Tunisian population of Mycosphaerella graminicola is still sensitive to strobilurin fungicides.

Septoria tritici blotch caused by the fungal pathogen Mycosphaerella graminicola (anamorph: Zymoseptoria tritici) is one of the most frequently occurring diseases on both bread and durum wheat crops worldwide. One hundred and sixty four durum wheat-adapted isolates of this fungus were sampled during the 2012 growing season from five distinct geographical locations of Tunisia (Bizerte, Béja, Kef, Jendouba and Siliana) in order to examine the status of strobilurin resistance of M. graminicola in this country. Resistance was assessed by screening the G143A substitution (Cytochrome b) which confers resistance to this class of fungicides. We used a PCR-based mismatch mutation assay allowing the amplification of either G143 (sensitive) or A143 (resistant) allele. All isolates were found to contain the sensitive wild-type G143 allele and therefore to be sensitive. Our study confirms recent reports on M. graminicola in Tunisia and shows that the Tunisian population of the fungus remains fully sensitive to strobilurins. A durability-oriented management of strobilurin applications in Tunisia is thereby recommended to prevent the development and widespread of the corresponding resistance such as in Europe, where pathogen populations are nowadays fully resistant to strobilurins.