Occurrence of Rhizopus Soft Rot on Squash (Cucurbita moschata) Caused by Rhizopus stolonifer in Korea

season of 2000. The disease infection usually started from flower, peduncle and young fruits, then moved to flower stalk, stem and leaves. At first, the lesions started with water-soaked, rapidly softened, and then the area gradually expanded. In severely affected film house, the rate of infected fruits reached to 28.6%. Numerous sporangiospores were formed on the diseased fruits, flower stalk, stem and leaves. Most of the sporangiospores were appeare to be rapidly dispersed in the air. The mycelia grew on the surface of host and formed stolons. Colonies on potato dextrose agar were cottony at first brownish black at maturity. Sporangia were 125.3${\times}$294.2 ${\mu}$m. globose or sub-globose with somewhat flattened base. White at first the black, many spored, and are never overhanging. Sporangiophores were 2.7-6.8${\times}$12.9-33.9 ${\mu}$m, smooth-walled, non-septate, light brown, simple, long, arising in groups of 3-5 from stolons opposite rhizoids. Sporangiophores were 8.6-21.1${\times}$6.41-1.7 ${\mu}$m, irregular, round, oval, elongate, angular and brownish-black streaked. Columella were 63.8${\times}$140.4 ${\mu}$m. brownish gray, umberella-shaped when dehisced. The causal organism was identified as Rhizopus stolonifer Lind on the basis of the morphological characteristics of the fungus. Rhizopus soft rot on squash (Cucurbita moschata) caused by the fungi has not been previously reported in Korea.