Bacterial leaf spot of cilantro has gotten an early start in 2018 due to spring rains. As with all bacterial diseases of leafy green commodities, bacterial leaf spot of cilantro is completely dependent on free moisture from rain, heavy dew, or overhead sprinkler irrigation. Initial symptoms are water-soaked, angular shaped leaf spots that later become dark brown to almost black in color. In advanced cases the lesions have a greasy appearance and can spread throughout the planting, rendering the leaves unmarketable. The leaf spots are never round or oval and retain the angular, straight-sided shape. The pathogen is Pseudomonas syringae pv. coriandricola and is carried on the cilantro seed. This bacterium does not survive in the soil for long periods of time, so once a diseased cilantro crop is plowed into the soil and the leaves decompose, the pathogen will die. However, re-planting cilantro into a field with existing crop residue could result in re-infection from old diseased leaves. Bacteria present on an infected planting can be spread to adjacent cilantro by splashed or wind-driven rain and sprinkler water. This cilantro pathogen has also been found to infect parsley.
