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Date: Thu 8 Mar 2018
Source: Grainews [edited]
<https://www.grainews.ca/2018/ 03/08/zebra-chip-pathogen- detected-in-small-numbers-of- potato-psyllids/>

The zebra chip pathogen has been found for the 1st time in Western
Canada. University of Lethbridge's Dan Johnson [said that] so far,
_Candidatus_ Liberibacter solanacearum (Lso), the zebra chip pathogen,
has been detected in small numbers of potato psyllids -- the
pathogen's insect vector. But the pathogen has not yet been found in
any potato plant tissue. "There's no infection of potatoes, which is
good news. But it's likely to turn up," he says. Insects captured in
separate sites have tested positive for the pathogen, which may mean
there's a "widespread incidence of Lso at a very low level."

The discovery of the zebra chip pathogen is a game-changer for the
industry. A new 5 year program is being planned, "a very active
surveillance monitoring system to help potato growers make quick and
timely decisions." Its initial focus will be on tracking potato
psyllid numbers, as well as numbers of the insect's natural predators.
If producers suspect they've captured potato psyllids they should
contact provincial potato associations or agriculture departments and
get the insects tested for Lso.

[Byline: Julienne Isaacs]
--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[Zebra chip (ZC) disease of potato has caused yield losses of up to 60
per cent in parts of the Americas. 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
previously known as psyllid yellows. _Ca._ Liberibacter solanacearum
(Lso) was found to be associated with ZC of potato and has also been
associated with yellowing diseases of other solanaceous crops and some
crops in the family Apiaceae. Main vectors of Lso are the potato
psyllid (_Bactericera cockerelli_) in solanaceous host and carrot
psyllids (_Trioza apicalis_, _B. trigonica_) in Apiaceae.

The Lso species is divided into haplotypes: A and B affecting
Solanaceae; C, D, and E affecting Apiaceae. Both groups of haplotypes
have been reported from the Americas and New Zealand. Carrot
haplotypes only have been reported from several European countries,
northern Africa and the Middle East (see previous ProMED-mail posts in
the archives). Haplotype E was recently also detected in potatoes in
Spain [ProMED-mail post http://promedmail.org/post/ 20170802.5222241],
representing the 1st report of a haplotype being able to affect both
Apiaceae and Solanaceae, but it is unclear whether typical zebra chip
symptoms were observed in potatoes infected with haplotype E. More
research is needed on epidemiology, biology and distribution of Lso
worldwide.

Additional association of phytoplasmas with liberibacter diseases,
including Lso and the pathogens causing citrus greening (see previous
ProMED-mail posts in the archives) has been reported (see links
below). The role of each of the pathogens in symptom development and
epidemiology remains to be clarified.

The report above seems to be the first detection of Lso in Canada, but
it is not clear if the haplotype has been determined, or if the
perceived threat from ZC is based on the assumption that if the
pathogen was detected in the potato psyllid, it must be a potato
haplotype. Information on the haplotype(s) present in the country
would be important for risk assessment.

Maps
Canada (with states):
<http://www.lib.utexas..edu/ maps/americas/canada_pol_1986. gif> and
<http://healthmap.org/promed/ p/12>

Pictures
Zebra chip of potato:
<http://bit.ly/2FAgo7S> (Western Australia DPIRD, Agriculture and
Food),
<http://bit.ly/2lVfcQ6> (Western Australia DPIRD, Agriculture and
Food), and
<http://www.digitaljournal. com/img/4/2/9/0/i/4/1/7/o/ 8ab1aa702fece1872973ac17aec85b 6f.jpg>
(processed infected tuber, compared with healthy)
Lso symptoms on other hosts,
- carrot:
<http://journals.plos.org/ plosone/article/figure/image? size=medium&id=info:doi/10. 1371/journal.pone.0161016.g002 >
and
<https://gd.eppo.int/media/ data/taxon/L/LIBEPS/pics/ 1024x0/1939.jpg>
(compared with healthy)
- tomato:
<http://nwdistrict.ifas.ufl. edu/phag/files/2014/10/Fig-7- PY-Dufault.jpg>
and
<http://bit.ly/2HugMlb> (Western Australia DPIRD, Agriculture and
Food)
Lso photo gallery:
<https://gd.eppo.int/taxon/ LIBEPS/photos>
Potato psyllids:
<http://cisr.ucr.edu/blog/wp- content/uploads/2009/10/ potato_psyllid_04.jpg>
(adults) and
<http://www.insectimages.org/ browse/detail.cfm?imgnum= 1327131>
(immatures)

