Black Leaf Streak Disease (BLSD) is the most important foliar disease affecting Caribbean and worldwide banana production. This foliar disease is caused by the fungal pathogen Mycosphaerella fijiensis. In the absence of suitable control, yield loss represents from 20% to 80% of the production. However, the most important effect of BLSD is the reduction of fruit green-life, which can cause fruit ripening during the maritime shipping. In the Caribbean, BLSD was first reported in Cuba (1992), then in Jamaica (1994) and Dominican Republic (1996). More recently, the disease has been reported in Saint Vincent (2009), Saint Lucia (2010), Martinique (2010), Guadeloupe (2012) and Dominica (2012). A warning system has been developed and implemented in various countries aiming at optimal control of BLSD through minimum applications of fungicides (7-12). This system relies on adequate timing of fungicide applications and the use of systemic fungicides in mineral oil to ensure a high curative effect. However, the regular and intensive use of systemic fungicides can led to the emergence of resistant strains in M. fijiensis. Consequently, the implementation of the forecasting system has to be conducted in three steps. Firstly, initial fungicide resistance monitoring must be carried in order to evaluate the status of fungicide resistance in fungal populations and to adapt fungicide use. Secondly, the forecasting system should be adapted through field trials in commercial farms. Thirdly, for an optimal control of BLSD, the method should be implemented on a larger scale. Monitoring of fungicide resistance strains in M. fijiensis has been conducted in Martinique, Guadeloupe, Saint Lucia, Dominica and Dominican Republic (2010 to 2014). In the islands were M. fijiensis was recent (St Vincent, St Lucia, Martinique, Guadeloupe, Dominica) no resistance to any of the systemic fungicides (antimitotics, DMI, QoI) was detected in fungal populations. Conversely, in Dominican Republic, high leve