A ProMED-mail post
<http://www.promedmail.org>
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International Society for Infectious Diseases <http://www.isid.org>
Date: Tue 28 Apr 2009
Source: The News Today (TNT, Philippines) [edited] <http://www.thenewstoday.info/2009/04/28/rats.tungro.virus.affect.405.has.rice.land.in.aklan.html>
Rats and tungro virus have affected 405 hectares [1000 acres] of
rice land in the province of Aklan. The agriculture department
and the town officials have already put in place measures to
contain the pest infestation and crop disease. The report on
Aklan's pest infestation and crop disease was furnished by
Department of Agriculture's [DA] Larry Nacionales to DA
secretary Arthur Yap. However, the press report provided to TNT
did not identify the affected rice growing municipalities in the
province.
The DA will provide training to help the farmers adopt better
pest management practices which are deemed effective against the
spread of pests and crop diseases. The farmers are urged to seek
the help of municipal agriculture officers. Yap believes the
massive information campaign, farmers' field schools, and palay
[unmilled rice] check program could effectively minimize the
effects of the infestation.
The DA will [also] train the farmers on how to program their
planting and harvest schedule. Better seed varieties will be
distributed in the next planting season to control the
infestation.
[Byline: Maricar M Calubiran]
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Communicated by:
ProMED-mail
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[Tungro is one of the most damaging rice diseases in South East
Asia.
Yield losses of up to 100 percent have been reported, and the
disease is spreading in the region. It is a co-infection
involving _Rice tungro bacilliform virus_ (RTBV; genus
_Tungrovirus_, family _Caulimoviridae_) and _Rice tungro
spherical virus_ (RTSV; genus _Waikavirus_, family
_Sequiviridae_). More than one genotype of each virus may exist
in the same plant.
Symptoms include leaf discolouration, stunting, reduced
tillering, and reduced grain production. All growth stages of
rice are susceptible. Tungro is transmitted by leafhoppers, the
most efficient vector being the green leafhopper _Nephotettix
virescens_. RTBV cannot be transmitted unless RTSV is present.
Infectious vector insects can spread the viruses over long
distances. The disease is not seed transmitted.
Disease management includes vector control, crop rotation and
other cultural practices, as well as the use of rice varieties
resistant to the vectors, the viruses, or both. Vector
adaptation on leafhopper resistant varieties has been a problem,
and virus resistant varieties are at present considered the most
economical way of tungro control.
However, the presence of multiple viral genotypes in a single
location suggests an unstable virus population which poses a
challenge to achieving durable crop resistance.
Maps
Philippines:
<http://www.ac.wwu.edu/~fasawwu/resources/img/map-philippines.png>
and <http://healthmap.org/r/00aV>
Philippine provinces:
<http://www.reliefweb.int/mapc/asi_se/cnt/phil/phl_ad.html>
Pictures
Tungro symptoms on rice plant:
<http://www.last.gov.cn/OA/upload/other/200742010053532.bmp>
and <http://www.irri.org/media/achievements/images/Tungro.jpg>
Tungro-affected rice field:
<http://www.knowledgebank.irri.org/RiceDoctor/image26.jpg>
Green rice leafhopper:
<http://www.knowledgebank.irri.org/RiceDoctor/image74.jpg>
and <http://ait.nisit.kps.ku.ac.th/dbfieldcrop/picture/pkvov.jpg>
Links
Information on tungro disease:
<http://www.knowledgebank.irri.org/RiceDoctor/Fact_Sheets/Diseases/Tungro.htm>
<http://www.ias.ac.in/currsci/oct252003/1143.pdf>
Information on tungro viruses and management:
<http://www.irri.org/science/abstracts/009.asp>
and <http://ricehopper.files.wordpress.com/2008/12/component-technologies.pdf>
_Rice tungro spherical virus_ taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.065.0.02.004.htm>
_Rice tungro bacilliform virus_ taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.015.0.04.001.htm>
Green leafhopper information:
<http://www.knowledgebank.irri.org/RiceDoctor/Fact_Sheets/Pests/Green_Leafhopper.htm>
_N. virescens_ taxonomy:
<http://www.ento.csiro.au/aicn/system/c_1482.htm>
International Rice Research Institute (IRRI):
<http://www.irri.org>. -
Mod.DHA]
[see also
in the
archive:
2008
----
Tungro disease, rice - Philippines: (SCO) 20080902.2744 Virus
diseases, rice - Viet Nam: update (02) 20080322.1093 Virus
diseases, rice - Viet Nam: update 20080118.0221
2007
----
Virus disease, rice - Viet Nam (02) 20070614.1939 Virus disease,
rice - Viet Nam 20070611.1899]