Wednesday, July 11, 2018

PRO/PL> Silvering disease, sugar beet - Netherlands

SILVERING DISEASE, SUGAR BEET - NETHERLANDS
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Date: Wed 27 Jun 2018
Source: Vaaju [edited]
<https://vaaju.com/netherlandseng/rare-silver-disease-found-in-beet/>


The IRS [Dutch Institute of Sugar Beet Research] and knowledge centre
for sugar beet cultivation has received beet [samples] affected by
[the] rare silvering disease. Diagnostics have revealed beets [are]
affected. Beets with this syndrome have only been found sporadically
in the Netherlands. Beet growers in Belgium have been dealing with
silvering for a number of years.

The seed-borne bacterium _Curtobacterium flaccumfaciens_ pv. _betae_
causes the disease. The main symptoms are thick and brittle leaves.
Cracks are visible on the leaf and it tears easily. The leaves have a
matt-grey/silver-like reflection and the affected beets remain
[stunted] in growth. The vascular bundles in the roots are brown
discoloured. According to the IRS, there is no control measure against
this bacterium in the field.

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Communicated by:
ProMED-mail
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[Both _Curtobacterium flaccumfaciens_ (Cf) pv. _betae_ and Cf pv.
_beticola_ have been associated with silvering disease of beets (also
called bacterial tan or leaf spot when caused by pv. _betae_). It
affects vegetable and sugar beets (_Beta_ spp.), with up to 75 per
cent yield losses reported for some cultivars. Symptoms include a
silvery discolouration spreading through the leaves from mid growth
cycle onwards; systemic symptoms (such as leaf distortion, stunting of
plants) may occur, but generally root growth and development is more
obviously affected; finally the plant wilts and dies.

Cf strains and pathovars can be spread with seed, with an estimated
rate of 1 - 2 per cent in sugar beet for the silvering pathogens. Some
strains may survive for more than 20 years in stored seed and for at
least 2 winters in soil in the field. These bacteria are thought to
enter their hosts through wounds and consequently mechanical
transmission with cultivation activities poses a risk of transmission.
Disease management may include long crop rotations and
phytosanitation. Use of certified clean seed is paramount. Seed
pretreatments with antibiotics or hot water methods have been reported
to be effective in sugar beet to prevent silvering disease.

Cf pv. _flaccumfaciens_ can cause a serious wilt diseases in soybean
(_Glycine max_) and French bean (_Phaseolus vulgaris_), as well as
other _Phaseolus_ and _Vigna_ species. It has been reported to cause
total losses of bean crops and is considered a quarantineable organism
in many countries. It is moving northwards in Europe due to climate
warming (ProMED-mail post http://promedmail.org/post/20120809.1235745)
and the report above may reflect a similar shift for the silvering
pathogens.


Maps
Netherlands:
<http://www.ezilon.com/maps/images/europe/physical-map-of-Netherlands.gif>
Europe, overview:
<http://www.edinphoto.org.uk/0_MAPS/0_map_europe_political_2001_enlarged.jpg>

Pictures
Silvering disease on sugar beet (Cf _beticola_):
<https://www.researchgate.net/profile/Jian-Hua_Guo2/publication/249304766/figure/fig1/AS:298248007897100@1448119274947/Symptoms-of-sugar-beet-bacterial-leaf-spot-caused-by-the-new-pathovar-Curtobacterium.png>
C f _flaccumfaciens_ symptoms on beans, photo gallery:
<http://www.invasive.org/browse/subthumb.cfm?sub=11056>

Links
Original story (in Dutch):
<https://www.nieuweoogst.nu/nieuws/2018/06/27/zeldzame-zilverziekte-in-bieten-gevonden>
Information on silvering disease of beets:
<https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1744-7348.1961.tb03601.x>,
<https://bit.ly/2u6OHMo> and
<https://apsjournals.apsnet.org/doi/10.1094/PDIS-91-6-0677>
Cf pv. _betae_ taxonomy:
<https://www.uniprot.org/taxonomy/83664>
Cf pv. _beticola_ taxonomy:
<https://www.uniprot.org/taxonomy/221277>
C.f pv. _flaccumfaciens_ wilts on bean and soybean:
<http://www.plantmanagementnetwork.org/pub/php/brief/2007/drybean/>
Netherlands Institute of Sugar Beet Research (IRS):
<https://www.irs.nl/en>
- Mod.DHA

HealthMap/ProMED map available at:
Netherlands: <http://healthmap.org/promed/p/104>]

[See Also:
2012
----
Curtobacterium wilt, soybean - Germany: 1st rep, (TH)
http://promedmail.org/post/20120809.1235745
2006
---
Quarantine Pests, New Data - EPPO (02)
http://promedmail.org/post/20060531.1521
2005
----
Bacterial wilt, beans - Spain
http://promedmail.org/post/20051206.3515
2003
----
Plant pests, new data, EPPO http://promedmail.org/post/20030312.0608]
.................................................sb/dha/ao/ml
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