Cunningham (1956) first recorded poinsettia leaf spot in New Zealand but did not identify the pathogen, it was just mentioned as “taxonomic studies of leaf spot of poinsettia” in an annual report of the plant diseases division of DSIR. Dingley (1969) reported that that "Bacteria leaf spot on poinsettia is common in outdoor plants in late autumn in the Auckland area". She wrote that the disease was caused by Corynebacterium poinsettiae Starr & Pirone 1942 and cited Cunningham (1956) as the literature reference, however this was in error. Likewise, the publication by Brien & Dingley (1957) also makes this error. Hill (1979) in reporting Xanthomonas campestris pv. poinsetticola as a pathogen of Euphorbia pulcherrima in New Zealand examined the reports of diseases of poinsettia held by APHDS and in personal communication with ICMP curator and bacteriologist D.W. Dye concluded that “C. poinsettia is not known to occur in New Zealand at present”. As of Jan 2019 no cultures of this pathogen exist in the ICMP culture collection, the bacterial leaf spot disease of poinsettia is likely caused by another organism, such as Xanthomonas campestris pv. poinsetticola or Pseudomonas syringae. [BSW, Jan 2019].
References
Cunningham, G.H. 1956: PLANT DISEASES DIVISION. New Zealand Department of Scientific and Industrial Research. 30th annual Report., pp. 55-9
Brien, R.M.; Dingley, J.M. 1957: Third supplement to "A revised list of plant diseases recorded in New Zealand", 1955-1957. New Zealand Journal of Science and Technology. Section A: Agricultural Section 38(7): 777-782.
Dingley, J.M. 1969: Records of plant diseases in New Zealand. New Zealand Department of Scientific and Industrial Research, Bulletin. 192.
Hill, C.F. 1979: New plant disease records in New Zealand. New Zealand Journal of Agricultural Research 22: 641-645.

Isolated during export seed testing.