After Dijon, Brussels, Nancy, Marrakech, the fifth edition of the Francophone Days of Mycorrhizas (https://jfm2018.univ-littoral.fr/) will take place in Dunkerque at the University of Littoral Côte d’Opale (ULCO) from 26 to 28 June 2018. It’s the team IPCR (Plant-Mushroom Interactions and Remediation) of the UCEIV to the ULCO which will organize the JFM5. This symposium will present the latest scientific progress in the field of mycorrhizal symbiosis, mutual benefit associations between mycorrhizal fungi soil and the roots of the majority of plants. These interactions allow plants to improve the use of natural resources of the soil and to better respond to environmental constraints, both abiotic (pollution, drought, salinity, cold, …) and biotic (various phytopathogenic agents). The management and valuation of the ecosystem services rendered by mycorrhizae represent one of the major challenges for the qualitative and quantitative optimization of crop production and for the rehabilitation of degraded soils. Thus, at the time of sustainable development, mycorrhizae are considered as one of the key players in agro-ecology and phytomanagement of degraded sites and soils. (flyer).