Integrated control of crown rot of banana with Candida oleophila strain O, calcium chloride and modified atmosphere packaging

An integrated approach for biological control of crown rot of banana was studied. The efficacy of three control measures, applied alone or in various combinations, was evaluated under conditions highly conducive to the development of crown rot (artificial inoculation of Colletotrichum musae at 104 conidia/ml). The studied measures were: application of an antagonistic yeast (Candida oleophila strain O at 1.107 cfu/ml), treatment with 2% (w/v) calcium chloride, and modified atmosphere packaging of fruit (MAP) in non-perforated polyethylene bags. C. oleophila was able to grow under MAP, maintaining a large population (7.106 to 7.107 cfu/g crown) throughout the 13 days of storage. Both treatment with the antagonistic yeast and storage under MAP, applied separately, reduced crown rot significantly (by 22% and 20%, respectively, as compared to untreated controls). The effect of the yeast was the same whether it was produced in Petri dishes or in a fermentor. Calcium chloride treatment alone had no effect on C. musae. The antagonistic yeast showed a 16% higher biocontrol activity (from 26% to 42%) when applied together with 2% (w/v) calcium chloride, and the presence of this adjuvant made it possible to achieve the same protective effect with a lower yeast concentration. The highest efficacy (53%) was achieved by the combination of the three alternatives means of control and a synergistic relation has been detected between the yeast, calcium chloride and MAP. Considering the severe conditions of screening, the consistency of the results obtained in this study indicates that the integrated strategy has great potential for control of crown rot of banana under commercial conditions.