Stem rot of strawberry caused by Sclerotium rolfsii in Korea

Abstract

A destructive stem rot of strawberry (Fragaria × ananassa cv. Akihime) sporadically occurred in farmers' fields in Daegok-myon, Jinju city, Gyeongnam province in Korea. The infected plants showed stem and crown rot, with occasional blighting of the whole plant. White mycelia appeared on stems of infected clones and sclerotia formed on the old lesions near soil surface. The fungus formed white colony on PDA and showed maximum mycelial growth and sclerotial formation at 30°C. The fungus usually have many narrow hyphal strands, 2.6-10.0 μm in width, in the aerial mycelium. Typical clamp connections were formed on the mycelium. Sclerotia were spherical and 1.0-2.4 mm in size. The fungus was repeatedly isolated from infected tissues and identified as Sclerotium rolfsii. Its patho-genicity was confirmed when inoculated onto straw-berry. This is the first report on the stem rot of strawberry caused by S. rolfsii in Korea.