A New Pathovar, Pseudomonas syringae pv. alisalensis pv. nov., Proposed for the Causal Agent of Bacterial Blight of Broccoli and Broccoli Raab.

The etiology of three foliar bacterial diseases of crucifers and the relationships between their causal agents were evaluated. Data from LOPAT, carbon utilization tests, and fatty acid analysis indicated that bacterial blights of broccoli and broccoli raab, and leaf spot of broccolini, were caused by strains of Pseudomonas syringae. Data from phage sensitivity, ice nucleation, single carbon source utilization, Polymerase chain reaction using BOXA1R primer (BOX-PCR), and host range analyses were identical for the pathogen causing leaf spot of broccolini and P. syringae pv. maculicola. The broccoli raab and broccoli pathogens infected broccoli raab, all crucifers tested, tomato, and three monocots (California brome, oat, and common timothy). None of the other pathogens tested (P. syringae pv. maculicola, P. syringae pv. tomato, or P. syringae pv. coronafaciens) caused disease on broccoli raab or on both crucifers and monocots. Data from phage sensitivity, ice nucleation, single carbon source utilization, BOX-PCR, and host range analyses were identical for the pathogens from broccoli raab and broccoli, but were different from other pathovars tested, and supported the hypothesis that a new pathovar of P. syringae pv. alisalensis pv. nov. caused a leaf blight on broccoli and broccoli raab.