Deciphering the magnitude and the time of action of weather factors on the allo-inoculum dynamics of Pseudocercospora fijiensis in Martinique.

Allo-inoculum has an important role in fungal disease epidemiology. Understanding the factors that impact the long-distance dispersal of a pathogen is crucial to improve its management. In this study, we studied Pseudocercospora fijiensis allo-inoculum dynamics in Martinique, over a period of 18 months. We used trap plants to measure (10 times) the spore abundance across six locations. Lesion densities observed on trap plants were used as a proxy of the allo-inoculum resulting from long dispersal ascospores. We analysed how the lesion densities of P. fijiensis measured with trap plants were statistically correlated with i) weather factors, and ii) the stage of evolution of disease (SED) measured in closest banana plots. The SED measured in neighbouring plots did not significantly influence the lesion densities observed on the trap plants. For each variable, we determined the period of time prior to the trap plants exposure that exhibited the strongest correlation with the lesion densities measured on these plants. Rainfall was the variable with the most influence and positively correlated with lesion densities when measured 7 to 4 days before trap plants exposure. Inversely, there was a negative correlation with UV radiation measured 2 to 1 days prior trap plants exposure. This information complements the knowledge on the biology of the fungus and holds potential for enhancing disease management, especially the importance of rainfall for the allo-inoculum dynamics. These results also showed that if commercial farms have a good management of BLSD, it does not contribute to long distance contamination.