Sensitivity Analysis of to Quinone-Outside Inhibitor and 14α-Demethylase Inhibitor Fungicides in Latvia.

Tan spot caused by is a severe threat to wheat production in all major wheat-growing regions. Sustainable tan spot control can be achieved by an integrated approach, including responsible management of fungicide sprays. The data about the sensitivity of to various fungicides in the Baltic Sea region are rare. In this study, we described the variation of sensitivity to four fungicide active ingredients to detect the formation of resistance to the most commonly used quinone-outside inhibitor (QoI) and 14α-demethylase inhibitor (DMI) fungicides in the pathogen's population in Latvia. The effect of prothioconazole, mefentrifluconazole, pyraclostrobin, and azoxystrobin on 93 strains from various hosts was tested in vitro by assessing mycelium linear growth inhibition at three different active ingredient concentrations (0 0.01, 0.1 and 0.5 mg L). Pathogen sensitivity significantly ( < 0.001) varied between the fungicide active ingredients and strains. The prothioconazole (concentration 0.5 mg L) had the most significant effect, with a median mycelial growth inhibition of 70.34%, followed by pyraclostrobin (47.02%), azoxystrobin (24.24%), and mefentrifluconazole (11.11%). Mutation G143A was detected in gene sequences and confirmed the resistance formation in Latvia's population, while F129L and G137R mutations were absent. This study provided insight into population's sensitivity to active ingredients of DMI and OoI fungicide groups, helping to fill the knowledge gap about the pathogen fungicide sensitivity in this region.