First report of canker disease in Dalbergia tonkinensis caused by Fusarium lateritium and Fusarium decemcellulare

Dalbergia tonkinensis is a precious tree species of high economic value. Due to an increase in planting activities in the past few years in Vietnam, the provision of healthy planting stock is in high demand. Canker disease, which can affect the growth and quality of the plant, has been found to occur on scattered old trees and in D. tonkinensis plantations. This study aimed to identify symptoms, and to characterize the morphology, taxonomy and pathogenicity of Fusarium pathogens causing canker disease in D. tonkinensis in North Vietnam. Typical symptoms of disease caused by Fusarium spp. in D. tonkinensis included stem and branch canker, and darkening of the wood, leading to the canopy on diseased stems becoming yellow, followed by wilting, drying and premature leaf fall. From ITS1 and ITS4 sequence analysis, the Fusarium isolates causing canker disease in D. tonkinensis in Vietnam belong to Fusarium decemcellulare and Fusarium lateritium. These species were pathogenic in inoculation trials using detached branches and seedlings. The pathogenicity of isolates ranged from moderate to highly virulent. In conclusion, canker disease caused by F. lateritium and F. decemcellulare is quite common in North Vietnam, and options for disease management need to be developed in further domestication of this threatened species