Risk Background

Catharanthus roseus is one of the preferred hosts of the Candidatus Liberibacter species. Candidatus Liberibacter species are considered one of the most important pathogens of Citrus spp. Huanglongbing (HLB) caused by Candidatus Liberibacter species is a highly destructive disease of citrus. Australian territory is currently free from this disease.

Currently, the genus Candidatus Liberibacter is composed of three known species that cause disease, primarily in citrus: Candidatus Liberibacter asiaticus, Candidatus Liberibacter africanus and Candidatus Liberibacter americanus.

Seeds of infected Catharanthus roseus plants have been shown to carry Candidatus Liberibacter asiaticus. Importation of Catharanthus roseusseed therefore poses a serious risk of introducing bacteria into Australian territory.

HLB-like symptoms can be characterized with an initial vein yellowing that progressively expands into whole leaf yellowing. However, mild HLB-like symptoms can be characterized by a similar blotchy mottle on leaves and yellowing on of shoots.