Potatoes… - Bayer CropScience

From yield reduction to total yield
loss – pests such as the Colorado potato
beetle (Leptinotarsa decemlineata) and
aphids (e.g. Myzus persicae, Aulacorthum
solani, Macrosiphum euphorbiae), cicadas,
thrips, nematodes and potato moths are endemic
– and threatening – in almost all of
the traditional areas of potato cultivation.
The Colorado potato beetle and its larvae,
with their almost insatiable appetites, can
eat continuously and are capable of laying
waste to entire fields. In contrast, aphids
do not cause damage directly through their
feeding, but rather as so-called vectors of
viruses which they can transfer every time
they probe a plant with their proboscis. In
Europe alone, 20 virus types are recognised
– the potato leaf roll virus (PLRV),
potato virus Y (PVY) and X (PVX) are the
most important economically. The symptoms
of virus infection range from leaf
deformation and necroses through to
growth suppression and damage to the
tuber. Producers of seed potatoes must be
especially careful to prevent infection:
seed potatoes that carry viruses cannot be
certified for selling or sowing.
Safeguarding the
harvest is essential
“The potato is an expensive crop. Intensive
cultivation in Central Europe involves the
grower investing up to 3,000 Euro per
hectare“, says Bayer CropScience expert
Dr. Hartwig Dauck (Global Insecticides
Manager for potato). This sum covers the
costs for machinery, energy, work, soil,
seed, crop protection and fertilizing. He
continues: “If you want to avoid putting
this considerable investment at risk, you
have to keep an eye on pest insects right
from the start.“ Preventative measures are
urgently recommended, although their
influence on infection levels is limited. The
virus threat can be reduced by growing resistant
varieties in areas that are relatively
free of vectors, and long-term rotations can
also reduce the risk. But seasonal weather
is beyond the farmer’s control – if it is
favourable for the pests, then they will be
present in the field in larger numbers. This
is why it is essential to take steps to safeguard
yield and quality by applying the
right tools at the right time.
Consider damage thresholds
Damage thresholds are important considerations
in deciding on exactly the right
time to intervene: they indicate which
level of infestation can be tolerated
from an economic point
of view. Applying
Potato aphid (Macrosiphum solanifolii)
An overview of product
strengths:
Biscaya ® :
• Highly systemic insecticide with
long-term efficacy
• Active against sucking and biting
insects
• Pests living within the plant are
effectively controlled
• O-TEQ-formulation: rapid uptake,
increased rainfastness
• Can also be used at higher
temperatures
• Favourable profile towards the
environment and beneficials –
safe for bees
Proteus ® :
• Combination of active substances
with both systemic properties
and contact activity; more rapid
knock-down effect, but also longterm
activity
• Broad-spectrum activity against
sucking and biting insects
(including the potato moth)
• O-TEQ-formulation: rapid uptake,
increased rainfastness
control measures only makes sense if the
yield losses the pest is expected to cause
exceed the costs of protecting the yield
against the pest. Damage thresholds vary
from country to country – they also depend
on how the potatoes are to be used after
harvest. “In the United Kingdom, the first
aphid-control treatment in food and starch
potatoes is recommended as soon as the
aphid count reaches three to five per leaf.
If the number of aphids caught in traps
rises rapidly, reflecting a strong increase in
the population, it’s a first warning signal“,
says Dr. Dauck. “But seed potato growers
must take action as soon as the first aphid
is seen, otherwise they risk the virus-free
status – and thus the certification – of their
crop“. Depending on the region and local
climatic conditions, food potatoes need up
to four sprays and seed potatoes as many as
twelve sprays to cover the entire cultivation
period.
There are also strict requirements with
regard to the Colorado potato beetle: in the
Netherlands for example – where farmers
are actually legally obliged to control the
pest – treatment must start as soon as the
first larva has been found.
1/08 COURIER 23