A soft rot of hosta, caused by an unknown agent, was observed at a large wholesale nursery in South Carolina in 1999. Losses ranged between 80 and 90 percent in the cultivated varieties Aureo-marginata and Golden Tiara that had been chilled at 0C in a refrigerated storage facility for 8-16 weeks to fulfill dormancy requirements. The causal agent of bacterial soft rot of hosta was determined to be Erwinia carotovora subsp. carotovora. Hosta plants spray-inoculated with suspensions of E. carotovora subsp. carotovora developed soft rot following 24 hours cold storage at 0C. Spread of disease occurred during cold storage of dormant hosta rhizome divisions and through vegetative propagation. Bactericides and disinfectants tested were ineffective when used as a protectant prior to exposure to 0C. Using polymerase chain reaction, specific primers ECC K and W were developed for the detection of E. carotovora subsp. carotovora.