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A Study on the Overwintering of Cucumber Downy Mildew Oospores in China

Author:
Zhang, Yan‐ju, Pu, Zi‐jing, Qin, Zhi‐wei, Zhou, Xiu‐yan, Liu, Dong, Dai, Li‐ting, Wang, Wen‐bo
Source:
Phytopathologische Zeitschrift 2012 v.160 no.9 pp. 469-474
ISSN:
0931-1785
Subject:
Pseudoperonospora cubensis, cucumbers, disease occurrence, downy mildew, greenhouses, oospores, overwintering, viability, China
Abstract:
Oospore formation of Pseudoperonospora cubensis was investigated in 10 Chinese locations: Mohe, Harbin, Changchun, Shenyang, Beijing, Liaocheng, Yinchuan, Xining, Yangling and Haikou. Oospores were observed in all but Haikou. Oospore viability was monitored from 10 January to 10 July 2009, in Harbin. Percentages of activated oospores increased from 10 April with a peak in late May (14.0% on 25 May 2009), and then decreased. This is in accordance with the usual time of downy mildew appearance in Harbin, 20–30 May. Inoculation tests using the oospores overwintered in Harbin, whether in the greenhouse or outdoors, showed that these were viable, with a disease occurrence of 26.6–95.0%. Oospores overwintering locally could be primary infection sources of downy mildew in cool temperate northern China.
Agid:
404380