A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
Date: Mon 13 Feb 2017
Source: PhysOrg, University of Cambridge report [edited] <https://phys.org/news/2017-02-cabbages-cowsincreasing-agricultural-yields-africa.html>
Cabbages have become a major cash crop for Ghanaian farmers. Recently, however, stunted, yellowing, wilting cabbages, their leaves curled, have become a devastating sight. 2 years ago [farmers] started reporting that a new disease was attacking their crops.
Ken Fening, University of Ghana, [says], "It seemed to be associated with massive infestations of aphids." Farmers were typically seeing the total loss of their crops and he realised that the devastation couldn't just be caused by insects. Despite no previous reports of viral diseases affecting cabbage crops in Ghana, the symptoms suggested a viral pathogen.
Fening began work with Cambridge's John Carr. "Aphids are a common carrier of viruses," explains Carr. "The 'usual suspects' are turnip mosaic virus and cauliflower mosaic virus, which affect cabbages in Europe and the US."
The virus was not what he expected, and work is now ongoing to identify the culprit. The sooner it can be characterised, the sooner strategies can be developed to prevent spread of the disease in Ghana, but also in the region.
--
Communicated by: ProMED-mail <promed@promedmail.org>
[_Cauliflower mosaic virus_ (CaMV; genus _Caulimovirus_) and _Turnip mosaic virus_ (TuMV; genus _Potyvirus_) affect crop, ornamental, and wild species of the family Brassicaceae (crucifers). Symptoms may include leaf mottling, necrosis and stunting of plants and can seriously affect crop yield and quality. Both viruses are spread by aphids and can be found in single or mixed infections, the latter leading to synergistic enhancement of symptoms.
There are a number of viruses affecting brassicas which are transmitted by aphids or by other sap-sucking insects (for example, whiteflies, thrips). Symptoms are not sufficient for diagnosis, as is being illustrated again in the report above. Presence of a particular virus in both host and vector has to be shown by molecular methods and pathogenicity studies to provide proof of association.
Disease management of aphid transmitted viruses is extremely difficult and may include vector control, removal of virus and vector reservoir hosts, phytosanitation to reduce inoculum (such as crop debris), use of clean planting material and resistant crop cultivars, if available.
Maps
Ghana:
<http://www.worldatlas.com/webimage/countrys/africa/lgcolor/ghcolor.htm>
and
<http://healthmap.org/promed/p/53>
Ghana regions:
<http://www.ghanaweb.com/GhanaHomePage/geography/region.php>
Pictures
Virus symptoms on cabbages:
<https://www.agric.wa.gov.au/sites/gateway/files/Figure%202.%20TuMV%20chinese%20cabbage.jpg>
(TuMV),
<http://www.foodsecurity.ac.uk/assets/images/releases/101118-crop-science3.jpg>
(TuMV),
<http://www.foodsecurity.ac.uk/assets/images/releases/101118-crop-science4.jpg>
(TuMV),
<http://c8.alamy.com/comp/BFXYH7/cauliflower-mosaic-virus-distortion-of-leaves-of-spring-cabbage-BFXYH7.jpg>
(CaMV),
<https://www.agric.wa.gov.au/sites/gateway/files/styles/original/public/CaMV_leaves.jpg?itok=HLD6-47o>
(CaMV), and via
<http://www.ipmimages.org/browse/Areathumb.cfm?area=122>
Links
Additional news stories:
<http://www.freshplaza.com/article/170851/Research-looks-to-fight-cabbage-disease-in-Ghana>
and
<http://news.foodmate.com/201702/news_51249.html>
Information on brassica viruses:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Viruses_Crucifers.htm>,
<https://www.agric.wa.gov.au/canola/virus-diseases-vegetable-brassica-crops?page=0%2C1>,
<http://bit.ly/2lYJpjt>,
<http://www.dpvweb.net/dpv/showdpv.php?dpvno=243> (CaMV), <http://www.dpvweb.net/dpv/showdpv.php?dpvno=008> (TuMV), via <http://ausveg.com.au/intranet/technical-insights/cropprotection/viral-diseases.htm>,
<http://www.clemson.edu/extension/hgic/pests/plant_pests/veg_fruit/hgic2202.html>,
and
<http://www.apsnet.org/publications/commonnames/Pages/Crucifers.aspx>
Virus taxonomy via:
<http://ictvonline.org/virusTaxonomy.asp?version=2015>
Insect vectors of plant viruses:
<https://projects.ncsu.edu/cals/course/ent425/text18/plantvectors.html>
List and taxonomy of _Brassica_ species:
<https://plants.usda.gov/java/ClassificationServlet?source=display&classid=BRASS2>
- Mod.DHA]
[See Also:
2015
----
Turnip yellows virus, oilseed rape - UK: survey
http://promedmail.org/post/20150612.3431867
2011
----
Vegetable viruses - Australia: (WA, QL)
http://promedmail.org/post/20110314.0817
2010
----
Turnip yellows virus, oilseed rape - UK: (England)
http://promedmail.org/post/20100227.0653
2006
----
Geminiviruses, vegetable crops - Jamaica
http://promedmail.org/post/20060310.0768
2005
----
Cauliflower mosaic virus, crucifers - Iran (Fars Prov.)
http://promedmail.org/post/20050607.1581
2004
----
Radish mosaic virus, crucifers - Iran: 1st report
http://promedmail.org/post/20040823.2349
2003
----
Turnip mosaic virus, pea - Spain (Almeria)
http://promedmail.org/post/20030109.0075
2001
----
Turnip mosaic virus, new hosts - Zimbabwe http://promedmail.org/post/20010921.2293]
Topics
Species
