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: 23 Jul 2009
Source: Business World [edited]
<http://www.bworldonline.com/BW072309/content.php?id=124>
The tungro virus has been found in ricefields in Ajuy, Barotac
Viejo, Concepcion, Dingle, Pototan, San Enrique, Sara and Sta.
Barbara towns in Iloilo; Cuartero, Dao, Jamindan and Mambusao in
Capiz; and Malinao in Aklan.
Pests being monitored by the Department of Agriculture regional
office include the rice tungro virus and the rice black bug,
which could also emerge at this time. As of last week, about 25
hectares of rice plantations had been affected in Iloilo. Some
17 hectares in Capiz are also infested.
Continuous rains have created an environment conducive to the
proliferation of pests, said DA Regional Executive Director
Larry Nacionales, who formed the Rice Crop Protection Task Force
to monitor pests and diseases affecting the region's rice
production during the critical planting months of June and July
[in 2009].
--
Communicated by:
ProMED-mail Rapporteur Susan Baekeland
[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, cultural practices,
and use of rice varieties resistant to the vectors and/or the
viruses.
However, vector adaptation on leafhopper resistant varieties has
been a problem, and the presence of multiple viral genotypes in
a single location (suggesting an unstable virus population)
poses a challenge to achieving durable crop resistance. Research
on tungro management is being carried out at the International
Rice Research Institute
(IRRI) in the Philippines.
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>
and
<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>
Tungro management in the Philippines:
<http://www.irri.org/science/abstracts/009.asp>.
- Mod.DHA]
[see also
in the
archive:
Tungro disease, rice - Philippines: (AK) 20090430.1634
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] |
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