EUROPE – COM: New draft regulation for the addition of unacceptable co-formulants
29 January 2026
This memo has been written by experts from INRAE, ANSES and ARVALIS. Its objective is to provide an overview (by disease and mode of action) of resistance to fungicides used on straw cereals, and to make recommendations with regard to these resistances with the aim of reducing and optimising fungicide treatments. The recommendations made in this memo encourage the use of prophylaxis, resistant varieties and decision support tools, to limit the use of treatments. National surveillance plans (DGAL, Arvalis performance network, etc.) and field data were used, among other things, to draft this memo.
The note indicates that, concerning SDHI (Succinate DesHydrogenase Inhibitors), the proportion of resistant strains of Zymoseptoria tritici remains stable (average frequency 36%), the resistance of Pyrenophora teres is overall generalized, while those of Puccinia triticina, P. striiformis and P. hordei seem to progress at varying frequencies depending on the species and region.
For Zymoseptoria tritici, it seems that resistance to SDHI is responsible for drop of efficacy, while for Pyrenophora teres the loss of efficacy is obvious, and more or less serious depending on the frequency and nature of the resistant strains present. A drop of efficacy for several SDHIs was also observed on brown rust of wheat in some regions.
It is therefore recommended to limit the use of SDHIs to a single application per campaign, all diseases combined, to diversify the modes of action, and to favor multi-site and/or bio-fungicides when they can improve the efficacy and/or the resistance management.
To download (in French):
Note commune 2026 INRAE/ANSES/ARVALIS – fongicides céréales à paille
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