Authors
Dai Kusumoto, The University of Tokyo Tanashi Forest, Graduate School of Agricultural and Life Sciences, the University of Tokyo, 1-1-8 Midori-cho, Nishi-tokyo, Tokyo 188-0002;
Hayato Masuya, Tohoku Research Center, Forestry and Forest Products Research Institute, 92-25 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate 020-0123, Japan;
Toshihide Hirao, The University of Tokyo Chichibu Forest, Graduate School of Agricultural and Life Sciences, the University of Tokyo, 1-1-49 Hinoda-machi, Chichibu, Saitama 368-0034, Japan;
Hideaki Goto, Kyushu Research Center, Forestry and Forest Products Research Institute, 4-11-6 Kurokami, Chuo-ku, Kumamoto 860-0862, Japan;
Keiko Hamaguchi, Kansai Research Center, Forestry and Forest Products Research Institute, 68 Nagaikyutaro, Fushimi-ku, Kyoto 612-0855, Japan;
Wen-I Chou, Department of Life Science, National Taitung University, No. 684, Sec. 1, Zhong-Hua Rd., Taitung 95002, Taiwan;
Wiwat Suasa-ard, Department of Entomology, Kasetsart University, KamphaengSaen, Nakhon Pathom 73140, Thailand;
Sawai Buranapanichpan, Faculty of Agriculture, Chiang Mai University. Chiang Mai 50200, Thailand;
Sopon Uraichuen,
Oraphan Kern-asa, and
Sunisa Sanguansub, Department of Entomology, Kasetsart University;
Aumporn Panmongkol, Doi Suthep-Pui National Park Office, Chiang Mai 50200, Thailand;
Quang Thu Pham, Vietnamese Academy of Forest Science, Dong Ngac, Tu Liem, Hanoi, Vietnam;
Sih Kahono, Museum Zoologicum Bogoriense, Division of Zoology, and
I Made Sudiana, Microbiology Division, Research Center for Biology, LIPI, JL. Raya Jakarta–Bogor Km.46, Cibinong, Bogor 16911, Indonesia; and
Naoto Kamata, The University of Tokyo Chichibu Forest, Graduate School of Agricultural and Life Sciences, the University of Tokyo
Abstract
The mass mortality of oak trees has been prevalent in Japan since the late 1980s. The fungus Raffaelea quercivora is transmitted by an ambrosia beetle, Platypus quercivorus, which causes mortality. The beetle is able to bore galleries into the sapwood of most Fagaceae trees in Japan; however, the level of mortality caused by R. quercivora and P. quercivorus differs greatly among tree species. Previous studies by our research group have demonstrated that the virulence of R. quercivora differs among isolates when inoculated into Quercus serrata logs. However, interactions between the virulence of R. quercivora isolates and the susceptibility of other fagaceous species have yet to be elucidated. In this study, we inoculated the fresh logs of 11 fagaceous species with isolates of low and high virulence, and measured the tangential widths of discolored sapwoods 3 weeks after inoculation. Although the discoloration widths of Q. crispula sapwood were similar among all isolates, those of Q. serrata and Q. acutissima tended to increase with the more virulent isolates. Sapwood discoloration in Q. glauca, Q. acuta, Q. salicina, Lethocarpus edulis, and Castanopsis sieboldii was greatly increased by highly virulent isolates. Discoloration in Fagus japonica was not influenced by any of the isolates. The logs of Q. crispula and Q. serrata but not Q. glauca were significantly more discolored by a low-virulence isolate compared with standing trees. The various virulent isolates induced unique sapwood discoloration characteristics in each species, which may explain species-specific differences in mortality rates.
