First report of resistance to carbendazim and procymidone in Botrytis cinerea from strawberry, blueberry and tomato in Argentina

Botrytis cinerea is a necrotrophic plant pathogen that causes gray mold: a disease inflicting significant damage and crop losses in a wide range of cultivated plant species in Argentina and elsewhere. In Argentina, control of gray mold with the two mainstay fungicides, Carbendazim (Car) and Procymidone (Prc), has become ineffective, suggesting that this pathogen has developed resistance to these fungicides active ingredients. However, the actual sensitivity of this pathogen to these fungicides and the genetic basis for resistance in the region are unknown. In this study, we report the sensitivity to Car and Pre of 12 isolates of B. cinerea collected in Argentina. The fungus was recovered from diseased strawberry and blueberry fruits and tomato leaves from four commercial locations in 2017. Seven isolates were resistant to Car (Car-R), two to Prc (Prc-R), and two had both Car and Prc resistance (CarPrc-R). All the Car-R phenotypes carried the point mutation E198A in the beta-tubulin gene (tub) and all the Prc-R phenotypes carried the point mutations Q369P and N373S in the two-component histidine kinase gene (Bos1). To our knowledge, this is the first report of resistance to Car and Prc in B. cinerea from strawberry, blueberry and tomato in Argentina. A comprehensive survey to document the regional occurrence of resistance in the country is underway.