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<http://www.promedmail.org>
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International Society for Infectious Diseases <http://www.isid.org>
[1] Date: Thu 28 Apr 2011
Source: The Indian Express [edited]
<http://www.indianexpress.com/news/Viral-disease-hits-muskmelon--growers-face-losses/782689/>
An outbreak of a viral disease has led to the muskmelon growers of Kapurthala and Jalandhar [districts] facing heavy losses. Farmers blamed private companies for selling them virus-infected seeds, without any check from the horticulture department.
The viral disease has affected over 2 dozen villages. It has led to deformed growth of the muskmelons, leaving them to rot on the field.
The farmers have faced estimated losses of 30 to 35 percent. The figure may increase as over 12 000 acres [about 4900 ha] of land are under muskmelon cultivation in the region.
When asked why the seeds sold by private companies are not checked, Dr Baaj Singh, Horticulture [department], said: "We have no such powers. Selling of spurious seeds can be checked by the state agriculture department. We are educating the farmers to check the further spread of the viral disease."
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[2] Date: Wed 27 April 2011
Source: IBN Live, Press Trust of India (PTI) report [edited] <http://ibnlive.in.com/generalnewsfeed/news/muskmelon-infected-by-diseases-in-punjab/663791.html>
Muskmelon crops in Punjab have been infected by diseases -- downy mildew and cucumber mosaic virus -- raising fear of extensive damage to the crop. Punjab Agricultural University [PAU] in its survey said muskmelon growing in areas of Jalandhar and Amritsar have been affected. "Both diseases have appeared in severe forms and could spread fast if appropriate control measures are not taken in time,"
PAU Plant Pathologist TS Thind said.
He said, in Amritsar district, cucumber crops have also been attacked by downy mildew. Muskmelon is an important cucurbit crop of Punjab and it is being grown in an area of 985 hectares [about 2400 acres] in the state. PAU experts said frequent rains and high relative humidity during the past days provided a suitable environment for the development of downy mildew disease.
Thind said that the cucumber mosaic virus is a seed borne viral disease. Apart from this, many weeds and cultivated cucurbits serve as source of the virus. When virus infected seed is sown, the seedlings exhibit symptoms of green and yellow patches on the leaves, he added.
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[Muskmelon (_Cucumis melo_) includes several subspecies and many cultivars, both with smooth (such as honeydew) and netted (such as subsp. _reticulatus_, rockmelon or cantaloupe) skins.
CMV
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_Cucumber mosaic virus_ (CMV) is found worldwide affecting a large number of hosts (around 190 recorded species) including many crops.
CMV exists in numerous strains, which may vary in their host range, symptoms, and means of transmission. In most hosts, it produces a systemic infection affecting newly formed tissues. For muskmelons, new leaves may wilt and die while older crown leaves may turn yellow then dry up, resulting in a slow decline of plant vigour and severe yield reduction.
CMV can be transmitted by more than 60 species of aphid vectors and can also be spread with infected plant material and very effectively by mechanical means (for example, during melon picking). Seed transmission to varying degrees has also been reported in 19 host species, including some weeds (which may act as pathogen and vector
reservoirs) and a few inbred lines of muskmelon. No information is provided above about the melon cultivars grown in Punjab and it appears that more information would be needed to verify the suspicion that the current outbreak is due to contaminated seeds.
Disease management for CMV is difficult since aphid vectors and virus reservoirs are widespread. Control of weeds surrounding cropped fields has shown some success. Host resistance is available in some crops but may only be effective against some of the virus strains.
A new strain of CMV has been reported previously to cause diseases of muskmelon in Punjab (Sharma et al. 1984, Phytopath. Z. 109, 332-40).
An outbreak of an undiagnosed virus was reported from Punjab in 2008 (ProMED-mail post 20080523.1695), but it is not clear whether this was caused by CMV since other viruses are also known to affect melons in the region (for example, _Zucchini yellow mosaic virus_, _Cucumber green mottle mosaic virus_).
Downy mildew
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Downy mildew caused by the fungus _Pseudoperonospora cubensis_ is a devastating disease of cucurbits. _P. cubensis_ is found worldwide, but it is usually most damaging in tropical and subtropical areas.
Different pathogen strains with variable host preferences (pathovars) seem to exist. By affecting the leaves and thus the photosynthetic potential of its host, downy mildew reduces yield and fruit quality, and it can eventually kill the host plant. If appropriate conditions are present, plantings can be infected so rapidly that they appear to have been frosted.
The fungus is an obligate parasite surviving on cultivated or wild cucurbits, and volunteer crop plants or cucurbit weeds may serve as sources of inoculum. The disease is spread by wind, rain splash, and mechanical means. Disease development can occur over a wide temperature range under conditions of high humidity. Control strategies include the use of resistant cultivars as well as applications of protectant and systemic fungicides.
Maps
India:
<http://www.globalsecurity.org/military/world/india/images/IndiaMap_tourism.gif>
and
<http://healthmap.org/r/006i>
Punjab districts:
<http://www.mapsofindia.com/print_image.php?id=http://www.mapsofindia.com/images2009/
printable_maps/punjab_district.gif&spid=undefined>
Pictures
CMV symptoms on cucurbits:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Cucurbit/CucViruses/
CucVirPhotoList.htm>
Electron microscopy of CMV particles:
<http://www.ictvdb.rothamsted.ac.uk/Images/Milne/cucumsv.htm>
Downy mildew symptoms on cucurbits via:
<http://cdm.ipmpipe.org/index.php?option=com_content&view=article&id=61&Itemid=70>
Links
CMV and other viruses of cucurbits:
<http://www.plantprotection.hu/modulok/angol/melon/cmv_mel.htm>,
<http://web.aces.uiuc.edu/vista/pdf_pubs/926.pdf>, and <http://vegetablemdonline.ppath.cornell.edu/factsheets/Viruses_Cucurbits.htm>
(with pictures)
CMV on cucurbits and other hosts:
<http://www.extento.hawaii.edu/kbase/crop/type/cucvir.htm>
CMV taxonomy and description:
<http://www.ictvdb.rothamsted.ac.uk/ICTVdB/00.010.0.04.001.htm>
Cucurbit downy mildew, disease information:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Cucurbits_Foliar.htm>,
<http://web.aces.uiuc.edu/vista/pdf_pubs/927.pdf>, and <http://www.avrdc.org/LC/cucurbits/downy.html>
_P. cubensis_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=120276>
PAU Agriculture:
<http://www.pau.edu/agriculture/>. - Mod.DHA]
[see also:
2010
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Murda, chilli & mildew, melon - India 20100413.1199
2009
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Banana viruses - Philippines (02): (CT) abaca ban 20091113.3926 Banana viruses - Philippines 20090204.0486
2008
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Undiagnosed virus, muskmelon - India: (PU) 20080523.1695 Cucumber mosaic virus, yams - West Africa 20080505.1533 Downy mildew, cucurbits - India: (PU) 20080411.1322
2007
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Downy mildew, cucurbits - USA: (SC), new strain 20071023.3448 Fungal diseases, vegetable crops - Canada: cucumber, potato
20070730.2442
Downy mildew, cucumber - USA (OH, MI), Canada (ON) 20070704.2120 and older items in the archives]
Topics
Species
