1. Peter Scott – Forest Protection - peter.scott@scionresearch.com
Proactive Screening of Manuka (Leptospermum scoparium) for susceptibility to the biosecurity threat Myrtle rust (Puccinia psidii)
Peter Scott – Forest Protection -

2. All Myrtle rust (Puccinia psidii)
Guava rust
Ohia rust
Eucalyptus rust
All Myrtle rust (Puccinia psidii)

3. Myrtle Rust: Biololgy, Impacts, Dispersal
Puccinia psidii (Myrtle rust) was described (Guava) in Brazil in 1884.
In Brazil, in 1973, a major outbreak destroyed in excess of 400, 000 Eucalyptus seedlings and has caused major disease in over five million hectares.
Within Brazil, disease is managed with resistant clones using chemical controls.

4. Invasive pathogens, Novel host-pathogen association (Lack of co-evolution)
Chestnut blight (Cryphonectria parasitica): introduced into United States around 1900; spread rapidly and within 50 years had all but wiped out American chestnuts.
Dutch elm disease (Ophiostoma ulmi, O. novo-ulmi): a virulent strain arrives in Britain in mid-1960s and kills 25+ million trees; also devastating on mainland Europe and North America.
ctacf.org
kearneyhub.com
tsusinvasives.org

5. Myrtle rust is a Biosecurity threat because:
Wide host range
At least 340 Myrtaceous species, including 15 Leptospermum species other than Manuka, are known to be susceptible;
Significant impacts
Ranging from shoots and flower damage to defoliation, plant death and localized extinction;

6. Myrtle rust is a Biosecurity threat because:
Easily spread
The spores are aerially dispersed where they can spread many km within days; and
Spores may attach to clothing, equipment etc. and be spread thousands of km within hours.
Eucalyptus species
Guava

7. Global dispersal of Puccinia psidii

8. Myrtle rust is a Biosecurity threat because:
Climate modeling
Indicates that much of the North and some of the South Island is suitable for the disease

9. Identified native New Zealand species susceptible to Myrtle rust in Australia
Metrosideros excelsa
Metrosideros kermadecensis
Lophomyrtus obcordata
Lophomyrtus ’x’ ralphii

10. Metrosideros kermadecensis

11. Lophomyrtus obcordata

12. Lophomyrtus. x ralphii

13. However
The susceptibility of most species, including New Zealand Manuka, has not been determined. The potential impact on New Zealand’s Manuka honey industry is therefore unknown.

14. Project Proposal - Aim
Proactively help protect Manuka from Myrtle rust while it is not in New Zealand by:
Forming partnerships with Iwi, Maori groups and Landowners;
Determining the susceptibility of New Zealand Manuka to Myrtle Rust overseas; and
Identify resistance within the population which may be used for future revegetation and selective breeding.

15. Partnership
Source Manuka seeds for research, while respecting intellectual property rights and Matauranga Maori.
Record the location of trees so we can collect additional seed if required.

16. Screening
Some of the seed will be sent to an international research institutes. Seed will be germinated and tested for susceptibility to Myrtle rust.
Material sent to international institutes may be destroyed as required.
Screening for Myrtle rust susceptibility must be conducted internationally. Myrtle rusts should not be imported into New Zealand for research purpose.
Screening plants for susceptibility to Myrtle rust outside their natural range.

17. Direct industry benefits
This project can help identify resistant propagation lines for future plantings and breeding.
Genetic material from plants tested internationally may be further assessed to identify genetic markers of resistance, which can be used for future screening.
Thank you for your time
We would like to acknowledge and thank, Karen Te Kani; the proposed Manuka East Coast Iwi Coalition; Ngati Porou landowners, trusts and incorporations and Phil Caskey (NZ Manuka) for their hospitality and the opportunity to discuss this proposal.