Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2004
Publication Date: 9/4/2004
Citation: Bull, C.T., Goldman, P.H., Koike, S.T. 2004. Bacterial blight on arugula, a new disease caused by Pseudomonas syringae pv. alisalensis in California.Plant Disease. v. 88. p. 1384. Interpretive Summary: Arugula is an aromatic salad green that is high in Vitamin A and C whose popularity is increasing. Production in Monterey County California is highest during the warm summer months. Plant pathogens can limit the supply of arugula to the consumer and profits of the producers. The first step in reducing the impact of emerging plant diseases on crops is to identify the pathogen causing the disease. In this study we identified a novel disease of arugula that has been affecting this crop since 1995. The pathogen was previously misidentified as a related pathogen. The accurate identification is important because the correct pathogen has a broader range of plants on which it can cause disease than the misidentified pathogen. This information can be used by producers to make crop production choices that reduce the spread of the pathogen from one susceptible crop to another.
Technical Abstract: A novel bacterial blight of arugula Eruca sativa was seen for the first time in coastal California in 1995. Bacteria isolated from infected tissue were analyzed using standard biochemical and physiological tests including the standard LOPAT tests and fatty acid methyl ester analysis. Results from these tests were consistant with identification of the strains as Pseudomonas syringae. Additional analysis including rep-PCR and sensitivity to bacteriophage indicated that the organisms were P.s.pv alisalensis a newly emerging pathogen. Koch's postulates were completed by confirming pathogenicity on arugula and reisolation and characterization of the same organisms. Additionally, host range testing demonstrated that the arugula strains had a host range identical to that of P.s.pv. alisalensis. This first report of P.s.pv. alisalensis causing a disease on commercially grown arugula expands the host range of this pathogen.