Crown Rot of Strawberry (Fragaria ananassa) Caused by Phytophthora cactorum

Phytophthora cactorum에 의한 딸기 역병

A severely wilting of strawberry caused by a Phytophthora sp. has occurred houses after planting in vinyl-houses field at Ssanglim and Anlim areas Kyungbuk in Korea from October in 1997. Phytophthora sp. isolated from diseased tissues of the crown of strawberry. Browning rot of inner crown and root resulted in wilt and eventual death of the plant. The causal fungus was identified as Phytophthora cactorum. Sporangia were ovoid, conspicuously papillate, caducous and measured 30.0~56.6$\times$23.8~35.2 (av. 39.3~29.9) ${\mu}{\textrm}{m}$. Sexuality of the fungus was homothallic. Oogonia were sperical and 23.3~32.3 (av. 29.0) ${\mu}{\textrm}{m}$ in size. Most ahteridia were paragynous and measured av. 10.2~12.2 ${\mu}{\textrm}{m}$. Cardinal temperature for growth at minimum, optium, maximum were recorded at 7, 20~25, and 32$^{\circ}C$, respectively. The fungus show strong pathogenicity to strawberry. This is the first report of strawberry caused by Phytophthora cactorum in Korea.