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: Fri 22 May 2020 10:27:32 PM IST
Source: The Indian Express [edited]
<https://indianexpress.com/article/cities/pune/iihr-report-finds-a-plethora-of-viruses-behind-tomato-crop-loss-in-state-6422937/>
A variety of viruses are to blame for the ongoing early ripening of tomatoes in Maharashtra [ProMED-mail post http://promedmail.org/post/20200514.7337673], a report by the Indian Institute of Horticulture Research (IIHR) stated. Farmers reported early ripening, yellowing and distortion of fruits, which ultimately led to massive crop loss. Visual inspection had not shown any indication of pest attacks.
The Agriculture Department had sent samples to IIHR [which were] tested for 12 major viruses. They tested positive for _Cucumber mosaic virus_ (CMV), _Groundnut bud necrosis virus_ (GBNV), _Tomato leaf curl New Delhi virus_ (ToLCNDV), _Tobacco vein distorting virus_ (TVDV), _Tomato chlorosis virus_ (ToCV), and _Tomato mosaic virus_ (ToMV).
The report has recommended setting up a special investigation to study the problem in depth. Suhas Diwase, Agriculture Commissioner, said a special team of scientists will be constituted to come up with practices for tomato growers in the state.
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Communicated by: ProMED-mail <promed@promedmail.org>
[The viruses identified above and their main routes of transmission are:
_Cucumber mosaic virus_ (CMV; _Cucumovirus_), transmitted by more than 60 species of aphids;
_Groundnut bud necrosis virus_ (GBNV; _Tospovirus_), transmitted by thrips; _Tomato leaf curl New Delhi virus_ (ToLCNDV; _Begomovirus_), transmitted by white flies; _Tobacco vein distorting virus_ (TVDV; _Polerovirus_), transmitted by aphids; _Tomato chlorosis virus_ (ToCV; _Crinivirus_), transmitted by white flies; _Tomato mosaic virus_ (ToMV; _Tobamovirus_), no known specific insect vectors, transmitted by seed and mechanical means.
For more information on the viruses see links below and previous ProMED-mail posts in the archives.
It is not stated above whether multiple viruses were found in single samples, or whether different viruses were present in different plants, but in the scenario described, co-infections in at least some of the plants appear likely. Multiple viral or viroid infections are common in field plants with the potential for synergism (symbiotic enhancement of disease). If additional infections occur over a number of crop cycles, the virus population will gradually build up, both in number of co-infecting (possibly synergistic) virus species and in amounts of infectious units per virus species. This invariably leads to severely reduced plant vigour and a dramatic drop in yield.
For example, it is thought that combinations of various pathogens may have contributed to the general decline of citrus health in the region due to accumulation of parasitic pathogens in old orchards over time (see ProMED-mail post http://promedmail.org/post/20170109.4750640). A similar situation may have developed for tomato planting stock. Tomato seeds are traded widely and are known to pose a risk for spreading viruses and other pathogens (for example, ProMED-mail post http://promedmail.org/post/20140122.2222560). Use of certified clean seeds or tomato transplants is crucial and certification programmes for the crop would be needed to address the problems above.
Maps
India (with states):
<http://www.mapsofindia.com/maps/india/india-political-map.htm> and <http://healthmap.org/promed/p/310>
Maharashtra districts:
<http://www.mapsofindia.com/maps/maharashtra/maharashtra-district.htm>
Pictures
Symptoms of some tomato viruses via:
<http://www.ipmimages.org/browse/AreaSubs.cfm?area=63> and <https://ars.els-cdn.com/content/image/1-s2.0-B9780123943149000026-f02-01-9780123943149.jpg>
Links
Additional news story:
<https://www.hortidaily.com/article/9219921/india-tomatoes-in-maharashtra-infected-with-plethora-of-viruses/>
Information on some of the viruses above via:
<http://www.dpvweb.net/dpv/dpvnameidx.php>,
<https://www.sciencedirect.com/science/article/pii/B9780123943149000026>,
<https://extension.okstate.edu/fact-sheets/common-diseases-of-tomatoes-part-ii-diseases-caused-by-bacteria-viruses-and-nematodes.html#virus-diseases>,
<http://plantclinic.cornell.edu/factsheets/tomatoviruses.pdf>,
<https://www.rhs.org.uk/advice/profile?pid=250>, and <http://vegetablemdonline.ppath.cornell.edu/factsheets/Viruses_Tomato.htm>
International spread of tobamoviruses by seeds (review):
<https://www.researchgate.net/publication/321639141_Seed_Transmission_of_Tobamoviruses_Aspects_of_Global_Disease_Distribution>
Virus taxonomy via:
<https://talk.ictvonline.org/taxonomy/>
Information on plant virus vectors via:
<http://www.cals.ncsu.edu/course/ent425/text18/plantvectors.html>
IIHR:
<https://www.iihr.res.in/>
- Mod.DHA]
[See Also:
Undiagnosed disease, tomato - India: (MH)
http://promedmail.org/post/20200514.7337673
2018
----
Undiagnosed leaf curl virus, tomato seed - Egypt
http://promedmail.org/post/20181012.6086559
Cucumber mosaic & tomato spotted wilt viruses, capsicum - Europe:
(Balkan region) http://promedmail.org/post/20180914.6028544
Tomato chlorosis virus - Netherlands
http://promedmail.org/post/20180719.5914214
Leaf curl viruses, tomato & cucurbits - Italy: (SC)
http://promedmail.org/post/20180319.5697141
2017
----
Tomato leaf curl New Delhi virus, zucchini - Morocco: 1st rep (SS)
http://promedmail.org/post/20171206.5487792
Tomato leaf curl New Delhi virus, zucchini - Spain: (AN)
http://promedmail.org/post/20171114.5442041
Undiagnosed virus, tomato - India: (OR)
http://promedmail.org/post/20171103.5421613
2016
----
Tomato leaf curl virus, eggplant - India: (TN)
http://promedmail.org/post/20160415.4160915
2015
----
Vegetable viruses - Spain: (AN) alert
http://promedmail.org/post/20151204.3839034
Tomato mosaic virus - Israel: (Negev)
http://promedmail.org/post/20151015.3717154
2013
----
Yellow leaf curl & blights, tomato - Pakistan: (SD)
http://promedmail.org/post/20130206.1531086
2012
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Undiagnosed disease, tomato - India: (UT)
http://promedmail.org/post/20121213.1450713
2011
----
Undiagnosed virus, chili - India: (GA)
http://promedmail.org/post/20110408.1099
2010
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Tospovirus complex, tomato - Brazil
http://promedmail.org/post/20100719.2419
and additional items on tomato viruses in the archives]