California | University of California Cooperative Extension | West Region
UC Cooperative Extension research proactively addresses new diseases affecting California’s $18 million parsley crop, enabling growers to manage these problems, eliminate the use of unnecessary chemicals, and save money.
California in general and coastal counties in particular are well known for producing a wide range of specialty vegetable crops that contribute to agricultural diversity, including parsley. Many consumers think of parsley as an incidental garnish that merely adds color to a plate of prepared food. While indeed a garnish, parsley is widely used in dried spice mixes, soups and other prepared foods. Significant acreage in parsley is also dedicated to fresh-market uses in salads and other recipes. California produces almost 2,600 acres of this crop, with Monterey and Ventura counties accounting for 49 percent of the state’s parsley. California parsley is produced typically in high volumes and with high quality. However in the past few years, growers began to observe unfamiliar disease issues in their parsley fields. Leaf spots, blighted foliage and yellowed plants contributed to loss of quality and reduced yields. Because parsley growers do not have an industry research board to address such concerns, a formal and organized grant program was not available to address these issues.
Steven Koike and Oleg Daugovish, with UC Cooperative Extension in Monterey and Ventura counties, stepped in to initiate investigations into these new parsley problems. They collaborated with farmers and pest control advisers to understand the extent of the problems and to obtain samples of the diseased crops. The UC Cooperative Extension plant pathology diagnostic lab in Salinas was successful in isolating and identifying several pathogens that were responsible for causing the disease symptoms. Koike and Daugovish enlisted the help of USDA researchers in Salinas and Belstville, Md. for characterizing the discovered pathogens. They found that three new diseases were present in California parsley crops: bacterial leaf spot, Stemphylium leaf spot, and Apium virus Y disease. The team subsequently studied these three pathogens to determine the range of susceptible crops and the possible source of the pathogens. They also conducted field surveys and found that the three pathogens were present in several central and south coast counties.
Research on new parsley diseases sheds light on recent field problems Key research findings will enable growers to manage the problems. Two of the problems, bacterial leaf spot and Stemphylium leaf spot, are seedborne issues; this means that future management steps will include the use of pathogen-free seed. The Apium virus Y pathogen is found to be resident in weeds, so growers will need to remove poison hemlock and other weeds in the Apiaceae plant family. Previous to this research, some growers were spraying symptomatic fields because they believed that a disease called late blight was responsible. Based on UC Cooperative Extension findings, growers now know that late blight was not involved and that these applications are not useful for the new problems. Growers have ceased making these sprays, eliminating the use of unnecessary chemicals and saving costs. Projects such as this parsley disease investigation demonstrate the commitment that UC Cooperative Extension has for specialty and minor crops research. This research helped resolve a significant growing problem for this $18 million California crop.