Detection Of Five Major Fungicides Resistant Of Plasmopara Viticola From Main Grapevine Areas In China

Grape downy mildew is one of the most serious diseases on grapevine in China and the world.Chemical control is still the most common and effective method to control this disease.There were five major categories of systemic fungicides that commonly applied on grapevine,including Phenylamides(PAFs),Strobilurins(QoI),Carboxylic Acid Amides(CAAs),Cyano-Acetamide and Sulfamimidazoles.However,application of chemical fungicides had led to an increased risk of fungicide resistance and the emergence of fungicides resistance has caused a decline in the efficacy of fungicides,which has brought huge losses in commercial vineyards.In order to clarify the current status of resistance to five major fungicides and the development trend of fungicides resistance in main grapevine areas in China,this research used traditional leaf disk floating method to detect the resistance of Plasmopara viticola to cymoxanil,cyazofamid and metalaxyl.The resistance of P.viticola to azoxystrobin and dimethomorph was detected by Taqman-MGB molecular detection technology.The resistance frequency and resistance level of P.viticola to the five major fungicides in each grapevine area were monitored,which provided theoretical guidance for the scientific and rational use of fungicides and the effective prevention and control of grape downy mildew.The main findings are as follows: 1.Established a sensitive baseline and monitored the resistance of P.viticola to cymoxanil and cyazofamid in the main grapevine regions of China.The sensitive baseline of P.viticola to cymoxanil was 8.488 ± 7.198 μg/mL,the sensitive baseline of P.viticola to cyazofamid was 0.440 ± 0.576 μg/mL.The results of resistance type analysis showed that the sensitivity of P.viticola to cymoxanil and cyazofamid was not serious,only certain proportion of low and medium-resistant isolates appeared in some grapevine areas in China.Among them,the resistance level of P.viticola to cymoxanil in Langfang City of Hebei Province,Jurong City of Jiangsu Province,Xingan and Ziyuan County of Guangxi Zhuang Autonomous Region,Binchuan County of Yunnan Province were higher,and the resistance level of P.viticola to cyazofamid in Gongan County of Hubei Province,Zhijiang County of Hunan Province,Haerbin City of Heilongjiang Province,Yantai and Jinan City of Shandong Province were higher.The others were both lower.Cross-resistance analysis showed that there was no cross-resistance relationship between cymoxanil and cyazofamid.2.Detected the resistance of P.viticola to metalaxyl in main grapevine regions of ChinaThe resistance frequency and resistance level of P.viticola to the metalaxyl in the main grapevine areas were higher.Among them,the resistance frequency and level of P.viticola in Xing’an County of Guangxi Zhuang Autonomous Region,Gongan County of Hubei Province,Jurong City of Jiangsu Province and Yantai City of Shandong Province were both higher,the resistance frequency of P.viticola in Zhijiang County of Hunan Province,Gongzhuling city of Jilin Province were higher,but the resistance level was lower,and the resistance frequency and resistance level of P.viticola in Qingxu County of Shanxi Province and Harbin City of Heilongjiang Province were both lower.Moreover,the decline of resistance frequency and resistance level was found in Binchuan County of Yunnan Province and Zhijiang County of Hunan Province by monitoring of two years.3.Detected the resistance of P.viticola to the azoxystrobin and dimethomorph in the main grapevine areas of ChinaThe resistance frequency of P.viticola to azoxystrobin was higher and the trend of resistance frequency were varies in different regions of China.The frequency of resistance to azoxystrobin in Ziyuan and Xingan County of Guangxi Zhuang Autonomous Region,Binchuan County of Yunnan Province,Sandu County of Guizhou Province,Zhijiang County of Hunan Province,Gongan County of Hubei Province,Penglai City,Yantai City and Jinan City of Shandong Province,Shijiazhuang and Langfang City of Hebei Province,Huanren County and Beizhen City of Liaoning Province were higher,and other areas were lower.The results of the resistance to dimethomorph showed that the resistance frequency of P.viticola to dienomorpholine was low,and the frequency of resistance allele was higher in some regions.The resistance frequency and resistance allele frequency of the pathogens in Jinan City of Shandong Province,Huanren County of Liaoning Province,Zhijiang County of Hunan Province,Langfang and Shijiazhuang City of Hebei Province were both higher.Gongan County of Hubei Public,Yantai and Penglai City of Shandong Province,Zhangjiakou City of Hebei Province,Beizhen City of Liaoning Province and Harbin of Heilongjiang Province had low frequency of resistance but high frequency of resistance alleles.The resultes showed that the potential risk of fungicide resistance were higher.The resistance frequency and allele frequencies were both lower in other regions.The trend of resistance and allel frequency were varies in different regions of China.