Effect of storage temperatures on postharvest diseases of dragon fruit (Hylocereus undatus Haw.) in the Mekong Delta Region, Vietnam

This study was conducted to determine the effects of different storage temperatures and storage durations on postharvest diseases of dragon fruit grown in the Mekong delta region. Dragon fruit of uniform maturity and without defects were collected from two growers in Long An and Tien Giang provinces and stored at 0, 5 and 10°C for 21 and 26 days followed by storage at 20°C for 3 days to simulate shelf life in the market. Other fruit were harvested and held at 20°C for 7 and 12 days as a non-stored control. The proportion of fruit with rots and changes in bract appearance were recorded and analyzed. The results indicated that fruit stored at 0 and 10°C (for both 21-26 days), and the control fruit held at 20°C for 7 and 12 days sustained the most damage. The most common disorders were rots and wilting and colour change (yellowing) of the bracts. Fruits stored for 21 and 26 days at 6°C remained fresh in appearance and had significantly fewer rots. The pathogenicity of fungi isolated from the rots was confirmed by re-inoculation of healthy fruit and the pathogens identified by conventional and molecular methods. The main fungi associated with spoiled fruit were: Alternaria alternata, Aspergillus sp., Bipolaris cactivora, Cladosporium sp., Colletotrichum gloeosporioides, Colletotrichum truncatum, Fusarium andiyazi, Fusarium dimerum, Fusarium equiseti, Geotrichum candidum, Mucor sp., Neoscytalidium dimidiatum, Phomopsis longicolla, and Rhizopus stolonifer.