Introduction
Phytophthora katsurae
W. H. Ko & H. S. Chang (1979)
Phytophthora castaneae
Katsura & Uchida (1976) (Katsura, 1976), a synonym for P. katsurae, was
isolated from diseased chestnuts (Castanea crenata) in
Cultural Characteristics
The minimum temperature for growth is 9°C, the optimum temperature for growth is 27°C, and the maximum temperature for growth is 32°C (Fig. 2).
Reproductive Structures
Asexual Structures
Sporangiophores:
Sporangiophores do not branch. Sporangia are sometimes in a tight sympodium.
Sporangia:
Sporangia are mostly terminal, although they sometimes form laterally or intercalarily. Sporangia are limoniform, ovoid, obpyriform to obturbinate, and papillate, sometimes with multiple papillae. Sporangia are 10–37.5 × 10–42.5 µm (average 22.5 × 27.5 µm) (Fig. 3).
Chlamydospores:
Chlamydospores are 12–19.2 µm in diameter and spherical.
Sexual Structures
P. katsurae is homothallic.
Antheridia:
Antheridia are amphigynous and spherical to ovoid.
Oogonia:
Oogonia are 19–31 µm in diameter. Oogonia have warty or bullate protuberances on the surface and a distinct funnel-shaped base.
Oospores:
Oospores are 15–27.5 µm in diameter
(average 20 µm) (Fig.
4). Oospores are markedly
aplerotic.
Host Range and Distribution
Host |
Common Name |
Disease |
Geographical Distribution |
Castanea crenata |
Chestnut |
Trunk rot |
|
Cocos nucifera |
Coconut |
Fruit and heart rot |
|
Theobroma cacao |
|
Pod rot |
|
Symptoms
Trunk Rot of Chestnut:
Lesions develop 10–100 cm aboveground. The bark around the infected area begins to soften and fissures develop around the lesions. These fissures are covered with a black exudate that has a fermentation odor. Bark quickly dies. The infected tree normally dies within 4 years of infection (Erwin and Ribeiro 1996).
Fruit Rot of Coconut:
References
Clements, F. E., and Shear, C. L. 1931. The Genera of Fungi. H. W. Wilson Co.,
Elliott, M. L., Broschat, T. K., Uchida, J. Y., and Simone, G. W., eds. 2004. Compendium of Ornamental Palm Diseases and Disorders. American Phytopathological Society, St. Paul, MN.
Erwin, D. C., and Ribeiro, O. K. 1996.
Phytophthora
Diseases Worldwide. American
Phytopathological Society,
Katsura, K. 1976. Two new species of Phytophthora causing damping-off of cucumber and trunk rot of chestnut. Trans. Mycol. Soc. Jpn. 17:238-242. (In Japanese)
Ko, W. H., and Chang, H. S. 1979. Phytophthora katsurae, a new name for P. castaneae. Mycologia 71:840-844.
Stamps, D. J. 1985. Phytophthora katsurae. CMI Descr. Pathog. Fungi Bact. 837.
Uchida, J. Y., Aragaki, M., Ooka, J. J., and Nagata, N. M. 1992.
Phytophthora fruit and heart rots of coconut in
Waterhouse, G. M. 1963. Key to the species of
Phytophthora de Bary. Mycol. Pap. 92. CAB
International, Wallingford, United Kingdom; Commonwealth Mycological Institute,
Kew,