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Poster: Biology & Disease Mgmt: Mycology


Origin and consequence of myrtle rust (Puccinia psidii) in the New Caledonian biodiversity hotspot.
S. JULIA (1), M. Laurent (2), C. Fabian (1) (1) Institut Agronomique Néo-Calédonien, New Caledonia; (2) CIRAD (Centre de coopération internationale en recherche agronomique pour le développement), New Caledonia

The myrtle rust disease, caused by the fungus Puccinia psidii, is considered as one of the main environmental threat to plants belonging to Myrtaceae family worldwide. In New Caledonia, a biodiversity hotspot renowned for its extraordinary botanical richness and endemicity, the fungus was first reported in 2013. The Myrtaceae, the principal target of P. psidii, holds a prominent position in the New Caledonian flora by being the most species-rich family. Taking into account the ecological importance of Myrtaceae in many ecosystems, it was agreed to establish a disease management approach to mitigate the spread and the potential long term impacts of the pathogen. In this perspective, it is essential to refine our understanding of the dynamics of the host-pathogen-environment interactions. In order to reach this goal, we have conducted field-based assessments of the host range and disease monitoring on several species in a semi-controlled environment during two years. A genotyping survey of the rust showed that a unique genotype has been established throughout the whole territory. To date, P.psidii was reported on at least 40 host species. The results showed a wide variation in responses to the disease within Myrtaceae and across different habitats, as previously showed in other locations where the rust occurs. Intraspecific variability was also observed among a range of susceptible species.