Development and detection of bacterial soft rot of Hosta spp. Tratt. caused by Erwinia carotovora subsp. Carotovora

Abstract

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 0°C 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 0°C. 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 0°C. Using polymerase chain reaction, specific primers ECC K and W were developed for the detection of E. carotovora subsp. carotovora.