The threat of myrtle rust to New Zealand and how science is contributing to our preparedness. Beccy Ganley

The threat of myrtle rust to New Zealand and how science is contributing to our preparedness. Beccy Ganley

What is myrtle rust? Rust disease Austropuccinia psidii Can affect foliage, flowers and fruits Wide and expanding host range - over 445 known host species Wind-dispersed over long distances Spores can be transported on cars, clothing and personal effects Myrtle rust Acknowledge Angus Carnegie (NSW Department of Primary Industries) for photos Guava rust Eucalyptus rust Ohia rust

Cryptic symptoms

A. psidii across the Pacific 2005 2010 2013 Raoul Is. 2017

Climate suitability Variety of different models Modelled to Austropuccinia psidii species complex All predict suitability of areas in NZ Models have not been completed for the strain of A. psidii in the Pacific http://www.fs.fed.us/rm/pubs_other/rmrs_2012_hanna_j 001.pdf

Host susceptibility Infects in excess of 445 species in 73 genera worldwide. All myrtaceous genera considered potentially susceptible. Species vary in their susceptibility to different pathogen strains Evidence of variation in susceptibility within a species. Most susceptible hosts include: Agonis flexuosa (willow myrtle), Chamelaucium uncinatum (Geraldton wax), Decaspermum humile (silky myrtle), Eugenia reinwardtiana (Cedar Bay cherry), Gossia inophloia (thready-barked myrtle), Melaleuca quinquenervia (paper bark tea tree), Rhodamnia angustifolia, R. maideniana, R. rubescens (scrub turpentine), Rhodomyrtus psidioides (native guava) and Syzygium jambos (rose apple).

Risk to New Zealand natives Almost 30 native myrtaceous species Kunzea Leptospermum Lophomyrtus Metrosideros Neomyrtus Syzygium Several species known to be susceptible Degree of susceptibility unknown

Control of myrtle rust Prevent spread Destruction of infected material Chemical control Host resistance Unsprayed Sprayed

How science is contributing to our preparedness

Myrtaceae barcoding project MPI-funded; completed by Matt Buys and Beccy Ganley, Scion MPI recognised various difficulties with plant identification during an incursion: wide variety of Myrtaceae species in NZ difficult to distinguish some species lack of structures for identification number of plants to identify/extent of incursion

Barcode database of Myrtaceae in NZ 104 species of Myrtaceae covers the range of species in NZ includes species of economic and cultural importance Sequenced ITS, ETS and matk regions Rapid and accurate identification method only a small amount of plant material needed.

Host susceptibility expat plant survey Scion-B3 funded; completed by Peter Scott and Elizabeth Miller, Scion Expatriate survey of native NZ Myrtaceae planted throughout Australia to determine their susceptibility to Puccinia psidii and improve management Focused on Botanic Gardens, Private Gardens, Research Institutes and Nurseries in Brisbane, Sydney and Melbourne, Australia. NZ native Myrtaceae found to be susceptible to P. psidii included Metrosideros excelsa, M. kermadecensis, Lophomyrtus obcordata and L. x ralphii

Metrosideros kermadecensis, Sydney Lophomyrtus obcordata,victoria Lophomyrtus. x ralphii, Victoria

Host susceptibility Masters student Peter Scott, Beccy Ganley, Elizabeth Miller (Scion), Mike Wingfield, Jolanda Roux (FABI), Carlos Rodas (Colombia), Rebecca Stanley (Auckland Botanical Gardens), Amanda Black and Nick Waipara (Māori Biosecurity Network) Identifying myrtle rust resistance in key NZ Myrtaceae Determine susceptibility of 5 keystone Myrtaceae species to the two main Austropuccinia psidii (myrtle rust) isolates Pacific/Australian strain South African strain Capability development in biology, epidemiology and control of myrtle rust disease

Biosecurity networks interventions Biological Heritage National Science Challenge funded; Philip Hulme (LU), Daniel Stouffer (UoC), Beccy Ganley (Scion), Nick Waipara (AC), plus others Develop network models that link the potential for pest or pathogen spread through Nursery pathways Natural areas Models will allow stakeholders to identify opportunities for interventions to either contain or slow the rate of spread of unwanted pathogens, Provide new methods to safeguard New Zealand s native flora and ecosystems.

Future Research MBIE Catalyst Fund Proposal PFR (lead), Scion & Australian colleagues Host susceptibility Seed banking UAV surveillance Better Border Biosecurity (B3) meeting in May to identify biosecurity research priorities