Three different P. ramorum isolates, WSDA-1772, 5-C, both A2
mating type and clonal lineage NA1, and PRN-1 (CBS 101327), mating
type A1 and clonal lineage EU1, were cultured on 20% clarified
V8 agar. The V8 broth was first clarified by mixing 5 g of calcium
carbonate per 350 ml of V8-juice (Campbell Soup Co., Camden,
NJ), centrifuging at 4000 rpm for 20 min, and collecting the supernatant
(Mitchell and Kannwischer-Mitchell, 1992). The isolates
were maintained on autoclaved rye seed for long term storage