Resistance to fungicides in French populations of Septoria tritici, the causal agent of wheat leaf blotch.

摘要

In field strains of Septoria tritici [Mycosphaerella graminicola], resistance to benzimidazoles, strobilurins and inhibitors of sterol 14 alpha -demethylation (DMIs) is determined by mutations in genes encoding their respective target sites. For benzimidazoles and strobilurins, resistance levels are high and result in a reduced field performance of these fungicides. Regarding DMIs, several mutations have been identified and determine low to medium resistance levels; moreover, cross resistance between DMIs is not always observed. The practical efficacy of DMIs, especially triazoles, remains good. Under field conditions, the highest selection pressures towards strains highly resistant to QoIs and moderately resistant to DMIs are recorded when strobilurins and triazoles, respectively, are applied at high doses. The combinations of members of group with reduced doses have a generally a less pronounced effect. Prochloraz was the only DMI that did not select strains moderately resistant to this class of fungicides..