Identification of Camellia oleifera anthrax pathogens in Yunnan Province and screening of antagonistic bacteria

Objective  In order to identify the species of pathogens of Camellia oleifera anthrax in Dehong Prefecture, Wenshan Prefecture and Baoshan City of Yunnan Province, and screen their biocontrol bacterium.

Method  Surveys of infected diseases were conducted from July to September in 2019 and 2020. Diseased leaf samples were collected. The pathogens were isolated by tissue isolation method, pathogenicity was verified by Koch’s Postulation, and the pathogens were identified by morphology and multilocus sequence analysis. Meanwhile, endophytic bacteria were isolated and screened from the leaves of healthy C. oleifera, and the antibacterial effect was verified by plate confrontation method.

Result  C. oleifera anthrax occurred seriously in Dehong Prefecture of Yunnan Province, with an average incidence rate of 56.18% and a disease index of 53.11. Five major strains were identified from Yunan Province including Colletotrichum gloeosporioides,C. kahawae, C. karstii, C. fiorniae and C. siamense. Among them, C. gloeosporioides was the dominant pathogen, and strain CA17 (C. siamense) had the strongest pathogenicity on living leaves of C. oleifera. The results of plate confrontation method indicated that Streptomyces fulvissimus and Bacillus mojavensis isolated from healthy C. oleifera in Dehong had good antagonistic effect on CA17, and the inhibition rates were 37% and 42% respectively.

Result  This study provides a theoretical basis for the diagnosis and green control of Camellia anthrax.