ʻŌhiʻa Disease Resistance Program
Ulu Mau Loa ʻŌhiʻa Lehua
Perpetuating ʻŌhiʻa Lehua for Future Generations
Welcome to the ʻŌhiʻa Disease Resistance Program (‘ŌDRP). We are a collaborative between the Akaka Foundation for Tropical Forests and the USDA Forest Service Institute of Pacific Islands Forestry, located in Hilo, Hawai‘i. Our mission is to protect and restore Hawaiʻi's native forests by discovering, selecting for and developing ʻōhiʻa (Metrosideros polymorpha) plants that are naturally resistant to Rapid ʻŌhiʻa Death fungus, Ceratocystis lukuohia. These disease-resistant trees can be used to restore our critical watershed forests that have been devastated due to Rapid ʻŌhiʻa Death.
The primary objectives of the ʻŌhiʻa Disease Resistance Program are:
- To identify and develop ʻōhiʻa trees that are resistant to the Rapid ʻŌhiʻa Death fungus, Ceratocystis lukuohia.
- To develop eco-region specific orchards of ʻōhiʻa trees to produce the seeds needed for forest restoration and the public need.
- To perpetuate and restore ʻōhiʻa across Hawai‘i to preserve the ecology, culture, and communities dependent on this tree species.
- To educate the public and stakeholders about the importance of ʻōhiʻa trees, watershed forests and the threats they face.
The Importance of ʻŌhiʻa Trees to Hawaiʻi
ʻŌhiʻa is the most important tree in Hawaiian forests. These trees cover nearly one million acres across the islands and can grow in many different habitats, from sea level to high in the mountains. The scientific name "polymorpha" means "many forms," which can be seen in their different shapes (stubby shrubs to massive trees) and flower colors. ʻŌhi‘a trees are everywhere in our forests and are very important to our environment. Many threatened and endangered Hawaiian birds, insects, and other plants rely on ʻōhi‘a trees, making them important to Native Hawaiian culture. ʻŌhiʻa make up a major component of our watershed forests, which provide clean water for drinking, farming, and sustaining our way of life.
The Threat of Rapid ʻŌhiʻa Death
Rapid ʻŌhiʻa Death (ROD) is an umbrella term that describes two new diseases that both kill ʻōhiʻa and are caused by two newly discovered tree pathogens in the fungal genus Ceratocystis (C. lukuohia and C. huliohia). These fungi were unknown to the world of science until they started killing thousands of ʻōhiʻa trees across the Hilo and Puna districts of Hawaii Island since 2014. It is now estimated that Rapid ʻŌhiʻa Death has killed well over 1 million trees across the state, and it continues to spread. Each fungus can kill ʻōhiʻa by themselves, but of the two pathogens, Ceratocystis lukuohia is the most aggressive and causes a type of disease called a systemic vascular wilt. This wilt disease can stop ʻōhiʻa from uptaking and moving water from the roots and within the tree, leading to brown leaves, wilted canopies and eventually death.
Search for Disease Resistant Trees
The ʻŌhiʻa Disease Resistance Program was established in 2018 to identify ROD-resistant ʻōhiʻa for seed production, restoration of our native and watershed forests, conservation, and the perpetuation of ʻōhiʻa in our biocultural landscapes.
Research and Development
The cornerstone of the program is rigorous research to better understand how disease resistance in ʻōhiʻa is distributed across the landscape, how it works, and how best to grow and outplant ʻōhiʻa that can survive and thrive in the presence of Rapid ʻŌhiʻa Death. This work focuses on identifying trees that already show a natural genetic resistance—those with an inherited ability to withstand the disease. Our research is guided by the ʻŌDRP scientific research committee, which brings together many decades of experience in tree disease resistance breeding and implementation across a range of tree species throughout North America.
ʻŌhiʻa Disease Resistance Program Process
Locating and Collecting Seed from ʻŌhia Trees
In collaboration with our partners, we survey forests to identify and collect seeds from ʻōhiʻa trees from around the state. These collections are guided by various factors including partner needs, amount of ROD mortality in an area, geography and elevation, and ʻōhiʻa variety. We also work with Laukahi, the Hawaiian Plant Conservation Network, to coordinate the collection and screening of ʻōhiʻa seed families from partner seed banks across the state. Seeds from wild collections are then germinated and grown in our greenhouse facilities located at the US Forest Service Institute of Pacific Islands Forestry in Hilo, HI. This facility houses thousands of ʻōhiʻa plants from all over the state. Our staff are continuing to improve growing ʻōhiʻa and can take ʻōhiʻa from germinated seeds to inoculation-ready size in two years. ʻŌhiʻa is a slow-growing species, so reaching this stage in two years represents significant progress.
