A stem canker disease of olive (Olea europaea) in New Zealand

A disease complex, with symptoms that include stem cankers and tip die-back , is reported in New Zealand olives (Olea europaea L.), Bacteria from stem cankers of olive were consistently isolated as pale lemon-yellow colonies o n King's medium B. On the basis of microbiological, molecular, and pathogen icity tests the bacterium isolated was identified as Xanthomonas sp. The ba cterial isolates allowed verification of Koch's postulates on young olive t rees. As a result of our findings we suggest that the stem canker on olive is caused by Xanthomonas sp. In addition a fungus identified as Fusicoccum luteum was consistently isolated from stem cankers and tip die-back. In ino culated plants F. luteum occasionally formed cankerous symptoms though not as aggressively as Xanthomonas sp. At this stage it is not clear what role F. luteum has in primary infection.