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[1] Honduras: 1st report
[2] Europe: 1st reports
[3] USA: updates
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[1] Honduras: 1st report
Date: June 2012
Source: European Plant Protection Organisation (EPPO) Reporting Service 6/2012/115 [edited] <http://archives.eppo.org/EPPOReporting/2012/Rse-1206.pdf>
1st report of '_Candidatus_ Liberibacter solanacearum' in Honduras
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In Honduras, heavy infestations of _Bactericera cockerelli_ were observed from 2006 to 2009 in commercial potato (_Solanum tuberosum_) fields in Santa Barbara Department. Affected plants showed interveinal chlorosis, vein-greening, downward leaf curling, stunting, above ground tuber formation and brownish flecks in some tubers. Disease incidence ranged between 50 to 95 percent. As these symptoms resembled those of zebra chip disease, leaf samples and psyllids were collected from 7 fields in 2 potato-growing regions and tested for the possible presence of '_Candidatus_ Liberibacter solanacearum' (EPPO Alert List). The latter was detected in 12 (out of 17) potato samples and in
7 (out of 10) psyllid specimens. This is the first time that '_Ca._ L.
solanacearum' was detected in Honduras. These results suggest that 'zebra chip' or a similar potato disease occurs in Honduras which may present a serious threat to potato production.
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[2] Europe: 1st reports
Date: June 2012
Source: European Plant Protection Organisation (EPPO) Reporting Service 6/2012/118-121 [edited] <http://archives.eppo.org/EPPOReporting/2012/Rse-1206.pdf>
1st report of '_Ca._ L. solanacearum' on carrots in Finland, in association with _Trioza apicalis_
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In 2008, carrot plants (_Daucus carota_) with symptoms resembling those caused by the carrot psyllid, _T. apicalis_ (Hemiptera:
Triozidae), were observed in 14 commercial fields in Finland. Affected plants showed leaf curling, yellow and purple discolouration of leaves, stunting of roots and shoots, and proliferation of secondary roots. Investigations revealed the presence of '_Ca._ L. solanacearum'
in diseased plants (including 1 asymptomatic plant). This is the first time that '_Ca._ L. solanacearum' is reported in Europe and also the first time that it is reported in association with a non-solanaceous plant. During these studies it was also found that '_Ca._ L.
solanacearum' could also be detected in mixed infections with Aster yellows phytoplasma in symptomatic carrot plants.
1st report of '_Ca._ L. solanacearum' on carrots in Sweden, in association with _T. apicalis_
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In 2011, carrot plants with symptoms resembling those caused by the carrot psyllid and '_Ca._ L. solanacearum' were observed in commercial fields in southern Sweden. Affected plants showed leaf curling, yellow and purple discoloration of leaves, stunting of roots and shoots, and proliferation of secondary roots. In the studied area, 70 percent of the fields were affected, with approximately 1 to 45 percent of plants per field being symptomatic. Carrot plant and pysllid samples were collected from diseased fields in the province of Halland and molecular tests detected the presence of '_Ca._ L. solanacearum' in plant (33 symptomatic and 4 asymptomatic) and psyllid samples.
Comparison of DNA sequences showed 100 percent similarity between the sequences of '_Ca._ L. solanacearum' obtained from Sweden and Finland.
This is the first time that '_Ca._ L. solanacearum' is reported from Sweden.
1st report of '_Ca._ L. solanacearum' on carrots in Norway, in association with _T. apicalis_
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In 2011, carrot plants with symptoms resembling those caused by _T.
apicalis_ and '_Ca._ L. solanacearum' were observed in commercial fields in southeastern Norway. Affected plants showed leaf curling, yellow and purple discoloration of leaves, stunting of roots and shoots, and proliferation of secondary roots. In the studied area, 70 to 80 percent of the commercial fields and experimental plots were affected, with approximately 10 to 100 percent of plants per field being symptomatic. Samples of carrot plants (petiole and root tissues) were collected from 5 fields which were infested by _T. apicalis_ in the counties of Ostfold, Vestfold, Oppland, and Hedmark. Molecular tests were performed on 54 plants (27 symptomatic and 27 asymptomatic) and detected the presence of '_Ca._ L. solanacearum' in 22 symptomatic and 5 asymptomatic plants. Comparison studies of DNA sequences showed
99-100 percent similarity between the sequences of '_Ca._ L.
solanacearum' obtained from Norway and Finland. This is the first time that '_Ca._ L. solanacearum' is reported from Norway.
