Isolation and identification of pathogenic fungi from postharvest blueberry in Sichuan province and the inhibition effect on them by using essential oil

Abstract

Objective: This study aimed to provide strategy for controlling the fungal diseases of postharvest blueberry in Sichuan province. Methods: The pathogenic bacteria from 14 planting bases in Sichuan Province were isolate, identified, pathogenicity determination. Moreover, the effects of temperature and light on mycelia growth of the dominant and subdominant strains of blueberry after harvest were studied, and the effective natural antibacterial components against them were screened. Results: The blueberry postharvest rot diseases were caused by the following nine kinds of fungi: Aspergillus niger, Aspergillus tubingensis, Neofusicoccum parvum, Neopestalotiopsis sp., Fusarium graminearum, Alternaria alternata, Mucor fragilis, Penicillium sp., Cladosporium xylophilum. Aspergillus niger was the dominant species with the highest isolation frequency and the most pathogenic, and Neopestalotiopsis sp., Alternaria alternata, Penicillium sp., Cladosporium xylophilum were the subdominant species with isolation frequencies greater than 10%. The optimum growth temperature ranged from 20 ℃to 35 ℃of dominant and subdominant strains of blueberry postharvest. The effects of light on the mycelia growth of A. niger，Neopestalotiopsis sp., A. alternata, and C. xylophilum were significant，but that was insignificant on the growth of Penicillium sp. strains. Thymol showed good broad-spectrum antibacterial activity, the EC50 values of dominant and subdominant strains of blueberry postharvest was 30~50 mg/L, while the thymol applied directly to blueberry postharvest fungal control in aqueous solution should not be higher than 50 mg/L. Conclusion: Thymol is more effective on postharvest diseases of blueberry in Sichuan province.

Keywords

• blueberry
• post-harvest diseases
• pathogenic fungus
• antifungal activity
• essential oil composition