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Date: Mon 26 Aug 2007
Source: New Kerala [edited]
<http://www.newkerala.com/july.php?action=fullnews&id=56135>

Pulse crops such as urdbean, mungbean, and soybean in Punjab have come under attack of whiteflies, an insect pest. The attack has been witnessed in all the pulse-growing areas of the state, a Punjab Agricultural University (PAU) press release stated today [26 Aug 2007]. This insect has appeared in epidemic form due to the hot weather conditions coupled with dry monsoon spell prevailing in the state over the last few weeks. Such weather conditions are extremely conducive for the rapid multiplication of the pest.

According to Dr N S Buttar, Head, Department of Entomology, PAU [Punjab Agricultural University], whitefly feeds on the leaves of the plants by sucking the cell sap and excretes honey dew on the plants, on which the growth of sooty mould takes place, resulting in the blackening of leaves and decreases in the normal photosynthesis. In case of severe attack, there is total blackening of the crop, resulting in drying of leaves and ultimately, total crop failure.
Whitefly is also a vector of serious viral disease -- mungbean yellow mosaic --, which is a limiting factor in the successful cultivation of these crops.

Dr Buttar has advised the farmers not to get panicky and to spray the crop with the recommended insecticides.

--
Communicated by:
J. Allan Dodds
Former ProMED-mail plant disease moderator <dodds@ucr.edu>

[_Mungbean yellow mosaic virus_ (MYMV; genus _Begomovirus_, family
_Geminiviridae_) is endemic to South Asia. A number of strains have been isolated from different hosts and locations (India, Thailand, Philippines).

_Mungbean yellow mosaic India virus_ (MYMIV) has now been classified as a distinct species. It is the most serious problem of mungbean in the Indian subcontinent (India, Pakistan, Nepal, Bangladesh) and also affects other leguminous crops such as soybean, cowpea, pidgeonpea, and black gram. Infected plants become chlorotic and stunted, and yield losses of up to 100 percent have been reported in severely affected crops. MYMIV is transmitted by whiteflies (_Bemisia tabaci_) in a non-persistent manner, meaning that vector insects remain infective for a period of time after acquisition of the virus. MYMIV is not transmitted by mechanical inoculation, seed, or pollen.
Disease management includes vector control (insecticides, weed control) and the use of resistant host varieties.

Interaction between MYMIV and a satellite DNA has been reported resulting in even more severe symptoms than infection by the virus alone. _Begomovirus_-satellite disease complexes have been found to cause economically important diseases in a range of crops and pose a serious threat to tropical and sub- tropical agriculture worldwide.

It is not stated in this report whether MYMIV symptoms have already been observed in the region. Since the virus is rife in northern India, potential sources of inoculum for the vector insects may be expected to be available, and dispersal (for example by wind, plant material, human movement) of insects carrying the virus would be likely. Once a local source of MYMIV is available, spread throughout the regional crops will be very fast given the large numbers of vector insects present.

Maps
India:
<http://www.globalsecurity.org/military/world/india/images/IndiaMap_tourism.gif>
Punjab:
<http://www.mapsofindia.com/maps/punjab/punjabroads.htm>

Pictures
MYMV leaf symptoms on mungbean:
<http://www.avrdc.org/LC/mungbean/production/diseasepix05.html>  and <http://www.bspp.org.uk/ndr/july2004/2004-18-1.jpg>
Comparison of MYMV symptoms in susceptible and resistant mungbean varieties:
<http://www.avrdc.org/LC/mungbean/production/diseasepix06.html>
_Begomovirus_ particles, electron micrograph:
<http://www.ncbi.nlm.nih.gov/ICTVdb/WIntkey/Images/gemini1.jpg>

Links:
Information on mungbean diseases, including yellow mosaic:
<http://www.avrdc.org/LC/mungbean/production/disease.html>
MYMV taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.029.0.03.026.htm>
MYMV, list of strains and distribution map:
<http://gemini.biosci.arizona.edu/viruses/mymv/index.html>
MYMIV, list of strains and distribution map:
<http://gemini.biosci.arizona.edu/viruses/mymiv/index.html>
MYMIV in Pakistan:
<http://www.bspp.org.uk/ndr/july2004/2004-18.asp>
Publication on adaptation of MYMIV to new hosts:
<http://pubs.nrc-cnrc.gc.ca/tcjpp/k05-041.html>
MYMIV with satellite, increase in symptom severity:
<http://www.bspp.org.uk/ndr/jan2005/2004-67.asp>
Punjab Agricultural University:
<http://www.ludhiana.nic.in/html/punjab_agri_univ.html>.  - Mod.DHA]

[see also in the archive:
2004
----
Severe leaf curl disease, cowpea - India 20041119.3098]

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