Distribution of Baseline Sensitivities to Dimethomorph Among Isolates of Pseudoperonospora cubensis and Resistance Monitoring in the Field in China

摘要：

　　The susceptibility of Pseudoperonospora cubensis (causal agent of cucumber downy mildew) to cucumber was conducted using leaf discs on the effect of cucumber leaf ages, effect of different inoculums, and effect of surfac tants (methanol, Tween 20, and the mixture of them).Results showed that the leaves from position 4 to 6 in a plant was more susceptive, greener and fresher for disease incidence evaluation; 1 × 104 sporangia/ml inoculum of P.cubensis was more expediency with consistency of results and easy to get the mounts of sporangia; 0.005% Tween 20 with or without 0.02% methanol had no effect on the disease incidence.Thus, they were chosen for next baseline sensitivity and resistance monitoring studies.In 2007 growing seasons, 90 single-lesion isolates of P.cubensis col lected from Liaoning and Jiangsu provinces, which had never treated with CAA fungicides, were used to test basen line sensitivities to dimethomorph.Result exhibited the baseline sensitivities was distributed as unimodal curve, with individual EC50 values ranged from 0.0176mg/L to 0.5572 mg/L (mean 0.1879 (± 0.1251) mg/L).Based on this data, a total of 535 single-lesion isolates of P.cubensis were obtained from infected cucumbers in plastic green houses or fields in 2007 and 2008 in Shanxi, Shandong, Anhui, Jiangsu, Henan, Hainan and Hulei provinces in China, where CAA fungicides had been extensively applied ; and detedted for the sensitivities to dimethomorph at dis criminatory concentrations of0, 4, 8 and 16 mg L.Results showed that all the isolates presented highly sensitivity or low-resistance to the fungicide, and no resistant isolates were detected.Therefore, dimethomorph could be remain as the major fungicide for controlling cucurbit downy mildew in China.

关键词： baseline sensitivity CAA fungicides cucumber downy mildew fungicide resistance

作者: Hancheng Wang Wenhong Li Haiyan Sun Gerd Stammler Jianxia Ma Mingguo Zhou

作者单位: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R.China BASF SE, 67117 Limburgerhof, Germany BASF (China) Co.Ltd., Shanghai 200001, P.R.China

会议类型: 国内会议

会议名称: 中国植物病理学会化学防治专业委员会第七届中国植物病害化学防治学术研讨会

会议地点: 海口

会议语种:英文

页码: 137-149

在线出版日期: 2010-11-20（万方平台首次上网日期，不代表论文的发表时间）