ʻŌhiʻa Disease Resistance Program

Establishing a Ceratocystis Disease Resistance Program for Metrosideros polymorpha

ʻŌhiʻa Disease Resistance Program

I ola ʻoe, i ola mākou nei

When you thrive, we all thrive.

We embrace this Native Hawaiian value and perspective of environmental kinship, and take from it that in caring for our ʻōhiʻa forests, we sustain the biocultural resiliency and integrity of our island communities, landscapes, and natural resources.

ʻōhiʻa seedlingmature ʻōhiʻa trees
Through collective stewardship of our biocultural landscapes we can support the current and future generations of ʻōhiʻa. (Photo: Kainana Francisco, Rebekah Ohara)

The Threat of Rapid ʻŌhiʻa Death and the Search for Rapid ʻŌhiʻa Death Resistance

ʻŌhi‘a (Metrosideros polymorpha) is the backbone of Hawaiʻi’s native forests and watersheds, covering nearly one million acres of land statewide, and is foundational to Native Hawaiian cultural practices and lifeways. Rapid ʻŌhi‘a Death (ROD), a phenomenon responsible for the death of hundreds of thousands of ʻōhiʻa trees across over 180,000 acres of Hawaiʻi’s native forests, is caused by two species of pathogenic fungi: Ceratocystis lukuohia and Ceratocystis huliohia. The ʻŌhi‘a Disease Resistance Program (ODRP) was established in 2018 to identify ROD-resistant ʻōhiʻa with the goal of producing disease-resistant plants for restoration of native forests, landscaping, and the perpetuation of ʻōhiʻa in our biocultural landscapes.

Ceratocystis lukuohia growing on a slice of carrot.
Ceratocystis lukuohia growing on a slice of carrot. The black, hair-like structures are spore-producing structures called perithecia. The orange disks at the tips of the perithecia are accumulated ascospores, a sexually-produced spore type. (Photo: Blaine Luiz)
inoculation with Ceratocystis lukuohia.
‘Ōhi‘a before (left) and after (right) inoculation with Ceratocystis lukuohia. (Photo: Blaine Luiz)
‘ōhi‘a forests where ROD is present
In ‘ōhi‘a forests where ROD is present, it is common to find dead and healthy ‘ōhi‘a trees existing next to each other. (Photo: JB Friday)

What Kind of Research is Needed to Support the Health of ‘Ōhi‘a?

ROD poses a significant threat to native ʻōhiʻa forests throughout the state, and critical research investments today include understanding how ROD spreads within and across sites, and how common ROD-resistant ʻōhiʻa are in our native forests. Here, we focus on the latter research need.

ʻōhiʻa plants in greenhouse
Developing methodology to accelerate the propagation time of ʻōhiʻa plants to a testable size is vital to our disease resistance work. (Photo: Blaine Luiz)
ʻŌhiʻa cuttings prepared with rooting hormone
‘Ōhi‘a cuttings prepared with a rooting hormone will eventually form roots and become a new plant. (Photo: Kainana Francisco)
ʻŌDRP field crew
Our field crews collect ‘ōhi‘a seeds and branch cuttings from sites with varying degrees of ROD in Hilo and Puna. Materials collected from the field are planted and the resulting plants are screened for ROD-resistance. (Photo: Kainana Francisco)
tiny ʻŌhiʻa seedlings
‘Ōhi‘a seedlings are incredibly tiny when they germinate. Seedlings will be ready for screening in about two years. (Photo: Kainana Francisco)

Our goal is to identify and make broadly available ROD-resistant ʻōhiʻa for restoration and landscaping applications across Hawai‘i. To achieve this goal, research is needed in the following areas:

  1. Improving ʻōhiʻa propagation methods to accelerate the time it takes to get large, healthy ʻōhiʻa.
  2. Developing disease screening techniques that are accurate and efficient.
  3. Propagating ‘ōhi‘ā survivor trees on Hawai‘i island from forests heavily impacted by ROD via cuttings and seeds, and inoculating resulting plants with the Ceratocystis pathogens to gauge resistance to ROD.
  4. Propagating Metrosideros taxa from ‘ōhi‘ā seed bank accessions, and screening resulting plants to assess statewide levels of ROD-resistance.
  5. Identifying the biochemical profile of ROD-resistant ‘ōhi‘ā, and developing remote sensing technologies to rapidly detect resistant ‘ōhi‘ā in the field.
  6. Establishment of a network of field sites to assess the roles that climate and environment play in disease resistance, and produce ROD-resistant seed.
  7. Identifying the mechanisms behind disease resistance, and, if more than one resistance mechanism is present, developing breeding protocols to create progeny with multiple forms of ROD-resistance.
  8. Developing molecular tools to rapidly screen offspring derived from controlled breedings.


ROD-resistant ʻŌhiʻa

As resistance to ROD is identified and cultivated, production of ROD-resistant ʻōhiʻa will be possible. ROD-resistant ʻōhiʻa will be widely available for restoration and landscaping, contributing to the perpetuation of ʻōhiʻa across Hawaiʻi.