1st report of '_Ca._ L. solanacearum' on carrots and celery in Spain, in association with _Bactericera trigonica_
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In Spain, the presence of '_Ca._ L. solanacearum' on carrot crops has recently been reported from the mainland and the island of Tenerife (Islas Canarias). The pathogen was also found in association with _B.
trigonica_, which was not previously reported as a potential psyllid vector. Symptoms were observed in several commercial carrot fields severely infested with psyllids (_Bactericera_ sp.) in the provinces of Alicante (18 fields -- approx. 62 ha [153 acres]) and Albacete (52 fields -- 297 ha [734 acres]) in the years 2008 to 2011. Molecular tests detected the presence of '_Ca._ L. solanacearum'. Comparison studies of DNA sequences showed a 97-99 percent similarity between the sequences of '_Ca._ L. solanacearum' obtained from Spain and Finland.
_Spiroplasma citri_ and Aster yellows phytoplasma was also detected in some samples. Commercial carrot fields in Tenerife (Islas Canarias,
Spain) showed symptoms and large populations of _B. trigonica_ were observed. Molecular tests detected the presence of '_Ca._ L.
solanacearum' in symptomatic carrot samples and psyllid samples.
Comparison studies of DNA sequences showed a 99 percent similarity between the sequences of '_Ca._ L. solanacearum' obtained from Tenerife and Finland, and 98 percent similarity with sequences obtained from tomato in New Zealand. Recently, the NPPO of Spain has confirmed the detection of '_Ca._ L. solanacearum' on carrot and celery (_Apium graveolens_) crops in the regions of Castilla La Mancha, Castilla Leon, and Comunidad Valenciana, as well as on carrot crops in Tenerife (Islas Canarias). Further diagnostic studies are still needed to confirm the identity of the pathogen.
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[3] USA: updates
Date: June 2012
Source: European Plant Protection Organisation (EPPO) Reporting Service 6/2012/116-117 [edited] <http://archives.eppo.org/EPPOReporting/2012/Rse-1206.pdf>
'_Ca._ L. solanacearum' detected on potatoes in Idaho, Oregon, and Washington
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In 2011, the occurrence of zebra chip disease of potatoes was observed for the 1st time in the states of Idaho, Oregon, and Washington (US).
The presence of '_Ca._ L. solanacearum' was detected in diseased tubers.
'_Ca._ L. solanacearum' detected on tomato plants in Texas
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The presence of '_Ca._ L. solanacearum' has been detected for the 1st time in field tomato plants (_Solanum lycopersicum_) in Texas. In 2008, 30 percent of tomato plants in several field plots showed yellowing, lateral stem dieback, upward leaf curling, enlargement of stems, adventitious roots, and swollen nodes.
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[Zebra chip (ZC) disease of potato was first reported in Mexico in
1994 and has caused yield losses of up to 60 percent in Guatemala, Mexico, and the southwestern USA. Symptoms include leaf yellowing, early senescence, and death of above ground plant parts, as well as necrotic flecking of tubers where starch is converted to soluble sugars. This results in zebra-like stripes and brittleness during processing. ZC leaf symptoms also resemble a group of symptoms known as psyllid yellows (PY), which was previously thought to be due to the injection of toxic saliva by the feeding insects.
In 2008, a new liberibacter species transmitted by potato (or tomato) psyllids (_Bactericera cockerelli_) was found to be associated with a new yellowing disease of tomato and capsicum crops in New Zealand (where the potato psyllid was first reported in 2006), as well as ZC and PY. The new pathogen was given the preliminary name of _Candidatus_ Liberibacter solanacearum (synonym _Ca._ L.
psyllaurous).
