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From: <promed-plant@promedmail.org>
Date: 9 February 2018 at 12:17
Subject: PRO/PL> Asian greening, citrus - China
To: promed-post@promedmail.org, promed-plant-post@promedmail. org

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[1]
Date: Mon 5 Feb 2018
Source: Fresh Plaza [edited]
<http://www.freshplaza.com/art icle/189031/Citrus-greening- disease-causes-drop-of-70- procent-80-procent-for-Gannan- Navel-orange>


Citrus greening disease caused a drop of 70-80 per cent for Gannan
[Gansu Province] navel oranges.. Since 2012, these areas have suffered
from a widespread outbreak of citrus greening disease.

China's major [citrus] production area has already moved north. The
main advantage is that the weather is relatively cold, which limits
the spread of citrus greening disease. Farmers have gradually deepened
their understanding of this disease. They are able to adopt effective
management.

The overall production volume is relatively stable. Government
departments continuously implement severe measures to restore
production areas that have suffered greatly from citrus greening
disease.

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

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[2]
Date: Tue 6 Feb 2018
Source: Xinhuanet [edited]
<http://www.xinhuanet.com/engl ish/2018-02/06/c_136953925.htm >

Across China, farmers fight against [a] global "citrus killer". Blood
orange growers in Lianjiang [Fujian province] have long ditched
chemical fertilizers to help their groves survive "the yellow dragon,"
a deadly disease threatening citrus groves. In China, the disease,
also known as Huanglongbing, wreaks havoc in more than 10
citrus-growing regions.

In 1993, a yellow dragon outbreak nearly exterminated blood orange
groves in Lianjiang, leaving only hundreds of hectares alive. Growers
spent more than 10 years recovering their groves to a total of 5000
hectares, but another epidemic in 2007 destroyed them again.

The government started subsidizing bacteria-free saplings produced by
a breeding center since 2010, because no one knew whether saplings
then traded in the market, all grown by farmers themselves, were clean
or not. Around 80 per cent of the cost of a bacteria-free sapling is
covered by the government. A farmer only needs to pay half the price
of a traditional sapling. The measures [also] include use of organic
fertilizers, equipment that captures psyllids, early detection and
handling of sick trees.

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Communicated by:
ProMED-mail
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[Greening is one of the most damaging diseases of citrus crops
affecting leaves and fruit. It is caused by fastidious
phloem-inhabiting bacteria classified as _Candidatus_ Liberibacter
asiaticus (Asian greening; huanglongbing, HLB), africanus (including a
subsp. capensis; African greening) or americanus (South American
greening). The 3 pathogens can only be distinguished by molecular
methods.

Symptoms include blotchy mottling and yellowing of leaves and small,
irregularly shaped fruits with a thick, pale peel and bad taste. Early
symptoms may be confused with nutrient deficiencies. Affected trees
become stunted, bear multiple off-season flowers and may live for only
a few years without ever bearing usable fruit.

The diseases are restricted to _Citrus_ and close relatives because of
the narrow host range of their psyllid vectors. _Ca._ L. asiaticus and
americanus are spread by the Asian citrus psyllid (_Diaphorina
citri_). The main vector for _Ca._ L. africanus is the African citrus
psyllid _Trioza erytreae_. The pathogens can also be spread by
grafting and possibly by seed from infected plants or transovarially
in the vectors. Both, pathogens and vectors, can be spread with plant
material.

Disease management requires an integrated approach including use of
clean planting and grafting stock, elimination of inoculum, use of
pesticides for vector control in orchards, and biological control of
vectors in non-crop reservoirs. Control using cultural methods, such
as interplanting with non-host crops, is being trialled. In areas
where a pathogen has not yet been detected, biological control of
vectors has been used successfully to reduce insect numbers and,
therefore, the risk of greening outbreaks (for example, see
ProMED-mail post http://promedmail.org/post/200 90601.2034).

