International Symposium on Cereal Leaf Blights 2019 | University College Dublin, Ireland | 22-24 May 2019

RESIST – a multifacetated approach to manage the fungicide resistance of Zymoseptoria tritici in Belgian fields

Pierre Hellin*
Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Gembloux, Belgium

Aurélie Clinckemaillie
Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Gembloux, Belgium

Anne Chandelier
Pest Biology and Biovigilance Unit, Walloon Agricultural Research Center, Gembloux, Belgium

Anne-Sophie Walker
UMR 1290, INRA, AgroParisTech, Université Paris-Saclay, F-78850 Thiverval-Grignon, France

Steven Kildea
Department of Crop Science, TEAGASC Crops, Environment and Land Use Programme, Oak Park, Carlow, Republic of Ireland

Anne Legrève
Applied Microbiology, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium

Maxime Duvivier
Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Gembloux, Belgium

Poster Presentation
Cultural Management, Fungicide Resistance and Epidemiology

Atrium, UCD O'Brien centre for Science
Poster 15

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Owing to a lack of resistant varieties, fungicide application remains a key to prevent Septoria leaf blotch (STB) epidemics, caused by Zymoseptoria tritici. While continuous monitoring of fungicide resistance are performed annually in neighboring countries, no information was available regarding the current status of Z. tritici fungicide resistance in Belgium. In the framework of the RESIST project, a number of different approaches are undertaken to overcome this lack of knowledge. A first effort aimed at readily determine the spatial distribution of resistance of Z. tritici in commercial fields from the south of Belgium using a population-based method developed by INRA-BIOGER. These results are complemented with results from microtiter plate assays performed on single-spore isolates. The relatively high frequency of Multidrug Resistance (MDR) strains and of strains highly resistant to demethylation inhibitors (DMI) was comparable to the situation observed in the North of France. As expected, populations were also virtually insensitive to quinone outside inhibitor (QoI) and methyl benzimidazole carbamate (MBC) fungicides, while resistance to succinate dehydrogenase inhibitors (SDHI) is still low. A drastic increase in resistance from a 2008-09 baseline population was also observed for multiple active ingredients. The use of allele-specific qPCRs on leaf samples and classic sequencing on pure strains confirmed the presence of multiple resistant genotypes. Moreover, microtiter plate assays are performed to evaluate the evolution of the fungicide sensitivity of Z. tritici field populations resulting from different fungicide programs commonly used in Belgium. To further investigate the extent of the fungicide-driven selection in the field, an in vitro procedure is being developed to replicate and study the effect of field treatments. A comprehensive review of these results as well as their implication on future management of Z. tritici resistance will be elaborated.