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International Society for Infectious Diseases
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Date: Sun 29 Jul 2018 8:27 PM CEST
Source: The Telegraph [edited]
<https://www.telegraph.co.uk/news/2018/07/29/bordeaux-wines-ravaged-fungal-disease/>
Mildew is ravaging Bordeaux's vineyards [Nouvelle-Aquitaine region] in
France's largest wine-growing region. Few producers have been spared
from the outbreak which they say has been caused by heavy rainfall in
the spring [2018]. Most expect to lose between 20 and 70 per cent of
their crop.

Joel Ortiz, a producer who advises the local Chamber of Agriculture,
said: "Few vineyards are completely unaffected. It's widespread,
although it hits some varieties of grapes worse than others." Merlot
is most prone to mildew in organic vineyards, while cabernet sauvignon
is the worst affected non-organic variety. Even organic winemakers are
allowed to use copper as a preventive treatment, although the amounts
are restricted. 'Bordeaux mixture', which contains copper sulfate and
slaked lime, is most commonly applied but it is ineffective once fungi
have become established. If applied in large quantities year after
year, the copper can pollute the soil and other crops.

"We haven't had a series of disasters like this for decades," Mr
Verdier said. "It's a 7-day-a-week struggle. We remove mildewed leaves
to try to stop it spreading, then we apply the treatment, and then it
rains again. Once the grapes start taking on colour and ripening more,
the mildew should subside a bit, but the damage is already done."

[Byline: David Chazan]

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[There are 2 mildews of grapevine. Downy mildew (DM) is caused by the
fungus-like organism (oomycete) _Plasmopara viticola_. Symptoms
include lesions on leaves which later become necrotic. In years with
warm, extended wet periods during bloom, fruit clusters may be
partially or totally destroyed. Powdery mildew (PM) is caused by the
fungus _Erysiphe_ (previously _Uncinula_) _necator_. Leaves heavily
infected by PM have reduced photosynthetic ability resulting in
decreased plant vigour and increased chance of winter injury to the
vines.

Mildew spores are spread to the leaves and berries mainly by splashing
rain, wind or mechanical means. The fungi overwinter in infected
leaves on the ground. Mildew diseases on grapevine can be extremely
serious and will cause severe crop loss. They can be controlled with
fungicides, however, wet weather may interfere with fungicide
applications and fungal strains with fungicide resistances are
emerging.

Both mildews have been reported in the Bordeaux area before (for
example, ProMED-mail post http://promedmail.org/post/20070720.2323).
However, PM is favoured by warm temperatures and the absence of rain.
Since high rainfall is reported above to be the trigger for the mildew
outbreak, it appears more likely that DM is the cause.

Maps
France:
<https://image.shutterstock.com/z/stock-vector-france-political-map-with-capital-paris-national-borders-most-important-cities-and-rivers-218333659.jpg>
and
<http://healthmap.org/promed/p/6392>
France, regions:
<https://c8.alamy.com/comp/H4E06J/administrative-map-of-the-13-regions-of-france-since-2016-H4E06J.jpg>

Pictures
Downy mildew on grapevine:
<http://zabibu.files.wordpress.com/2007/02/mildew-downy.jpg> (leaf),
<http://web2.mendelu.cz/af_291_projekty2/vseo/files/9/1784.jpg>
(leaf),
<http://zabibu.files.wordpress.com/2007/02/downy-mildew-grapes.jpg>
(fruit), and
<http://www.inra.fr/hyp3/images/6034736.jpg> (flowers)
Powdery mildew on grapevine:
<http://www.inra.fr/hyp3/images/6037107.jpg> (fruit),
<http://midwestwinepress.com/wp-content/uploads/2011/07/Aug-16-2010-049-e1312058658136.jpeg>
(leaf), and
<http://www7.inra.fr/hyp3/images/6037101.jpg> (shoot)
_E. necator_ mycelium:
<http://www.inra.fr/hyp3/images/6037106.jpg>

Links
Information on downy mildew of grapevine (with pictures):
<http://www.inra.fr/hyp3/pathogene/6plavit.htm>,
<http://www.apsnet.org/edcenter/intropp/lessons/fungi/Oomycetes/Pages/DownyMildewGrape.aspx>,
and
<http://www.arec.vaes.vt.edu/alson-h-smith/grapes/pathology/extension/factsheets/downy-mildew-grapevines.pdf>
Information on grapevine powdery mildew:
<http://www.inra.fr/hyp3/pathogene/6uncnec.htm> and
<http://articles.extension.org/pages/31529/powdery-mildew-of-grapes>
Fungal taxonomy and synonyms via:
<http://www.indexfungorum.org/Names/Names.asp>
- Mod.DHA]

[See Also:
Downy mildew, grapevine - Cyprus: (PA)
http://promedmail.org/post/20180719.5914246
2015
----
Downy mildew, grapevine - India: (MH)
http://promedmail.org/post/20150716.3514732
2014
----
Fungal diseases, grapevine - Italy
http://promedmail.org/post/20140924.2799483
Powdery mildew, grapevine - Australia: (SA,VI)
http://promedmail.org/post/20140116.2176431
2012
----
Downy mildew, grapevine - India: (MH)
http://promedmail.org/post/20121012.1338526
2010
----
Downy mildew, grapevine - Australia (02): (VI, NS)
http://promedmail.org/post/20101205.4360
Downy mildew, grapevine - Australia: (SA)
http://promedmail.org/post/20101117.4164
Mildew & black rot, grapevine - Spain: (GA)
http://promedmail.org/post/20100705.2228
2009
----
Downy mildew, grapevine - Cyprus: (PA)
http://promedmail.org/post/20090720.2571
Downy mildew, grapevine - India:(MH)
http://promedmail.org/post/20090323.1138
2008
----
Downy mildews, maize, grapevine - India
http://promedmail.org/post/20081110.3537
Mildews, grapevine - USA: new strains
http://promedmail.org/post/20080327.1152
Fungal diseases, grapevine - Australia, South Africa
http://promedmail.org/post/20080310.0969
2007
----
Downy and powdery mildews, grapevine - France (02)
http://promedmail.org/post/20070724.2368
Downy & powdery mildews, grapevine - France
http://promedmail.org/post/20070720.2323
1998
----
Downy mildew disease, grapes - Australia (South West)
http://promedmail.org/post/19981031.2133]
.................................................sb/dha/mj/ml
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