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Introduction. Black Leaf Streak Disease (BLSD) is regarded as the most economically important threat that the banana industry has to face. Effectively, this foliar disease affects leaf photosynthesis but, above all, reduces the greenlife of fruits, that cannot be exported in cases of severe infestation. Main characteristics of Black Leaf Streak Disease. More than 20 Mycosphaerella species have been described on bananas. Leaf spot diseases of bananas are caused by some species of this complex, of which M. fijiensis (BLSD) and M. musicola (Sigatoka disease) are the most important. M. fijiensis is an invasive species that has totally replaced M. musicola in most banana-exporting countries, which was conducive to increasing difficulties in banana leaf spot control. BLSD causes increasing difficulties for control. Since all banana cultivars grown in the banana industry are highly susceptible to BLSD, the control of this disease relies on aerial applications of fungicides according to either systematic frameworks (mostly contact fungicides) or forecasting strategies (mostly systemic fungicides). In a banana-exporting country where M. fijiensis has been reported, BLSD control becomes increasingly more difficult. This evolution is essentially due to the rapid emergence of fungicide resistance, and is conducive to a significant increase in the cost of disease control but, above all, to increasing negative environmental effects. Challenges for the banana industry. Because of the rapid adaptation of M. fijiensis, the banana industry must be prepared for significant evolution. We propose various parameters that should be monitored at different levels (disease assessment parameters, evaluation of chemical control efficiency, global evaluation of BLSD economic incidence) to rationalize such evolution. The modelization of BLSD effects on bunch mass and greenlife should enable defining acceptable disease thresholds and optimizing bunch weight and harvest stage according to agronomic practices. On the other hand, fungicide use is conducive to significant environmental impact and must be limited. Forecasting strategies should be used wherever systemic fungicides are still efficient. Finally, the predominance of a unique type of susceptible cultivar is unsustainable and the recourse to resistant varieties in an integrated strategy is undoubtedly the future of BLSD control. [ABSTRACT FROM AUTHOR]

Introduction. This protocol aims to diagnose under laboratory conditions the main Mycosphaerella spp. pathogens of bananas and plantains. The three pathogens Mycosphaerella fijiensis (anamorph Paracercospora fijiensis), M. musicola (anamorph Pseudocercospora musae) and M. eumusae (anamorph Pseudocercospora eumusae) are, respectively, the causal agents of Black Leaf Streak disease, Sigatoka disease and Eumusae Leaf Spot disease. The principle, key advantages, starting plant material and time required for the method are presented. Materials and methods. The laboratory materials required and details of the thirteen steps of the protocols (tissue clearing and in situ microscopic observations, isolation on artificial medium and cloning of single-spore isolate, in vitro sporulation and microscopic observations of conidia, and long-term storage of isolates) are described. Results. Diagnosis is based on the observations of anamorphs (conidiophores and conidia) which can be observed directly from banana leaves or after sporulation of cultivated isolates if sporulating lesions are not present on banana samples. Introduction. Le protocole vise ? diagnostiquer, en laboratoire, les principales esp?ces de Mycosphaerella pathog?nes des bananiers et plantains. Les trois agents pathog?nes Mycosphaerella fijiensis (anamorphe de Paracercospora fijiensis), M. musicola (anamorphe de Pseudocercospora musae) et M. eumusae (anamorphe de Pseudocercospora eumusae) sont respectivement responsables de la maladie des raies noires, de la maladie de Sigatoka et de la cercosporiose due ? eumusae. Le principe, les principaux avantages, le mat?riel v?g?tal et le temps n?cessaires ? la m?thode sont pr?sent?s. Mat?riel et m?thodes. Le mat?riel de laboratoire n?cessaire et le d?tail des treize ?tapes de r?alisation du protocole (pr?l?vement des tissus et observations microscopiques in situ, isolement sur milieu artificiel et clonage d?isolats monospor?s, sporulation in vitro et observations microscopiques des conidies, conservation ? long terme des isolats) sont d?crits. R?sultats. Le diagnostic est bas? sur les observations des anamorphes (conidiophores et conidies) qui peuvent ?tre observ?s directement ? partir des feuilles de bananes ou apr?s sporulation des isolats mis en culture s?il n?y a pas de l?sions sporulantes sur les ?chantillons de bananiers. [ABSTRACT FROM AUTHOR]

Introduction. This protocol aims at (i)?analysing the nature of host-parasite interactions (resistance or susceptibility), and (ii)?studying the variability of the pathogenicity of different pathogen populations (intra/inter-specific) with regard to both virulence and aggressiveness using artificial inoculation with Mycosphaerella fijiensis or Mycosphaerella musicola on plants and banana leaf pieces. The principle, key advantages, starting plant material and time required for the method are presented. Materials and methods. Laboratory materials required and details of the sixteen steps of the protocol (conidial inoculum preparation, artificial inoculation on banana plants and artificial inoculation on banana leaf pieces) are described. Possible troubleshooting is discussed. Results. Typical symptoms of the different diseases are obtained after artificial inoculation.Introduction. Ce protocole vise (i) ? analyser la nature des interactions h?tes-parasites (r?sistance ou sensibilit?), (ii) ? ?tudier la variabilit? de la pathog?nicit? de diff?rentes populations pathog?nes (intra/intersp?cifiques) quant ? leur virulence et leur agressivit? mesur?es ? partir d?'inoculation artificielle avec Mycosphaerella fijiensis ou Mycosphaerella musicola sur des plants et des morceaux de feuille de bananier. Le principe, les principaux avantages, le mat?riel v?g?tal de d?part et le temps n?cessaire de la m?thode sont pr?sent?s. Mat?riel et m?thodes. Le mat?riel de laboratoire n?cessaire et le d?tail des seize ?tapes de r?alisation du protocole (pr?paration de l'inoculum conidial, inoculation artificielle sur des plants de bananier, et inoculation artificielle sur des morceaux de feuille de bananier) sont d?crits. Des probl?mes potentiels sont ?voqu?s. R?sultats. Des sympt?mes-types de la maladie sont obtenus apr?s inoculation artificielle. [ABSTRACT FROM AUTHOR]