California farms produce 93% of the celery grown in the United States. The crop thrives in coastal California’s moderate climate. Celery is an important crop in Ventura County with 40% of the state’s acreage farmed here. Valued at over $182 million, it was the second most profitable crop for Ventura County agricultural producers in 2010, which are the most recent statistics available.

Most celery in the field is planted as transplants. Transplants are typically grown under high humidity and high plant density conditions and are subject to seedborne pathogens. The most significant being Septoria apiicola (the causal agent of Septoria late blight) and Pseudomonas syringae pv. apii (the causal agent of bacterial blight). These diseases can be carried from the transplants into the field. As the plants mature, these diseases can cause plants to become unmarketable at a great loss to the growers.

UCCE’s Oleg Daugovish and collaborators researched these pathogens and how to best reduce disease and loss in the field. Over four years, the researchers documented that: seed, seedlings, weeds located in or near fields that harbor the virus can cause the disease in celery. This disease is likely transmitted by aphids, vectoring the virus.

The studies provided practices growers can use to manage this disease. Findings indicated that growers can control the pathogens by managing poison hemlock weed populations, controlling aphids, and planting celery cultivars that are not susceptible to the pathogens.

The interpretive and technical summaries of the research report can be viewed on this page of the USDA’s Agricultural Research Service. The full text can be accessed through the American Phytopathological Society, or at the UCCE office in Ventura County.

Poison hemlock, conium maculatum, located in or near fields harbor the virus can cause disease in celery. Photo by Joseph M. Ditomaso.