Phellinus noxius causes brown root rot on four important conifer species in Japan

The distribution of Phellinus noxius is currently limited to tropical and subtropical regions of Southeast and East Asia, Oceania, Central America, and Africa. The ability of this pathogen to produce disease in temperate climates is unknown. We examined the pathogenicity of Phellinus noxius on four important conifer plantation species grown under temperate conditions in Japan. The inoculation experiment with two isolates of P. noxius from Japan demonstrated clear fungal pathogenicity on the four conifer species, 3 months post-inoculation. Typical disease symptoms ranged from wilting, leaf chlorosis and necrosis, and defoliation resulting in the eventual death of most saplings. Mortality rate varied depending on tree species and the fungal isolate used. The results suggest that the possibility of serious damage if P. noxius invades the temperate zone of Japan (e.g., Kyushu and/or Honshu) from subtropical areas of Japan such as the Ryukyu Islands or foreign countries as global warming progresses.