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Recent Rice stripe virus Epidemics in Zhejiang Province, China, and Experiments on Sowing Date, Disease--Yield Loss Relationships, and Seedling Susceptibility

August 2008 , Volume 92 , Number  8
Pages  1,190 - 1,196

H.-D. Wang, Zhejiang Provincial Station of Plant Protection and Plant Quarantine, Hangzhou, 310020, P.R. China; J.-P. Chen and H.-M. Zhang, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, P.R. China; X.-L. Sun, Jiangxing Academy of Agricultural Sciences, Jiangxing 314000, P.R. China; J.-L. Zhu, Jiangxing Station of Pest and Disease Monitoring, Jiangxing 314050, P.R. China; A.-G. Wang, Linghai Station of Plant Protection, Taizhou 317000, P.R. China; W.-X. Sheng, Huzhou Academy of Agricultural Sciences, Huzhou 313000, P.R. China; and M. J. Adams, Department of Plant Pathology and Microbiology, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK



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Accepted for publication 10 April 2008.
ABSTRACT

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% for every 1% increase in disease incidence. In inoculation experiments, young seedlings, particularly those at the three- to five-leaf stage, were the most susceptible, whereas ≤1% 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).


Additional keyword:epidemiology

© 2008 The American Phytopathological Society