Source and spread of fungal pathogens causing crown rot disease in organic bananas

Bananas are harvested while still green and many packaging processes are carried out until arriving to the market. Preparing banana hands by dividing the big cluster (dehanding), then cleaning and removing the accumulated latex (delatexing) that exudes directly after trimming the crown tissues. One of the most important postharvest disease affecting bananas during this stage is crown rot. The infection mainly occurs at harvest time, but the symptoms appear after overseas transportation. It is a complex disease where different fungal pathogens are involved and varying from one region to another. The use of synthetic fungicides to control such a disease is restricted and regulated in organic production. Over a period of two years (2013-2014), samples were collected directly on site in Dominican Republic from five different organic banana plantations and their corresponding packing stations, as symptomless samples covering all steps. A total of 3181 fungal colonies were obtained from crown tissues and 600 representative colonies were purified, characterized, and identified using morphological and molecular methods. Fungi were found in all analyzed samples representing eleven genera and the etiological agents of crown rot on organic banana were mainly Fusarium (38%), Colletotrichum (10%) and, Lasiodiplodia (2%). Fungi were isolated in high rate from flowers as well as crown parts, mainly occupied external part but some of them were isolated from the inner tissues. The diffusion of pathogens occurs when the bananas are processed through the dehanding and washing tanks. The final crown trimming followed by washing step and the application of protective products are the critical points.