Disease Resistance Screening
In collaboration with our scientific leadership, including a plant pathologist, a geneticist, an ecologist, and a statistician from the US Forest Service, we have developed a greenhouse inoculation screening method, tailored to ʻōhiʻa, that provides us a robust and reliable method to determine natural levels of ROD resistance in our screened plants. These trials usually take 6 to 8 months. From these screening trials we have found dozens of potentially disease resistant ʻōhiʻa that could be used for future restoration. However, since these trees need to live 100+ years in the presence of ROD, field and forest evaluation trials are needed to confirm their long-term resistance.
Field Trials & Seed Orchards
Based on our greenhouse trials we can select mother trees that will produce seeds that grow into disease-resistant ʻōhiʻa plants. However, we do not know if these small disease-resistant plants can live in areas infested with ROD fungus (C. lukuohia) and still grow into healthy, large, seed-bearing trees. To test the durability of resistance, our best ʻōhiʻa selections will be outplanted in areas of intense ROD disease pressure to assess their survival and growth over time.
As we increase our collection of disease-resistant trees we will plant them into big ʻōhiʻa gardens to encourage them to cross-pollinate and produce seeds, this is called a “seed orchard”. By putting our best ʻōhiʻa selections together in a seed orchard, we can 1) preserve these important plant genetics for future generations, 2) potentially increase resistance levels by natural breeding and 3) create a seed source for disease-resistant ʻōhiʻa plants that can be used for planting and restoration.
Restoration
Our final goal is to establish eco-region specific seed orchards that can create disease-resistant ‘ōhi‘a specific to the area they were harvested. For example, planting seedlings from high elevation mother trees on high elevation sites. These outplantings will be the source for restoring heavily ROD impacted areas with the next generation of disease-resistant ‘ōhi‘a that can survive for generations to come, allowing our forests to reflourish with ‘ōhi‘a.
Research Team
Partnerships & Support
- USDA Forest Service (FS): Scientific leadership, research collaboration, greenhouse and lab support, and long-term program guidance.
- Hawaii Department of Land and Natural Resources DLNR – DOFAW Forest Health (Robert Haugh) : Financial support, state-wide strategic planning input, and assistance with outreach and statewide coordination.
- University of Hawaiʻi at Mānoa – Pacific Cooperative Studies Unit (Brian Tucker): Database development, GIS integration, and data management support.
- University of Hawaiʻi at Mānoa – NREM (JB Friday, Ph.D.): Greenhouse space for screening trials, financial support, and contributions to strategic planning and outreach.
- Purdue University (Douglass Jacobs): Research collaboration and technical expertise in tree improvement and forest restoration.
- USDA Center for Forest Genetics (Richard Sneizko, Ph.D.): Guidance on developing genetic resistance and long-term breeding strategies.
- USDA Mathematical Statistician (Nels Johnson, Ph.D.): Support for experimental design, statistical analysis, and supplemental trial evaluation.
- Hawaiʻi Agriculture Research Center (HARC): Collaboration on propagation, plant production, and applied research supporting large-scale screening and orchard development.
- Mauna Kea Watershed Alliance (MKWA): Partnership on seed collection, field trial siting, and long-term restoration planning across priority watershed areas.
- The Pua Foundation: Support for community engagement, program visibility, and capacity-building efforts that strengthen long-term stewardship.
- Tropical HTIRC (Hardwood Tree Improvement & Regeneration Center): Technical expertise in tree improvement, breeding strategies, and long-term orchard development.
- USDA ARS PBARC (Pacific Basin Agricultural Research Center): Past collaboration on pathology work, inoculation trials, and screening support that helped establish early program capacity.
- Laukahi: The Hawaiʻi Plant Conservation Network: Guides seed sourcing coordination and procurement.
- Maui Nui Botanical Gardens (MNBG): Collaborates on seed sourcing, seed banking, and materials from non-Hawaii Island seed collections.
Financial Support Provided by:
- The State of Hawaiʻi Division of Forestry and Wildlife
- The State of Hawaiʻi Department of Natural Resources
- USDA Forest Service, Pacific Southwest Research Station
- The Cooke Foundation
- Healy Foundation
- Hawaiʻi Community Foundation - The Steve and Gloria Gainsley Fund
Learn More & Get Involved
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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