Sensitivity of Mycosphaerella graminicola isolates from Tunisia to epoxiconazole and pyraclostrobin

Fifty two isolates of Mycosphaerella graminicola from Tunisia were analysed for their sensitivity to pyraclostrobin and epoxiconazole in microtitre tests and for mutations in the target genes of the modes of action, cytochrome b and CYP51, respectively. All isolates were highly sensitive to pyraclostrobin, thus no isolate carried the G143A mutation in the cytochrome b gene, the mutation which is the proved mechanism in M. graminicola for QoI resistance. The Tunisian M. graminicola population was more sensitive to epoxiconazole when compared with European populations based on previously published data. However, some mutations in the CYP51, which are known to be an adaptation response to DMIs have been found in a part of the population (e.g. mutations A379G, I381V), but there is still a portion with wild type isolates, which has already disappeared in Northern Europe. The current data indicate a favourable situation for QoI and DMI sensitivity, but it should be considered in any disease management strategy to include different modes of action to avoid QoI resistance and further adaptation to DMIs.

► All Isolates were sensitive to pyraclostrobin.
► Isolates showed different sensitivity to epoxiconazole.
► Different CYP51 haplotypes were detected.