Fungicide sensitivity of Clarireedia spp. isolates from golf courses in China

Abstract

Abstract Dollar spot, caused by Clarireedia spp. (formerly Sclerotinia homoeocarpa), is a devastating turfgrass disease worldwide. Strong selection pressure imposed by continuous fungicide applications has caused the emergence of fungicide resistance in fungal populations. In this context, a total of 358 isolates of Clarireedia spp., collected from 25 locations in the north, east and south regions of China, were assayed for in vitro sensitivities to thiophanate-methyl, iprodione, propiconazole, and boscalid using discriminatory concentrations of 10\xa0μg/mL, 1\xa0μg/mL, 0.1\xa0μg/mL and 10\xa0μg/mL, respectively. Relative mycelial growth (RMG) was used to determine sensitivity or resistance based on comparison with baseline populations. A total of 18, 11 and 14 of the 25 locations exhibited significantly reduced sensitivity (P