Bioefficacy test of Hatake™ (Bacillus amyloliquefaciensD203 strain) for control of crown rot disease in ‘Cavendish’ bananas

Abstract

Postharvest diseases of bananas remain a significant challenge of banana exporting countries and can result in considerable losses. Adequate storage and transportation facilities are among the strategies employed to reduce losses, but chemical control has been found to be more effective and economical. Synthetic fungicides have traditionally been used to mitigate postharvest diseases caused by harmful microorganisms. However, with current global health concern, there is a public desire to utilize eco-friendly alternatives to address decay loss. A study on the bioefficacy of a commercial formulation containing Bacillus amyloliquefaciens strain D203 (Hatake™) for control of crown rot disease in 'Cavendish' bananas, was conducted using both in vitro and in vivo screening techniques. Its potential in controlling crown rot and the efficacy of different rates were determined. Crown rot causing microorganisms were isolated and tested for antagonism by B. amyloliquefaciens strain D203. Efficacy was assessed through observations on its antagonistic properties, crown rot and mould severity, crown discoloration and peel colour changes. Laboratory analysis indicated that Colletotrichum musae was the dominant microorganism that colonized the petri plate which was further proved through pathogenicity tests. 1.0 g mL(‑1) of Hatake™ showed higher inhibitory zones against C. musae. Furthermore, an in vivo experiment showed that 1.0 g mL(‑1) rate of Hatake™ was more effective than 0.5 and 2.0 g mL(‑1) and synthetic chemical treatment in controlling crown rot and mould formation or production. A 1.0 g mL(‑1) rate of Hatake™ resulted in better crown colour among all fruit treated with 103 inoculum of C. musae mL(‑1) water. Development of fruit ripening, as manifested by its peel colour change, was significantly slower in fruits treated with 1.0 g mL(‑1) of Hatake™ compared to all treatments innoculated with 103 inoculum of C. musae mL‑1 water. The results indicated that Hatake™ has the potential for commercial application as postharvest treatment for 'Cavendish' bananas.