Susceptibility of native New Zealand Myrtaceae to the South African strain of Austropuccinia psidii: A biosecurity threat

Austropuccinia psidii, the cause of myrtle rust, has spread globally where Myrtaceae occur. Multiple strains of A. psidii have been identified, including a unique strain found only in South Africa. Seedlings of four native New Zealand Myrtaceae species (Metrosideros excelsa, Leptospermum scoparium, Kunzea robusta, and Kunzea linearis) were artificially inoculated in South Africa with a single-uredinium isolate of the South African strain. Fourteen days after inoculation, uredinia, and in many cases telia, had developed on the young leaves and stems of all four host species, which led to shoot tip dieback in the more severe cases. Published in Plant Pathology.