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 before coming on the market; starting with preparing banana hands by dividing the big cluster (dehanding), then cleaning and removing the accumulated latex (delatexing) after trimming the crown tissues. Crown rot is the most important postharvest disease affecting bananas. 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. This study searched for critical points of crown rot infections along the processing steps in organic farming, where the use of synthetic fungicides is restricted and regulated. Samples were collected in the Dominican Republic from five different organic banana plantations and their corresponding packing stations. Covering all packing steps, a total of 1495 fungal colonies were obtained from symptomless crown tissues. Whereas, 270 representative colonies were purified, characterized and identified using morphological and molecular methods. Fungi associated with crown rot disease were found in all analyzed samples dominated by Fusarium (47%), followed with Lasiodiplodia (7.4%) and Colletotrichum (1.1%). Fungi were isolated in high rate from flowers as well as crown parts. 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 focusing on water quality, are the critical points.