Pathogen. The aerial stem rot bacterium is soil- borne. Contaminated surface water is an important source of infection.
Disease development. Incidence of this disease is high in wet seasons. Stems, petioles and leaves become infected through natural openings, such as leaf scars or wounds, caused by hail, wind-blown sand or farm equip- ment. The infection extends up and down the stem from the point of infection. Infection can spread through the stems and stolons to daughter tubers, causing symptoms similar to blackleg. These infected daughter tubers begin to rot either in the field or later during storage.