Links
Additional news stories:
<https://www.potatoesincanada. com/crop-protection/potato- psyllid-and-zebra-chip-update- 30070>
and
<https://www.producer.com/ 2017/10/zebra-chip-pathogen- makes-debut-in-alberta-potato- fields/>
Information on potato zebra chip disease:
<http://www.digitaljournal. com/article/257488> and
<http://link.springer.com/ article/10.1007/s10658-010- 9702-1/fulltext.html>
Information on _Ca._ Liberibacter solanacearum:
<http://www.eppo.int/ QUARANTINE/Alert_List/ bacteria/Liberibacter_ psyllaurous.htm>,
<http://onlinelibrary.wiley. com/doi/10.1111/epp.12043/pdf> ,
<http://www.cabi.org/isc/ datasheet/109434>,
<http://www.rhizobia.co.nz/ downloads/Weir_CS23.pdf>, and
<http://journals.plos.org/ plosone/article?id=10.1371/ journal.pone.0161016>
Lso haplotypes:
<http://link.springer.com/ article/10.1007/s10658-012- 0121-3/fulltext.html>
and
<http://bit.ly/2FMP9q4> (Australasian Plant Pathology Society)
Coinfections of liberibacter and phytoplasma species:
<http://www.fupress.net/index. php/pm/article/view/18683>,
<https://www. plantmanagementnetwork.org/ proceedings/irchlb/2008/ presentations/IRCHLB.4.4.pdf>,
<https://www.tandfonline.com/ doi/full/10.1080/http:// promedmail.org/post/07060661. 2016.1243586>,
<https://link.springer.com/ article/10..1007/s12600-012- 0225-5> and
<https://apsjournals.apsnet. org/doi/abs/10.1094/PHYTO-99- 3-0236>
_Ca._ L. solanacearum taxonomy:
<http://www.uniprot.org/ taxonomy/556287>
Information and resources for psyllids:
<http://www.psyllids.org/>
- Mod.DHA]

[See Also:
Liberibacter, carrot - Portugal: 1st rep
http://promedmail.org/post/ 20180129.5593290
Liberibacter solanacearum, parsley - Australia: 1st rep (NS)
http://promedmail.org/post/ 20180105.5538875
2017
----
Liberibacter, carrot - Greece: 1st rep (TC)
http://promedmail.org/post/ 20171112.5435078
Liberibacter solanacearum, potato - Spain: (CB)
http://promedmail.org/post/ 20170802.5222241
Liberibacter, carrot - Israel: 1st rep
http://promedmail.org/post/ 20170130.4803773
2016
---
Liberibacter, carrot - Sweden: (HA)
http://promedmail.org/post/ 20161130.4666613
2015
---
Liberibacter, carrot - Germany: 1st rep (NI)
http://promedmail.org/post/ 20151009.3702151
Liberibacter, solanaceous crops - Norfolk Island: 1st rep.
http://promedmail.org/post/ 20150417.3303297
2014
---
Liberibacter, carrot - Africa: 1st rep, Morocco
http://promedmail.org/post/ 20141121.2978030
2012
----
Liberibacter, vegetable crops - multicountry
http://promedmail.org/post/ 20120713.1199961
2011
----
Zebra chip, potato - USA, New Zealand: updates
http://promedmail.org/post/ 20110915.2812
and additional items in the archives]
................................ ...................sb/dha/mj/ dk
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