Maps
China:
<http://www.beijing-travels.co m/image/chinamap.jpg>
China provinces:
<http://www.chinadiscovery.com /assets/images/customer-suppor t/maps/china-provinces-map- 600.jpg>

Pictures
Asian greening (HLB) symptoms, leaves and branches:
<http://www.delhidailynews.com /news_image/1402146122citrus- greening.jpg>,
<http://www.news.dm/wp-content /uploads/2012/10/citrus- greening.jpg>
and
<http://www.citrusalert..com/wp -content/uploads/2012/10/Green IslandsOfColor.jpg>
Asian greening, fruit symptoms:
<https://geneticliteracyprojec t.org/wp-content/uploads/2016/ 10/citrus_greening.jpg>,
<https://maxpull-tlu7l6lqiu.st ackpathdns.com/wp-content/uplo ads/2013/07/citrus-greening- 400x300.jpg>
and
<http://www.abc.net.au/reslib/ 200904/r362894_1677317.jpg>
Asian and African greening, symptoms and vector photo galleries:
<https://gd.eppo.int/taxon/LIB EAF/photos> and
<http://www.invasive.org/brows e/subinfo.cfm?sub=4695>
_D. citri_:
<https://entomologytoday.files .wordpress.com/2016/02/diaphor ina-citri-5006083-smpt-2.jpg? w=410>

Links
Citrus greening information:
<http://cisr.ucr.edu/citrus_gr eening.html>,
<https://www.daf.qld.gov.au/pl ants/health-pests-diseases/a- z-significant/citrus-greening- huanglongbing>,
<http://www.bioone.org/perlser v/?request=get-document&issn= 0015-4040&volume=087&issue=03& page=330>
and
<http://ecoport.org/ep?SearchT ype=slideshowViewSlide&slidesh owId=197>
Asian greening, information and distribution:
<http://www.cabi.org/isc/datas heet/16565>
African greening, information and distribution:
<http://www.cabi.org/isc/datas heet/16564>
Taxonomy of Liberibacter species via:
<http://www.uniprot.org/taxono my/34019>
Taxonomy and information for psyllid vectors (with pictures) via:
<http://www.psyllids.org/index .htm> and
<http://www.psyllids.org/psyll idsMorphology.htm>
 - Mod.DHA]

[See Also:
2017
----
Asian greening, citrus - Panama: 1st rep (BC)
http://promedmail.org/post/201 70707.5157200
Asian greening, citrus - Trinidad & Tobago: 1st rep
http://promedmail.org/post/201 70614.5104395
Asian greening, citrus - Mexico: (OA)
http://promedmail.org/post/201 70502.5007425
Asian greening, citrus - China: (southern)
http://promedmail.org/post/201 70120.4778384
2016
----
Asian greening, citrus - Nepal: (KS)
http://promedmail.org/post/201 61129.4660906
Asian greening, citrus - Tanzania: susp
http://promedmail.org/post/201 60912.4481387
Huanglongbing, citrus - Colombia: (LG)
http://promedmail.org/post/201 60209.4005503
2015
---
Huanglongbing, citrus - Portugal: (AL) susp.
http://promedmail.org/post/201 51116.3796582
Huanglongbing, citrus - India: survey
http://promedmail.org/post/201 50409.3285806
Huanglongbing vector, citrus - Europe: 1st rep, Spain (GA)
http://promedmail.org/post/201 50213.3163555
2013
---
Huanglongbing, citrus - Paraguay
http://promedmail.org/post/201 30724.1842707
2012
---
Huanglongbing, citrus - Brazil: (SP) update
http://promedmail.org/post/201 21114.1408468
Huanglongbing, citrus - Argentina: 1st rep, (MN)
http://promedmail.org/post/201 20917.1296650
Huanglongbing, citrus - USA: (CA)
http://promedmail.org/post/201 20404.1089672
Huanglongbing, citrus - USA: (TX) spread
http://promedmail.org/post/201 20122.1017941
and older items in the archives]
............................... ...................sb/dha/msp/ dk
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