ʻŌhi‘a that were inoculated with Ceratocystis lukuohia
‘Ōhi‘a that were inoculated with Ceratocystis lukuohia in 2016-2017 still alive over two years later. (Photo: Kainana Francisco)
ʻŌDRP greenhouse
ʻŌhiʻa rooted cuttings being grown for resistance screening. Plants will be ready for screening when they’ve reached at least 6 mm in stem diameter. (Photo: Chloe Martins-Keliʻihoʻomalu)

Supporting Our Communities

Critically, disease-resistant plants will provide our island communities with the opportunity to return ‘ōhi‘a to their backyards, schools, and places of work. The planting of native ‘ōhi‘a that are resistant to ROD, instead of non-native species, will allow these native plant communities to grow and foster an appreciation for native Hawaiian species. Providing communities with the opportunity to plant ‘ōhi‘ā without fear of ROD will foster a new generation of stewards that will care for the land and help support sustainable livelihoods for the areas in which they live.

Community Citizen Science for Hawaiian Forest Data -- Partnership with Pilina ʻĀina, formerly Teaching Change

To aid in the search for ROD-resistance, and provide a hands-on, impactful conservation experience, the ODRP is teaming up with Pilina ʻĀina, a partnership between the USDA Forest Service, Akaka Foundation for Tropical Forests, and University of Hawai‘i at Mānoa, and local schools to get students involved in ROD-resistance research.

As part of this program, ʻŌhiʻa Grow Kit packages, including locally collected seeds, will be given to students at two schools -- Laupāhoehoe Community Public Charter School and Kohala Middle School. Students will receive educational packets containing moʻolelo (stories) about ʻōhiʻa, as well as instructions on how to collect their own phenology data through kilo, or careful observation. As the students’ own ʻōhiʻa trees sprout and grow, they will track their progress and observe the trees through their early life phases. By the end of the project, students will potentially have two healthy ʻōhiʻa trees, one of which they can outplant into their own “backyard,” and one which can be donated back to the Institute of Pacific Islands Forestry’s greenhouse to support the disease resistance research, where each tree will be screened for ROD-resistance. Some of these trees may show ROD-resistance and be one of the genetic lines that helps to rebuild our native Hawaiian forests.

This project will be launched in the winter of 2021 at both Laupāhoehoe Community Public Charter School and Kohala Middle School. Each student will have their own sprouted seedlings in a few months, and the trees will be ready to outplant or transfer back for ROD research by the summer of 2022.

LCPCS students with the Ulu Lehulehu program learning about ʻōhiʻa phenology
LCPCS students with the Ulu Lehulehu program learning about ʻōhiʻa phenology at one of the ʻōhiʻa trees on their school campus. (Photo: Kainana Francisco)
LCPCS students and teachers  with the Ulu Lehulehu program
LCPCS students and teachers  with the Ulu Lehulehu program on a huakaʻi (trip) engaging with the landscapes of their district of Hilo. (Photo: Kainana Francisco)
students learning how to collect ʻōhiʻa seeds
LCPCS students with the Ulu Lehulehu program learning how to collect ʻōhiʻa seeds. (Photo: Kainana Francisco)

ROD-Resistance and Climate Change

As a keystone species, ‘ōhi‘ā forests provide food and habitat for numerous native insects, birds, and plants. Climate change is a major threat to the health of our native forests, and is predicted to destabilize the ranges of forest pathogens worldwide, resulting in further loss of our important native species. However, inclusion of ROD-resistant ‘ōhi‘a in forests mitigate the losses realized by ROD, leading to enhanced resilience of Hawaiʻi’s native forests and the species that inhabit them.

aerial view of an ʻōhiʻa forest
I ola ʻoe, i ola mākou nei - when we mālama and care for our ʻōhiʻa forests, our island communities, landscapes, and natural resources thrive! (Photo: Tyler Uehara)

For more information on ROD-resistant ʻōhiʻa and the ODRP, check out our program brochure, literature on our previous ROD-screening efforts, contact us at kokua@akakaforests.org, or call us at (808) 895-6991.

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Partnerships & Support

The Akaka Foundation for Tropical Forests is Proud to Work in Partnership with:

  • USDA Forest Service (Pacific Southwest Research Station - Institute of Pacific Islands Forestry, Region 5, Region 6)
  • USDA Agricultural Research Service (Pacific Basin Agricultural Research Center)
  • State of Hawaiʻi Division of Forestry and Wildlife
  • University of Hawaiʻi at Mānoa, College of Tropical Agriculture and Human Resources, Cooperative Extension
  • Purdue University
  • Tropical Hardwood Tree Improvement and Regeneration Center
  • Hawaiʻi Agriculture Research Center
  • Kalehua Seed Conservation Consulting
  • Arizona State University, Center for Global Discovery and Conservation Science
  • University of Hawai‘i at Hilo, Spatial Data Analysis and Visualization Lab

Financial Support Provided by:

  • The State of Hawaiʻi Division of Forestry and Wildlife
  • Hawaiʻi Community Foundation
  • USDA Forest Service