Raffaelea quercivora
A lethal disease of oak in Japan
Why: This disease came to our attention as high mortality of Quercus was reported in Japan. It was included on the EPPO Alert List in 1999 as ‘fungal oak disease’ and deleted in 2002 as no new information was available. However, because a possible causal agent has been identified (Raffaelea quercivora sp. nov.) and a high mortality is still observed in Japan, the EPPO Secretariat decided to include it again in the Alert List.
Where: Japan (Honshu, Kyushu).
 |
On which plants: Q. serrata and Q. crispula.
Damage: Since 1980, massive mortality of oak trees (more than 200,000 per year) has been observed in western coastal areas of Honshu. Mortality occurs during summer months. Prior to wilting, massive attacks by ambrosia beetles (Platypus quercivorus - Coleoptera: Platypodidae) and xylem discoloration are observed. Recent studies have shown that the cause of oak tree mortality is the blockage of the ascent of xylem sap induced by the fungus which is transmitted by the insect P. quercivorus.
Images can be viewed on the Internet at:
http://cse.ffpri.affrc.go.jp/keiko/hp/oak.html
http://cse.ffpri.affrc.go.jp/keiko/hp/oakwilting-overview.html.
Possible identity: Raffaelea quercivora sp. nov. (an anamorphic Ascomycete) was isolated from discoloured sapwood, necrotic inner bark, beetle body surfaces and galleries. Inoculation tests confirmed its pathogenicity to Q. acutissima and Q. crispula.
Pathway: Unknown (plants for planting? wood?).
Possible risks: Oaks are important forest and amenity trees in the EPPO region. Although a putative causal agent has been identified data is still lacking on the etiology of this disease (as several factors might be included, climatic factors, insects, fungus). Data is also needed on the susceptibility of European oaks.
Source(s)
Ito, S.; Murata, M.; Yamada, T. (2003) Massive mortality of Fagaceous trees in Japan. Abstract of a paper presented at the APS Annual Meeting (Charlotte, US, 2003-08-09/13). Phytopathology 93(6), supplement, S102.
Kinuura H, Kobayashi M (2006) Death of Quercus crispula by inoculation with adult Platypus quercivorus (Coleoptera: Platypodidae). Applied Entomology and Zoology 41(1), 123-128. http://www.jstage.jst.go.jp/article/aez/41/1/123/_pdf
Kobayashi M, Ueda A (2005) [Wilt disease of Fagaceae trees caused by Platypus quercivorus (Murayama) (Coleoptera: Platypodidae) and the associated fungus: aim is to clarify the damage factor.] Journal of the Japanese Forest Society 87(5), 435-450. (abst.)Kuroda, K. (1998) Determinant factor of oak mortality in Japan: xylem discoloration and dysfunction associated with beetle invasion and fungal infection. Abstracts of papers presented at the 7th International Congress of Plant Pathology, Edinburgh, GB, 1998-08-09/16 (Abst. 3.7.16).
Kuroda K (2001) Responses of Quercus sapwood to infection with the pathogenic fungus of a new wilt disease vectored by the ambrosia beetle Platypus quercivorus. Journal of Wood Science 47, 425-429.
http://www.2006.botanyconference.org/engine/search/index.php?func=detail&aid=139&GetID=8
Murata M, Yamada T, Matsuda Y, Ito S (2007) Discoloured and non-conductive sapwood among six Fagaceae species inoculated with Raffaelea quercivora. Forest Pathology 37(2), 73-79.
INTERNET (last retrieved on 2007-04).
APHIS-USDA website
Davis ED, French S, Venette RC (2005) Mini risk assessment. Platypus quercivorus Murayama [Coleoptera: Platypodidae]. http://www.aphis.usda.gov/plant_health/plant_pest_info/pest_detection/downloads/pra/pquercivoruspra.pdf
Tokyo University Forests website
Defence responses of oak sapwood in relation to wilt of oak trees in Japan by Yamada T & Ichihara Y. http://www.uf.a.u-tokyo.ac.jp/research/yamada/nz.pdf
EPPO RS 99/027, 2003/067, 2007/070
| Panel review date 2007-03 | Entry date 1999-02 (deleted in 2002, added again in 2003) |