Analisi temporale della resistenza all'ammide dell'acido carbossilico (CAA) mandipropamid in popolazioni di Plasmopara viticola

TIME SERIES INVESTIGATION OF RESISTANCE TO THE CARBOXYLIC ACID AMIDE (CAA) MANDIPROAMID IN PLASMOPARA VITICOLA POPULATIONS The fungicide resistance dynamics in field populations of fungal pathogens are influenced by the complex interactions of several factors, such as pathogen, host, fungicide and environment. In this study mandipropamid, a member of the medium-risk fungicide class Carboxylic Acid Amides (CAA), was employed in an antiresistance strategy against a high risk pathogen, Plasmopara viticola, to evaluate the efficacy in disease management in relation to fungicide sensitivity in real field conditions. The CAA sensitivity and the G1105S/V mutations were analyzed at four phenological stages over a 4-year period in two commercial vineyards with pathogen populations charachterized by different starting levels of resistance: resistance and sensitivity to CAA. The results from both fields showed a good disease control, comparable to that achieved by applying other fungicide classes, despite the different G1105S/V frequencies and sensitivity patterns. The two starting populations changed over time depending on the strategy applied and return to sensitivity was favoured by the absence of mandipropamid treatments for three consecutive years.