United Kingdom
July, 2008
Source:
Home-Grown
Cereals Authority (HGCA)
Research Review 69
Turnip yellows virus (TuYV) is probably the most important, yet
least understood, viral disease of oilseed rape in the United
Kingdom. It is possible that TuYV is one of the principal
reasons why commercial oilseed rape crops do not reach their
genetic yield potential. The virus is probably present
throughout the UK and at high levels in southern England. Virus
symptoms, which are not readily recognisable, are usually not
expressed before stem extension and can easily be confused with
other stress symptoms and nutritional deficiencies.
RR69 Turnip yellows virus (syn.
Beet western yellows virus), an emerging threat to European
oilseed rape production
by Mark Stevens, Graham McGrann and Bill Clark
Broom's Barn Research Centre, Higham, Bury St Edmunds
Suffolk IP28 6NP
June 2008
Summary
Nomenclature: The
International Committee for the Taxonomy of Viruses (ICTV)
approved the proposal to reclassify the European non-sugar
beet infecting strains of Beet western yellows virus (BWYV)
as an independent species within the genus Polerovirus, with
the name Turnip yellows virus (TuYV) being accepted. Recent
molecular evidence supported the separation of the
beet-infecting and non-beet infecting isolates as two
distinct viruses. European strains of Beet western yellows
virus (BWYV) that infect oilseed rape in the UK should now
be referred to as Turnip yellows virus(TuYV).
Turnip yellows virus (TuYV) is probably the most important,
yet least understood, viral disease of oilseed rape in the
United Kingdom. It is likely that TuYV is one of the
principal reasons why commercial oilseed rape crops do not
reach their genetic yield potential. The virus is probably
present throughout the UK and at high levels in southern
England. Virus symptoms, which are not readily recognisable,
are usually not expressed before stem extension and can
easily be confused with other stress symptoms and
nutritional deficiencies.
The main virus vector is the peach-potato aphid, Myzus
persicae. Annual sampling of M. persicae populations have
shown that up to 72% of winged M. persicae carry TuYV.
Studies in the 1980s and early 1990s showed that TuYV could
be widely present in oilseed rape crops throughout the UK.
Work at Broom's Barn Research Centre in the 90s showed that
TuYV could decrease yields by up to 26%. All yield
parameters including the number of primary branches, numbers
of seeds per pod and percentage oil per seed were affected;
the glucosinolate concentration in the oil was also
significantly increased in infected plants. Recent work in
Australia showed seed yield losses up to 46%. Estimates of
yield loss indicate that at an individual crop level,
control of TuYV could raise average yields from 3.3 t/ha to
between 4.4 and 6.0 t/ha. If only half of those losses could
be prevented (10-15%) by controlling TuYV, then the value of
the yield improvement would be in the order of £100-150/ha
(equivalent to £60-90 million per year to UK OSR growers).
Milder autumn and winter conditions favour the development
of the aphid vectors and encourage virus spread. Climate
change will exacerbate the situation as warmer conditions
will encourage the survival and multiplication of M.
persicae throughout the winter.
Strategies are required to decrease the impact of TuYV and
its aphid vectors on the yield of oilseed rape. Cultural
practices, seed treatments and foliar sprays provide an
opportunity to limit the impact of TuYV in a responsible and
sustainable manner. The levels of resistance to TuYV in
current UK varieties are not known. The identification and
exploitation of potential resistance genes provides an
alternative strategy to control this important viral
disease. Recent work in Germany identified a potential
resistance gene that could be exploited to provide
resistance to TuYV. Identification and exploitation of other
sources of resistance to TuYV are required.
HGCA Project Number: 3419
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