INTEGRATED CONTROL OF CROWN ROT DISEASE IN 'KLUAI HOM THONG' BANANA

Collectotrichum musae, Lasiodiplodia theobromae and Fusarium spp. are the causal agents of banana crown rot disease, a major problem for domestic and export markets. Combined effects of heated potassium sorbate (PS) treatment with modified atmosphere packaging on the control of crown rot disease were investigated. ‘Kluai Hom Thong’ bananas were harvested from Good Agricultural Practices (GAP) orchards. Banana crowns were inoculated with a mixture of three spore suspensions of the above mentioned pathogens for 6 h before the banana hands were immersed in hot water (HW) at 45°C for 20 min or in a heated solution of 0.5% (w/v) PS at 45°C for 20 min. All treated banana hands were packed into perforated polyethylene (PPE) bags or active packaging (AP, M4 film) bags. Banana hands were treated with 500-ppm thiabendazole (fungicide) for 20 min, then packed in PPE bags were used as the control. All treated banana hands were stored in a cold room at 13°C for 28 days to simulate storage life, then transferred to an ambient temperature of 25±2°C for 3 days to simulate shelf life. Disease severity and quality of bananas were then determined. The heated PS solution treatment delayed the severity of crown rot disease, as did the thiabendazole treatment, up to 21 days at 13°C only, whereas banana hands treated with HW prior to packing in PPE or AP bags showed the highest disease severity throughout storage and shelf life. Retardation of disease severity using heated PS treatment and thiabendazole was related to increased chitinase activity, while the activities of peroxidase (POD) and polyphenol oxidase (PPO) were not significantly different among treatments. The AP bags had the ability to delay banana ripening as evidenced by maintained flesh firmness and delayed changes in peel colour and total soluble solids content. This was particularly in the heated PS solution treatment, which showed the greatest effect in delaying banana ripening.