AgroPages-China’s Hebei: cucumber downy mildew has universal resistance to metalaxyl and azoxystrobin-Agricultural news

By Think Real - In order to make it clear about the dynamic resistance of cucumber downy mildew to metalaxyl and azoxystrobin and the prevention and control of cucumber downy mildew, the Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences (PPI, HAAFS) monitored the resistance of cucumber downy mildew to metalaxyl and azoxystrobin in Hebei Province during 2011-2015.

The results showed that a total of 838 cucumber downy mildew strains have universal resistance to metalaxyl and azoxystrobin and the resistance ratios reach 483.0 and 355.0 respectively; in addition, the resistance of cucumber downy mildew to metalaxyl and azoxystrobin fluctuates in different areas and different years. In particular, the resistance in Tangshan, Cangzhou, Shijiazhuang, Hengshui, Langfang and Baoding cities is higher than that in other areas, and the fluctuations are large in different years.

Table 4: Prevention and control effect of certain pesticides on cucumber downy mildew in Hebei Province

Pesticide	Prevention and control effect
250g/L Azoxystrobin SC	72.2%-74.13%
68% Metalaxyl-M + mancozeb WDG	65.3%-70.2%
58% Metalaxyl + mancozeb WP	63.3%-68.4%
50% Dimethomorph WP	>82.0%
250 g/L Mandipropamid SC
687.5 g/L Fluopicolide + propamocarb hydrochloride SC

Source: PPI, HAAFS

The prevention and control of 50% dimethomorph WP, 250 g/L mandipropamid SC and 687.5 g/L fluopicolide + propamocarb hydrochloride SC 50%, sprayed in the recommended dosages, reaches 82%+, which indicates fine prevention and control of cucumber downy mildew. In the areas where cucumber downy mildew is resistant to metalaxyl, azoxystrobin and metalaxyl-M, the above 3 pesticides can be used as substitutes or can be mixed for use.