Only a few members of _Ca._ Liberibacter have been characterised so far, including the pathogens causing citrus greening (huanglongbing, HLB; more information via ProMED-mail post no. 20090415.1436). HLB, one of the most damaging diseases of citrus, is limited to these crops due to the host specificity of its vector, the citrus psyllid. In contrast, the potato psyllid has a wider host range including species in 20 plant families, and additional vector species for the new liberibacter are being reported above, further extending its potential host range. This impacts on the epidemiology and importance of the diseases due to _Ca._ L. solanacearum.
For both ZC and PY there remains a possibility that factors other than the liberibacter may be involved as well, for example, a possible role of phytoplasmas (as mentioned above) remains to be clarified.
Maps
Honduras:
<http://www.worldatlas.com/webimage/countrys/namerica/camerica/lgcolor/hncolor.htm>
Honduras departments:
<http://www.zonu.com/mapas_honduras/m_onu_hondurasx.htm>
Europe, overview:
<http://www.edinphoto.org.uk/0_MAPS/0_map_europe_political_2001_enlarged.jpg>
USA:
<http://www.mapsofworld.com/usa/usa-political-map.html>
Pictures
Psyllid yellows/ZC affected potato plants:
<http://www.forestryimages.org/images/3072x2048/1490010.jpg> and <http://www.ext.colostate.edu/PUBS/INSECT/insimg/05540F04_Web.jpg>
Processed ZC and healthy potato tubers:
<http://www.digitaljournal.com/img/4/2/9/0/i/4/1/7/o/8ab1aa702fece1872973ac17aec85b6f.jpg>
Potato psyllids:
<http://insects.tamu.edu/images/insects/common/images/a-txt/aimg91.html>
(adults) and
<http://www.insectimages.org/browse/detail.cfm?imgnum=1327131>
(immatures)
Links
Additional news stories:
<http://www.idahopress.com/news/state/devastating-zebra-chip-potato-pest-found-in-southern-idaho/article_804e467c-cb4c-5b8a-a66b-2ee9d979faa8.html>,
<http://www.heraldnet.com/article/20120705/NEWS03/707059842>,
<http://www.abc.net.au/rural/news/content/201207/s3540503.htm>,
<http://magicvalley.com/news/local/potato-disease-found-in-twin-falls-county/article_32dc49be-c536-11e1-8240-0019bb2963f4.html?comment_>,
<http://www.potatopro.com/Lists/News/DispForm.aspx?ID=7192>, and <http://www.capitalpress.com/idaho/JO-IdahoPsyllidsFound-062612>
Information on _Ca. Liberibacter solanacearum <http://www.eppo.int/QUARANTINE/Alert_List/bacteria/Liberibacter_psyllaurous.htm>
Information on potato zebra chip disease:
<http://panhandle.unl.edu/c/document_library/get_file?folderId=606641&name=DLFE-13907.pdf>
(with pictures) and
<http://www.digitaljournal.com/article/257488>
Information on potato psyllids:
<http://insects.tamu.edu/fieldguide/aimg91.html>
Genus _Ca._ Liberibacter taxonomy and species list:
<http://beta.uniprot.org/taxonomy/34019> and via <http://www.bacterio.cict.fr/candidatus.html>
EPPO alert list:
<http://www.eppo.int/QUARANTINE/Alert_List/alert_list.htm>. - Mod.DHA]
[see also:
2011
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Zebra chip, potato - USA, New Zealand: updates 20110915.2812
2009
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Liberibacter, solanaceous crops - multicountry 20090515.1819
2008
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Novel pathogens, tomato, potato - USA 20080820.2593 Liberibacter, solanaceous crops - New Zealand, USA 20080725.2269 Liberibacter, tomato & capsicum - New Zealand: new pathogen
20080604.1781
2007
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Zebra chip disease, potato - USA: research 20070530.1751]
Topics
Species
