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Date: August 2008
Source: The American Phytopathological Society, Plant Disease 2008; 92(8): 1190-6 [edited]
<http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-92-8-1190>

[Ref: HD Wang et al: Recent _Rice stripe virus_ epidemics in Zhejiang Province, China, and experiments on sowing date, disease-yield loss relationships, and seedling susceptibility. Plant Dis 2008; 92(8):
1190-6; DOI: 10.1094/PDIS-92-8-1190]

_Rice stripe virus_, transmitted by the small brown planthopper _Laodelphax striatellus_, has recently reemerged as a major disease in Zhejiang province, eastern China. Intensive surveys during 2003 to
2006 demonstrated how the disease has spread rapidly from the northern to central and eastern regions with increasing incidence each year.

In bioassays, the highest proportions of viruliferous vectors were from regions where the disease was most severe. The greatest disease incidence was in the earliest sown plants, and substantial control could be achieved by delaying planting from late May to mid-June. In experiments where different proportions of infected plants were established (by inoculation or varying the sowing date), average yield losses were 0.8 percent for every one percent increase in disease incidence. In inoculation experiments, young seedlings, particularly those at the 3- to 5-leaf stage, were the most susceptible, whereas up to one percent of plants inoculated at or after the elongation stage developed symptoms.

Recent epidemics appear to have resulted from large populations of viruliferous vectors colonizing rice seedlings at the most susceptible stage. This is probably because of changes in cropping practice, recent warmer winters in Zhejiang province, and the development of resistance or tolerance to the insecticides widely used (triazophos, synthetic pyrethroids, and imidacloprid).

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[Rice stripe disease caused by _Rice stripe virus_ (RSV) leads to severe or even crippling losses in many rice-growing regions. RSV is the type member of the genus _Tenuivirus_, which has not yet been assigned to a family, and is serologically related to _Maize stripe virus_ and _Rice grassy stunt virus_. The virus spreads in East Asia and has been recorded in China, Japan, Taiwan, Korea, and parts of Russia. It also affects other grassy hosts including wheat, barley, oats, maize, millets, and some weeds, but only rice and wheat are reported to serve as virus reservoirs. Symptoms on rice include chlorotic stripes or mottling on leaves, necrotic streaks, and wilting. Rice plants infected at the early growth stages are worst affected, showing severe symptoms and premature death.

RSV is transmitted in a persistent manner by several planthopper species. It is propagative in the vectors and transmitted to the progeny via the eggs. The most important vector is the small brown planthopper, _L. striatellus_, which is often responsible for epidemics of the disease. The effects of RSV on _L. striatellus_ are uncertain but RSV may shorten the insects' life span. RSV detection in this vector is being used for disease forecasting. RSV can also be mechanically transmitted at low efficiency. Disease management includes cultural techniques (for example planting time, reduction of inoculum), vector control, and use of resistant cultivars.

Maps
China:
<http://www.chinapage.com/map/map.html>  and <http://healthmap.org/promed?v=36.5,103.9,4>
Zhejiang province:
<http://www.maps-of-china.com/zhejiang-s-ow.shtml>

Pictures
RSV symptoms:
<http://www.pref.aichi.jp/byogaichu/seitaitoboujyo/0-ine/simahakare-higai1.jpg>
RSV particles:
<http://www.ncbi.nlm.nih.gov/ICTVdb/WIntkey/Images/em_tenui.gif>
_L. striatellus_:
<http://www.last.gov.cn/oa/upload/other/2007919114515838.bmp>

Links:
Information on RSV and diagnosis (abstract; subscription required for full text): LINK
Description of RSV:
<http://image.fs.uidaho.edu/vide/descr693.htm>
Information on RSV and other rice viruses (abstract; subscription required for full text):
<http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.phyto.34.1.249?journalCode=phyto>
RSV taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.069.0.01.001.htm>
Information on _L. striatellus_:
<http://popgen.unimaas.nl/~jlindsey/commanster/Insects/Bugs/SuBugs/Laodelphax.striatellus.html>
and
<http://www.cabicompendium.org/NamesLists/CPC/Full/CALGMA.htm>
_L. striatellus_ taxonomy:
<http://www.uniprot.org/taxonomy/195883>.  - Mod.DHA]