Investigation on Mosaic Virus Diseases of Flue-cured Tobacco after Top-ping in Yunnan Province in 2020
In recent years,the occurrence of viral diseases with mosaic-liked symptom on flue-cured tobacco leaves in some tobacco growing areas of Yunnan has new features:the incidence is always slow during growing stage before topping.However,a rapid and contiguous increase in incidence is observed after topping.In order to detect the pathogens of these diseases and illustrate their characteristics and distribution,617 tobacco leaf samples with typical symptoms,such as mosaic,vein banding,etch and leaf vein necrosis(abbreviation as:mosaic-liked disease)were collected from 17 tobacco planting counties or districts in 8 cities or prefectures from June to August in 2020 and tested by using Tobacco mosaic virus(TMV),Potato virus Y,(PVY),Chilli veinal mottle virus(Chi-VMV)and Tobacco vein banding mosaic virus,(TVBMV)ELISA kit,respectively.The detection rates,with a des-cending order,were 52.51％for TVBMV,50.08％for TMV,41.49％for CHIVMV and 14.31％for PVY,respec-tively.Summarily,the distribution of virus diseases with leaf mosaic symptom after topping in 2020 showed the following trends:aphid borne Potyvirus,such as PVY,CHIVMV and TVBMV were dominant,while the propor-tion of the long-term damaging TMV has decreased.The proportions of the three major viruses from potyvirus were variable in different geographic areas.TVBMV and PVY were dominant in Northeast Yunnan(Zhaotong and Northern Qujing),which are traditional potato growing areas.PVY resistant varieties(Yunyan 301,Yunyan 121)have shown economic and effective disease control effect in these areas.CHiVMV and TVBMV were the main pathogens in Central Yunnan(Kunming and Yuxi).CHiVMV is dominant in West Yunnan(Dali and Baoshan).More attentions should be paid to that the rapid infection of TVBMV and CHiVMV after topping in most sampling sites.More filed survey and virus detection of mosaic-liked disease in tobacco planting region need to be carried out to formulate disease-resistant varieties layout and targeted control measures.
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