Chasing myrtle rust in New Zealand: host range and distribution over the first year after invasion

After the detection of the myrtle rust pathogen, Austropuccinia psidii, in New Zealand, a biosecurity response was initiated, including a wide-spread surveillance programme. Through an intensive public awareness initiative, the general public was highly engaged in reporting myrtle rust infections and added significant value to the surveys by reporting first detections from most of the areas that are now known to be infected. During the first year of the response, Austropuccinia psidii was found in areas that were predicted to be at high infection risk in previous modelling studies. Significant surveillance resources were deployed to different parts of the country and the response surveillance team contributed to most of the new host species finds. Twenty -four species and six hybrids of Myrtaceae have been confirmed to be naturally infected by myrtle rust in New Zealand. Eleven of these are new host records globally and three were previously recorded only as experimental hosts.