The influence of alum, bicarbonate, and chlorine treatments on crown rot disease progress in organic bananas

Crown rot is a post-harvest fungal disease causing a great negative impact on fruit quality. The infection mainly occurs by different etiological agents at harvest time but the symptoms appear after 10-14 days later, usually after overseas transportation. The use of synthetic fungicides to control this disease is restricted and regulated in organic farming. Therefore, it is necessary to find safe alternatives to fungicides useful to reduce the incidence under acceptable threshold levels. The effect of alum, bicarbonate, and chlorine on crown rot disease progress was assessed on organic bananas in some pathogen strains. In vitro, mycelium and conidia of strains belonging to the main fungal species identified as etiological agent of crown rot in Dominican Republic were assessed for the germination and growth against different concentrations of the substances to report their activity as fungicidal/fungistatic on artificial media and crown tissues. Results obtained were corresponding to those reported in disease incidence, whereas the alum mainly acts as fungistatic, the chlorine was fungicidal, and sodium bicarbonate didn't demonstrate effect on conidia germination at the tested concentration. In packing stations, 240 hands of banana were used immediately after the second washing bath in three separate treatments; 1) alum as normally adopted in packing stations, 2) 5 g/L of sodium bicarbonate in water, and 3) 3 ppm chlorine in water. The results showed significant differences between the different treatments. Sodium bicarbonate improved the infections causing highest disease incidence 81%, followed by alum with 23%. In contrast, no symptomatic fruits were present among bananas treated with chlorine.