A predictive model based on a pluviothermic index for leathery pocket and fruitlet core rot of pineapple cv. 'Queen'

Leathery pocket (LP) and fruitlet core rot (FCR) of pineapple (Ananas comosus L.) caused by Penicillium funiculosum Thom. and/or Fusarium moniliforme Sheld cause significant damage in all production areas, resulting in a major economic impact that affects both the fresh fruit market and the processing sector. The detection of Penicillium and Fusarium in the two main areas of pineapple production in Reunion Island, and representing a large range of climatic conditions, indicated that these fungi responsible for FCR and LP diseases were present throughout the pineapple cycle, whatever the climatic conditions. The proportion of fruits naturally infected by these pathogens was not related to climatic conditions during the infection period, suggesting that the inoculum level was not limiting. As these diseases cannot be reliably controlled, due in particular to the role of climatic conditions, an important research goal is to predict periods of higher disease risk using a model based on weather data. Taking advantage of the great diversity of environments on the tropical island of Reunion (Indian Ocean), we were able to establish a link between a pluviothermic index (PTi: ratio between total rainfall and the average temperature over the fruit development stages), and LP or FCR incidence. Disease incidence wasmodelled as a function of the pluviothermic index via a Weibull model. The most accurate model was obtained during the open heart to harvest stage. Lastly, the model output can be used by pineapple production stakeholders in farm management. (Résumé d'auteur