A ProMED-mail post
<http://www.promedmail.org>
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International Society for Infectious Diseases <http://www.isid.org>
Date: Mon 2 Nov 2009
Source: The News Today [edited]
<http://www.thenewstoday.info/2009/11/02/
p8.5m.lost.to.rice.tungro.infestation.in.antique.html>
Rice tungro infestation has damaged rice farms in 11 municipalities in the province of Antique. The Office of the Provincial Agriculturist (OPA) placed the total worth of damage at PHP 8.5 million [about USD 180 000].
The IPM [Integrated Pest Management] coordinator said the virus was last seen in this scale during 1982.
It is one of the most harmful diseases for rice plants. It is spread by the green and zigzag leafhoppers, common pests in rice paddies. The OPA issued several recommendations for managing the disease, such as discouraging 3 croppings a year for communities with confirmed infection, synchronous planting for whole communities, plowing infected seedbeds, and eliminating weeds that serve as hosts for the rice tungro virus.
Based on the inventory of all government stocks, secretary Arthur Yap of the Department of Agriculture (DA) assured Filipinos that rice supply is stable. He said that apart from the stocks held in 500 warehouses all over the country, ongoing harvests in the Visayas and Mindanao will boost the inventory. The government also has started importing rice and initial shipments will arrive by January 2010. "All in all, we are looking at about 140 days' worth of stocks," he stressed, as he sought to allay fears.
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[Tungro is one of the most damaging rice diseases in South East Asia. Yield losses of up to 100 per cent 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, but losses are higher for infections early in the growth cycle. Tungro is transmitted by leafhoppers including the zigzag leafhopper (_Recilia
dorsalis_) mentioned above, but the most efficient vector is 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.
Serious outbreaks of tungro have been reported earlier in 2009 from the provinces of Iloilo, Capiz, and Aklan, which border Antique in the Visayas region of the central 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://ricehopper.files.wordpress.com/2008/12/tungro-in-field2.gif>
Green rice leafhopper:
<http://ait.nisit.kps.ku.ac.th/dbfieldcrop/picture/pkvov.jpg>
Zigzag leafhopper:
<http://www.malaeng.com/blog/wp-content/pictures/2007/09/recilia-dorsalis.jpg>
Links
Information on tungro disease:
<http://www.knowledgebank.irri.org/riceDoctor/index.php?option=com_content&view=article&id=568&Itemid=2773>
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://ricehoppers.net/2008/12/17/
component-technologies-for-rice-tungro-disease-management/>
_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/index.php?option=com_content&view=article&id=614&Itemid=2804>
_N. virescens_ taxonomy:
<http://www.ento.csiro.au/aicn/system/c_1482.htm>
Zigzag leafhopper information:
<http://www.knowledgebank.irri.org/riceDoctor/index.php?option=com_content&view=article&id=593&Itemid=2825>.
- Mod.DHA]
[see also:
Tungro disease, rice - Philippines (02) 20090726.2639 Tungro disease, rice - Philippines: (AK) 20090430.1634
2008
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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
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Virus disease, rice - Viet Nam (02) 20070614.1939 Virus disease, rice - Viet Nam 20070611.1899]
