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Subject: [redesastres-l] RV: PRO/PL> Rice hoja blanca virus - Ecuador: (GY, LR)
Date: Wed, 23 Dec 2015 10:04:25 -0800
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Asunto: PRO/PL> Rice hoja blanca virus - Ecuador: (GY, LR)
RICE HOJA BLANCA VIRUS - ECUADOR: (GUAYAS, LOS RIOS)
****************************************************
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: Thu 10 Dec 2015
Source: Ecuador Times [edited]
<http://www.ecuadortimes.net/2015/12/10/rice-producers-threatened-by-the-sog
ata-disease/>
Rice crops are threatened by an attack of "sogata" disease, a virus that
reduces production up to 50 per cent. Heitel Lozano, National Corporation of
Rice Farmers (Corpoarroz), raised the alarm: plants are affected in the
provinces of Guayas and Los Rios.
During the rainy season, growers use varieties that are the most susceptible
to the attack of this disease. "There are some (varieties) which are
resistant, but Iniap 14 and 15, which are the most widely sown, are
moderately resistant; with these weather problems, they begin to be very
susceptible," said Lozano.
This is a major problem, because the [yield] reduction will affect the
economy, since rice is the most consumed product in the country.
[byline: Mercedes Cabrera]
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[Rice hoja blanca virus (RHB; genus _Tenuivirus_) has only been reported
from the Americas, where it causes a serious disease of the crop. Symptoms
may include chlorosis and bleaching of leaves, leaf necrosis, stunting, loss
of plant vigour and reduced seed production.
Yield losses are largest when plants are infected early in the cropping
cycle.
RHBV is transmitted specifically by the plant hopper vector _Tagosodes_
(previously _Sogatodes_) _orizicolus_, which can also cause severe damage
("hopper burn") to the plants in its own right.
Other than to rice, it can also transmit RHBV to other graminaceous hosts,
including oats, barley, rye and some grasses. The vector cannot overwinter
in cool regions, and this limits the range of RHBV. High vector numbers, for
example due to moist conditions in the case above, may lead to a high
incidence of virus. However, some pathogenic effect of RHBV on the vector
insects has been observed, which may explain a cyclical nature of disease
outbreaks.
Disease management of insect-transmitted viruses mostly depends on vector
control with insecticides as well as removal of virus and vector reservoir
hosts near crops. Rice varieties with various levels of resistance to RHBV
or its vector are available, and most Japonica rice varieties are resistant
to RHBV.
Other rice viruses in the same genus (such as _Rice stripe virus_ and _Rice
grassy stunt virus_) originate in Asia and are transmitted by different
plant hopper vectors.
Maps
Ecuador:
<http://i.infoplease.com/images/mecuador.gif>
Ecuador provinces:
<http://www.mapsofworld.com/ecuador/ecuador-political-map.html>
South America, overview:
<http://www.worldatlas.com/webimage/countrys/samerica/printpage/samainp.htm>
Pictures
RHBV symptoms:
<http://www.cenicana.org/pictures/investigacion/hoja_blanca.jpg>
Vector, adult insects:
<http://iasvn.org/Images_upload/images/New%20Picture%20%2828%29%287%29.png>
RHBV particles, electron micrographs:
<http://www.dpvweb.net/dpvfigs/d299f03.jpg> and
<http://www.dpvweb.net/dpvfigs/d299f04.jpg>
Links
Information on RHBV:
<http://ciat-library.ciat.cgiar.org/Articulos_Ciat/2010-Morales_Rice_hoja_bl
anca.pdf>,
<http://www.dpvweb.net/dpv/showdpv.php?dpvno=299> and
<http://pvo.bio-mirror.cn/descr689.htm>
Resistance to virus and vector:
<http://iasvn.org/en/homepage/Major-QTLs-Control-Resistance-to-Rice-Hoja-Bla
nca-Virus-and-Its-Vector-Tagosodes-orizicolus-2100.html>
and
<http://www.ots.ac.cr/rbt/attachments/volumes/vol60-1/07_Gonzalez_Oryza_sati
va.pdf>
Virus taxonomy via:
<http://ictvonline.org/virusTaxonomy.asp?version=2014>
Information on vector _T.orizicolus_:
<http://naturalhistory.museumwales.ac.uk/vectors/browsespecies.php?-recid=70
0,
<http://www2.agro.unlp.edu.ar/uploads/R/104_151_156.pdf> (in Spanish) and
via <http://ag.udel.edu/research/delphacid/species/tagosodes.htm>
 - Mod.DHA
A HealthMap/ProMED-mail map can be accessed at:
<http://healthmap.org/promed/p/8>.]
[See Also:
2008
---
Virus diseases, rice - Viet Nam: update
http://promedmail.org/post/20080118.0221
2007
---
Virus disease, rice - Viet Nam
http://promedmail.org/post/20070611.1899
1997
---
Rice hoja blanca & rice stripe viruses: RFA
http://promedmail.org/post/19971015.2132
1996
---
Rice virus - Latin America http://promedmail.org/post/19960430.0833]
October 21, 2020. Centro Nacional de Sanidad Agropecuaria, webmaster@censa.edu.cu .