These water-soaked lesions rapidly turn brown and with aging may dry out and become papery and tan. On greenhouse transplants, bacterial blight lesions may develop extensively on the foliage. However, in the field the disease usually is found only on the older leaves that are protected by the plant canopy, except where sprinkler irrigation is used. Once introduced into transplant greenhouses, the pathogen can rapidly spread via splashing water. Disease development is favored by warm, moist conditions.
Infected transplants carry the pathogen into production fields.
In the field, widespread or severe symptoms generally do not develop unless the crop is sprinkler irrigated or subjected to a light frost during the production cycle. The pathogen survives in undecomposed celery residue. Disinfect transplant trays because bacteria may survive on dirty trays. In the greenhouse, lower the water pressure from overhead sprinklers because high pressures favor entry of the pathogen into celery leaves. In the field avoid sprinkler irrigation.