Monitoraggio della resistenza ai principali fungicidi antiperonosporici in Lombardia

The protection strategies applied to control the epidemics of grapevine downy mildew agent Plasmopara viticola aim at avoiding the selection of strains resistant to the monosite fungicide inside the pathogen population. Monitoring the resistance levels intends, on the one hand, to establish the baseline sensitivity of the population and, on the other, to evaluate the effectiveness of anti-resistance strategies. In the present study, P. viticola populations isolated from 26 vineyards located in Lombardy (Northern Italy) were tested for their sensitivity to different fungicides/fungicide classes: azoxystrobin (QoI), mandipropamid (CAA), metalaxyl (PA), cymoxanil, cyazofamid, fluopicolide and zoxamide. Resistance was evaluated by the oospore germinability at discriminating doses (azoxystrobin and mandipropamid) or by the EC50 calculation. In general, the populations were characterized by good sensitivity levels toward the different active ingredients, with some exceptions related to the intensive use of the fungicide.