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[1] Date: 20 Mar 2008
Source: Agence France-Presse [edited]
<http://afp.google.com/article/ALeqM5gkShYFELEFP-LTXbOyt7i0CNtaiA>

Viet Nam rice troubles could affect region: expert

Viet Nam's farm sector is reeling from outbreaks of pests and disease that could threaten its neighbours including China, according to one of the world's leading rice experts. Hanoi and the world scientific community have yet to find a way to prevent another crop failure following a virus attack on rice crops, said Robert Zeigler, head of the International Rice Research Institute [IRRI; Philippines].

Viet Nam is the 5th-largest rice producer and number 3 exporter in the world, and the troubles hit some of the best rice-growing areas, Zeigler said. "They got taken by surprise and had some significant yield losses that they were just not expecting. Of course we are concerned about Viet Nam. But some of these pests can migrate up into China, and who knows if they could cause some serious problems?"

He noted that, while China is not a key player in the international rice trade, the country is by far the world's largest producer and consumer of the grain. Viet Nam also lies close to Thailand, the world's top rice exporter, and rich rice-growing areas in Myanmar and Cambodia. The severe winter in China and other climatic troubles have helped lead to spiralling prices, with many nations relying on Vietnamese exports. Prices have soared to more than 700 dollars a tonne, more than 3 times the rate of 5 years ago.

Along with other disasters, the Vietnamese problems -- a viral disease called tungro and infestations of the brown planthopper insect -- have also led to global supplies being drained. Zeigler said it was still not clear why the pest and virus attacks had swept across the southern and central regions of Viet Nam. "(Farmers) did shift varieties and the way they managed them, and so we're still trying to sort out whether it was some change in the [viral] strain or it was the change in the management practices, or both," he said.

Zeigler said nations in the region and across the world needed to invest more in agricultural research, now that the vast yield gains seen since the 1960s have begun to flatten out. "Certainly the kinds of things that took (Viet Nam) by surprise are areas of work that IRRI had to cut back on because of budget cuts," he said.

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[2] Date: 28 Feb 2008
Source: Vietnam News [edited]
<http://vietnamnews.vnagency.com.vn/showarticle.php?num=01ENV280208>

Pests damage Mekong rice fields

More than 100 000 ha of rice fields in Mekong Delta provinces have been infested by the brown planthopper. According to the Mekong Delta Agriculture and Rural Development Department, the disease spread quickly this year due to weather changes, particularly unseasonable rains in the south.

The provinces of Long An, Dong Thap, Bac Lieu and An Giang have been affected the most. Pests in Bac Lieu Province early this month damaged 21 000 ha, with about 16 000 pests per square metre in the fields in Hong Dan District. Bac Lieu Province has distributed over 10 000 tonnes of pesticide to local farmers in the past days.

The brown planthopper is known as the most devastating of rice pests, as the fly-like brown insect inserts its sucking mouth into the soft tissue of plants, extracting plant sap. The result is a field that is susceptible to disease. After the outbreak in southern provinces early this year [2008], many farmers uprooted plants and sprayed fields with a mixture of different kinds of insecticides several times a week. "This isn't proper and too much insecticide will harm rice fields for the next crop and kill other insects that are actually good for the fields," Nguyen Huu An, director of An Giang Province's Vegetation Protection Office, said. The Mekong Delta's Vegetation Protection Department predicted that new pest offsprings will emerge on rice fields, bringing viruses that cause ragged stunt rice disease.

Prof. Vo Tong Xuan, director of An Giang University, said farmers would be provided with pest-resistant rice strains for cultivation.
"They also need to be armed with knowledge on modern farming technology and the proper use of chemicals to protect their plants," he said.

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[Several epidemics of planthoppers and leafhoppers infesting rice crops and spreading virus diseases have been reported from this area in recent years. The Asian brown planthopper (_Nilaparvata lugens_) is reported to have reached very high numbers. It is one of the worst pests of rice in the Australasian and Pacific Island region and is also the vector of _Rice ragged stunt virus_ (RRSV) mentioned above, as well as _Rice grassy stunt virus_ (RGSV). A number of other rice viruses are spread by the green rice leafhopper (_Nephotettix
virescens_) including _Rice tungro bacilliform virus_ and _Rice tungro spherical virus_ (which together cause tungro disease), and _Rice yellow stunt virus_. Crop losses of up to 100 percent due to some virus diseases, for example tungro, have been reported.

Infectious vector insects transported on air currents or by people movements can spread the viruses over long distances. Disease management includes vector control, cultural practices to minimise inoculum, and the use of rice varieties resistant to the vector, the virus, or both. Cultivars resistant to the vectors have usually low virus disease incidence.

At least 15 viruses are known to affect rice, and many of these occur in Asia. A number of them are spread by different species of plant- or leafhoppers. Virus disease problems seem to have been accentuated worldwide by the introduction of modern agricultural techniques, double cropping and high yielding rice cultivars. The pathogens may have been present, but rarely reached epidemic proportions under traditional cropping systems when average rice yield was low.
Intensified cultivation and increased use of agrochemicals have also enhanced the possibilities for the emergence of more virulent strains of both viruses and vectors.

Maps
Viet Nam:
<http://www.lib.utexas.edu/maps/middle_east_and_asia/vietnam_pol01.jpg>  and <http://healthmap.org/promed?v=14.9,108.5,5>
Viet Nam provinces:
<http://www.angelfire.com/co/hongnam/vnmap.html>
South-East Asia:
<http://mabryonline.org/blogs/howard/archives/map_southeast_asia.jpg>
Distribution of several rice viruses in southern Viet Nam:
<http://www.kper.or.kr/img/board/75ho_info_05.jpg>

Pictures
Rice virus symptoms:
-- RRSV
<http://www.ricethailand.go.th/rkb/data_005/Image_Disease/rice_ragged%20stunt-05-012_B.jpg>

-- RGSV
<http://seedcenter17.doae.go.th/farmer/pest/Image_Disease/rice_grassy%20stunt-05-014_B.jpg>

-- tungro disease
<http://www.last.gov.cn/OA/upload/other/200742010053532.bmp>
Brown planthoppers:
<http://www.dpvweb.net/dpv/showfig.php?dpvno=320&figno=03>
Green rice leafhopper:
<http://www.sut.ac.th/e-texts/Agri/insectfinal2/Insects%20web/Images/chapter2_6_clip_image002.jpg>

Links
Additional link for item [1]:
<http://www.abs-cbnnews.com/storyPage.aspx?storyId=112657>
News story 'Expert warns of unrest as rice price soars':
<http://afp.google.com/article/ALeqM5iuyGtykdpffYoIeOuXPiV_d25WKg>
Review of rice viruses, biology and epidemiology:
<http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.phyto.34.1.249?journalCode=phyto>

Illustrated fact sheets for all major diseases and pests of rice via:
<http://www.knowledgebank.irri.org/RiceDoctor/default.htm>
List of rice diseases and pathogens:
<http://www.apsnet.org/online/common/names/rice.asp>
Taxonomy and descriptions of rice viruses via:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/index.htm>
_N. lugens_ taxonomy and distribution map:
<http://www.environment.gov.au/cgi-bin/abrs/fauna/details.pl?pstrVol=FULGOROIDEA;pstrTaxa=1909;pstrChecklistMode=2>

_N. virescens_ taxonomy:
<http://www.ento.csiro.au/aicn/system/c_1482.htm>
IRRI:
<http://www.irri.org>
- Mod.DHA]