but crops will
be adversely affected during the growing
season and require nematicide treatment to
protect yield.”
Furthermore, Douglas reminded growers that
tolerant and resistant varieties can potentially
respond differently to the key PCN species,
Globodera pallida and G. rostochiensis. “The
later hatching and more difficult to control G.
pallida has tended to become a far greater
problem in recent years – which has been
largely attributed to the widespread growing of
Maris Piper that allowed the species to
proliferate.
“However, whilst soil sampling results has
shown most PCN populations are
predominantly G. pallida, growing a variety
exclusively resistant and/or tolerant to G.
pallida could still see G. rostochiensis resurface
as a serious issue.”
Douglas advocated that variety selection is
an important part of an Integrated Pest
Management of PCN and can be extremely
useful in utilising some fields where pest levels
would otherwise preclude economic growing.
“But in all instances, where the pest is a known
problem, they should be grown in combination
with Nemathorin for an effective long-term
strategy,” he advised.
“Key to that is soil testing to know the scale
of PCN threat before the crop goes into the
ground, ideally along with speciation of the soil
sample to understand the target and best
approach for control,” he added. Douglas used
the PiP demonstration to discuss techniques
and options to develop an effective IPM
approach to PCN management.
September 2017 | Farming Monthly | 27