Myrtle rust (Austropuccinia psidii) is a serious fungal disease attacking plants of the Myrtaceae (Myrtle) family, including many important native New Zealand species. It was detected on mainland New Zealand in May 2017 and is now found across the North Island and some parts of the South Island.
The disease is intensifying in the New Zealand environment and is particularly severe in the Auckland region this year. It is still an unwanted organism in New Zealand.
Plant producers are encouraged to sign up to the Plant Production Biosecurity Scheme (PPBS) which has a specific module for myrtle rust management.
NZ Plant Producers are currently working with Dr. Rob Beresford (Plant & Food Research) and HortPlus to develop an online decision support tool for myrtle rust. The tool combines the myrtle rust climate model developed by Dr. Beresford with local weather station information to create a tool which will help plant producers and collection managers identify the best dates to apply preventative fungicides to prevent infection.
The following information, courtesy of Dr. Rob Beresford, may also be useful:
Different species of myrtle have different susceptibility to the fungus. Native species in the genus Lophomyrtus are particularly susceptible in New Zealand, and there have been increased reports this year about infections in swamp maire (Syzygium maire), as well as the exotic species Syzygium smithii (lily pilly or monkey apple).
As the incidence of myrtle rust increases and the inoculum builds up in the New Zealand environment, infections in moderately susceptible species such as pohutukawa (Metrosideros), manuka (Leptospermum) and kanuka (Kunzea) are likely to become more common.
A comprehensive list of susceptible species can be found at this link: https://www.myrtlerust.org.nz/assets/Uploads/Suseptible-MR-Species.pdf