title: Sensitivity to cymoxanil in Italian populations of Plasmopara viticola oospores.
abstract: BACKGROUND
  The level of sensibility towards cymoxanil was quantified by oospore germination assays in 28 populations of Plasmopara viticola (Berk. et Curt.) Berlese and De Toni sampled from different Italian regions from 2009 to 2012.
  
  
  RESULTS
  The populations showed good sensitivity levels, with EC50 values often lower than 10 mg AI L(-1) and percentages of resistant individuals lower than 16%. Only three populations, sampled at the end of the 2012 grapevine growing season, were characterised by high resistance levels. Field trials carried out in two of these vineyards showed that, at the beginning of the 2013 grapevine growing season, the EC50 values of P. viticola populations as measured in the sporangial assay were higher than those observed with oospores. At the end of the season, in plots where cymoxanil was not applied, the populations fully reverted to sensitivity, while the EC50 values remained high where 3-6 applications were performed.
  
  
  CONCLUSIONS
  Oospore germination assays provide valuable information on the sensitivity of populations in vineyards also at the quantitative level. The results obtained during the grapevine growing season confirm those obtained on the oospores, and that cymoxanil resistance is unstable, indirectly suggesting that the application of the fungicide according to antiresistance strategies can lead to good disease control.
authors.affiliation: Università degli Studi di Milano, DISAA, Milan, Italy.
authors.forename: Silvia L
authors.initials: SL
authors.lastname: Toffolatti
authors.affiliation: Università degli Studi di Milano, DISAA, Milan, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Venturini
authors.affiliation: Università degli Studi di Milano, DISAA, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Campia
authors.affiliation: Università degli Studi di Milano, DISAA, Milan, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cirio
authors.affiliation: SIPCAM, Agroprotezione, Pero, Milan, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Bellotto
authors.affiliation: Università degli Studi di Milano, DISAA, Milan, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Vercesi
mesh_terms: D000081:Acetamides / Q000494:pharmacology*; D000383:Agriculture; D025141:Drug Resistance, Fungal; D005659:Fungicides, Industrial / Q000494:pharmacology*; D007558:Italy; D009868:Oomycetes / Q000187:drug effects*; D027843:Vitis / Q000254:growth & development / Q000382:microbiology
chemical_list: D000081:Acetamides; D005659:Fungicides, Industrial; C025644:2-cyano-N-((ethylamino)carbonyl)-2-(methoxyimino)acetamide
keywords: EC50; downy mildew; fungicide resistance; grapevine