Center Rot of Onion

Center rot of onion, caused by the bacterium Pantoea ananatis, continues to be a problem in the production of Vidalia onions. The disease reduces both yield and quality of onion bulbs. Under certain conditions center rot infections will promote a soft rot of the bulb prior to harvest. Incidence and severity of center rot in Georgia in 2006 were the highest observed in the past five years. The Department of Plant Pathology at the Coastal Plain Experiment Station in Tifton has had a research program on center rot since 1999. During that time at least four research faculty members, two Cooperative Extension faculty members, two postdoctoral scientists, several county agents, technicians and part-time student laborers have spent a portion of their time conducting research on center rot of onion. Experiments in the lab, greenhouse and field were conducted to investigate the ecology of Pantoea ananatis and the epidemiology of center rot. In addition to conducting research, personnel of the phytobacteriology lab once again served as a resource for the state of Georgia by providing detailed identification of bacterial species submitted by growers, Extension specialists, county Extension agents, Georgia Department of Agriculture inspectors and private industry. Eventually, their findings could lead to a better formulation for one of the only pesticides labeled for control of bacterial diseases.