Résumé
Black leaf streak disease (BLSD) is considered as the most destructive foliar disease of bananas and plantains. The disease is due to a fungus, Mycosphaerella fijiensis, spread by air and rain. Due to its recent and rapid worldwide invasion and its presence in the northern Caribbean islands since 90's, the risk of introduction in the Lesser Antilles was high. To prevent and/or to detect as early as possible the presence of the disease, scientific and technical efforts were deployed to set up, in the Lesser Antilles, some BLSD epidemiological surveillance networks in the framework of Caribbean Sustainable Banana Project. Since 2010, the activities consisted in different and complementary activities : (i) regional trainings on the BLSD diagnosis were organized by CIRAD and allowed to the still BLSD-free countries (St Vincent, St Lucia, Martinique, Dominica and Guadeloupe) to set up national BLSD vigilance and surveillance networks ; (ii) early official diagnoses were realized in the 5 countries ; (iii) the BLSD spatiotemporal spread was followed in each newly detected allowing to brake its expansion and to optimize control method particularly in bananas vitroplants nurseries and in export bananas plantations ; these surveillance completed with a modeling approach suggest that the invasion duration depends on the numbers of introductions, the efficacy of control methods and the spatial structure of bananas productions ; (iv) the reconstruction of the history invasion in the Caribbean through the molecular analyses of 1800 pathogenic isolates collected in 20 countries suggest the occurrence of 2 invasion pathways and two modes of introduction (human-mediated and natural introductions). All these BLSD epidemiological-surveillance networks in the Caribbean have allowed to detect as early as possible the presence of the disease in 5 countries of the Lesser Antilles and at present allow optimizing control practices. (Résumé d'auteur)