Phytophthora Rot on Sword Bean Caused by Phytophthora nicotianae

Kwon, Jin Hyeuk; Lee, Hyeong Jin; Shen, Shun Shan; Park, Chang Seuk

doi:2004.20.4.235

Plant Pathol J > Volume 20(4); 2004 > Article

The Plant Pathology Journal 2004;20(4):235-239.
DOI: https://doi.org/10.5423/PPJ.2004.20.4.235 Published online December 31, 2004.

Phytophthora Rot on Sword Bean Caused by Phytophthora nicotianae

Jin Hyeuk Kwon, Hyeong Jin Lee, Shun Shan Shen, Chang Seuk Park

Abstract

Phytophthora rot on sword bean, Canavalia gladiata, which has not been reported yet in Korea, occurred in some fields of Jinju in 2003. The disease develops on the basal stem of the plant, but is also often observed on leaves and pods. Rot lesions begin with small dark brown spots and as these are water-soaked, they enlarge rapidly. The magnitude of at the field reached 40%. Abundant sporangia of Phytophthora were formed on the surface of diseased pods and were mummied later. The causal fungus was identified as P. nicotianae with the following mycological characteristics: Sporangiumreadily formed in water, papillate, noncaducous, ovoid to spherical, 24-58 (L) × 22-35 (W) in size; Oogoniumspherical, smooth walled, and 22-30; Oospore- aplerotic, spherical, and 18-24; Antheridium- amphigynous, unicellula, and spherical; Chlamydospore- abundant, spherical, and 25-35; Sexuality- heterothallic, and A1 or A2; Optimum growth temperature- about 28˚C. The fungus showed strong pathogenicity to sword bean. Symptoms similar to those observed in the fields appeared 2 days and 4 days after inoculation with and without wound on pods. This is the first report of Phytophthora rot of sword bean in Korea.

Key Words: Phytophthora rot, Phytophthora nicotianae, sword bean