Brown root rot of trees caused by Phellinus noxius in the Ryukyu Islands, subtropical areas of Japan.

The fungus Phellinus noxius has a broad host range and causes brown root rot in a variety of tree species of various ages, irrespective of their original health. The fungus is widely distributed in tropical countries of Southeast Asia, the Pacific Islands and Australia, Central America and Caribbean, and Africa. Since 1988, when brown root rot was first found on Ishigaki Island, Okinawa Prefecture, the disease has been reported on several islands in Okinawa and Kagoshima Prefectures, and it has been causing serious problems to shade, windbreak, ornamental and landscape trees in the Ryukyu Islands, located in the subtropical region of southern Japan. Here, we report on the current status of P. noxius-caused brown root rot in the Ryukyu Islands, Japan, including symptoms, occurrence, dispersal, distribution and host tree species of the disease, pathogenicity and/or virulence of the pathogen, and disease management based on our surveys and previously published reports from Japan. Brown root rot has been confirmed in 53 tree species from 32 plant families at different sites on 10 of the 12 islands surveyed. Among the 53 tree species, 34 were first recorded in Japan as host plants of P. noxius. The disease occurs mainly in shade, ornamental and windbreak trees at sightseeing places, parks, roadsides, agricultural land such as sugar cane fields, and around residences or other places associated with human activities. [ABSTRACT FROM AUTHOR]