Phenotypic and molecular characterization of resistance to the SDHI fungicide fluopyram in populations of Alternaria alternata from pistachio orchards in California

In this study, the sensitivity of 902 isolates of A. alternata collected before and after the commercial use of fluopyram were assessed using mycelial growth tests. Distribution of 50% effective concentration (EC50) values for 116 A. alternata isolates (population A), collected in 2011 from an experimental orchard that had been treated with fluopyram products or boscalid showed that 86% of the isolates displayed different levels of resistance to...