ʻŌhiʻa Disease Resistance Program

Past ProjectsProjects

ʻŌhiʻa Disease Resistance Program

Project Collaborators

  • Kainana Francisco, Institute of Pacific Islands Forestry, USDA Forest Service
  • Christian P. Giardina, Institute of Pacific Islands Forestry, USDA Forest Service
  • Marc Hughes, Institute of Pacific Islands Forestry, USDA Forest Service
  • Rich Sniezko, Dorena Genetic Resource Center, USDA Forest Service
  • Phil Cannon, Pacific Southwest Station, USDA Forest Service
  • Nicklos Dudley, Hawai‘i Agriculture Research Center
  • Lisa Keith, Daniel K. Inouye Pacific Basin Agricultural Research Center, USDA Agricultural Research Service
  • James B. Friday, Department of Natural Resources and Environmental Management, University of Hawai‘i, Mānoa
  • Rob Hauff, Hawai‘i Division of Forestry and Wildlife
  • Douglass F. Jacobs, Department of Forestry and Natural Resources, Purdue University
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ʻŌhiʻa (Metrosideros polymorpha) covers over 850,000 acres across Hawaiʻi, is the backbone of Hawaiʻi’s native forests, and serves as a foundational species for Native Hawaiian cultural practice. Starting in 2010, ʻōhiʻa trees began dying on Hawaiʻi Island, undergoing rapid wilting and browning of the canopy. After intensive investigation, researchers identified the fungal cause of the new disease and named it Rapid ʻŌhiʻa Death (ROD). We now know that ROD is caused by two novel species of fungi, the highly virulent Ceratocystis lukuohia and the less aggressive Ceratocystis huliohia. It is estimated that over a million ʻōhiʻa trees have died due to ROD. Unfortunately, ROD was discovered on Kauaʻi in 2018, and Oʻahu and Maui in 2019.

While the widespread ʻōhiʻa mortality is troubling, there is evidence that some ʻōhiʻa genotypes on Hawaiʻi Island show resistance to ROD. During preliminary ʻōhiʻa screening trials, where ʻōhiʻa individuals were artificially inoculated with Ceratocystis lukuohia, we found that most individuals died within a few months. Critically, however, a handful of inoculated genotypes survived following inoculation; some have even survived a second round of inoculation. These results point to the promise of finding ʻōhiʻa and other Hawaiian Metrosideros species that are naturally resistant to ROD. To date, the extent of this resistance in natural populations is poorly understood. For this reason, we launched the ʻŌhiʻa Disease Resistance Program (ʻŌDRP), a multi-partner initiative of federal, state, and university entities, and led by the Akaka Foundation for Tropical Forests, to support the disease resistance needs of ʻōhiʻa, including identifying ROD-resistant plants vital to the restoration of forest areas impacted by ROD. Our goal is to support private landowners and conservation land managers who want to perpetuate ʻōhiʻa across their lands.

ʻŌhiʻa (Metrosideros polymorpha) plants from the first of the ʻŌDRP screening trials three months after being inoculated with Ceratocystis lukuohia, the most aggressive ROD pathogen (Photo credit: J.B. Friday).

In 2022, the ʻŌDRP

  • Hired two full-time positions to work closely with ʻŌDRP collaborators to support and expand the research efforts of the ʻŌDRP - Ryan Belcher as the ʻŌDRP Greenhouse & Operations Coordinator and Nainoa Goo as the ʻŌDRP Greenhouse & Field Specialist.
  • Concluded our first disease resistance screening trial, which ran for eight months from October 2021 through June 2022. The trial included 211 ʻōhiʻa trees from 56 genotypes collected from four areas of intense ROD-induced mortality in Hilo and Puna on Hawaiʻi Island. Plants were inoculated with Ceratocystis lukuohia, the most aggressive ROD pathogen. Data analysis is being conducted with US Forest Service Statistician, Nels Johnson.
  • Cared for over 450 plants (389 clones, 80 seedlings) designated for a second disease resistance screening trial. Plants were trimmed, fertilized, and moved to an outdoor growing area in the spring to boost growth, and then moved to the inoculation greenhouse at the Komohana Research and Extension Center in September to acclimate to the space before the inoculations. Greenhouse temperatures were still very high at the end of the year, so the inoculation trial was postponed to the new year until temperatures cooled.
  • Transplanted 2,500 rooted ʻōhiʻa seedlings to larger stock containers to grow to size for future inoculation trials, set to potentially occur in 2023.
  • Sowed seed in May for our Leilani Estates community science work in Puna and from our Maui partnership work in collaboration with Hawaiʻi Agriculture Research Center (HARC). Seed from an additional 33 families from our Hilo and Puna sites were sown in October. Seedlings propagated this season will be grown for two years, and are scheduled to enter inoculation trials in 2024.
  • Began a study looking at the length of time ʻōhiʻa plants are susceptible to ROD after a wounding event. ʻŌhiʻa plants were pruned and inoculated with Ceratocystis lukuohia, the most aggressive ROD pathogen, at various time intervals. The study will continue into the new year.
  • Began a study to investigate the susceptibility of other Metrosideros species and M. polymorpha varieties, that have yet to be naturally infected in the wild.
  • Continued to work with the ʻŌDRP advisory committee to finalize the design of a study that will look at growing media, pot styles and sizes, and irrigation methods to optimize growth of ʻōhiʻa plants for ʻŌDRP research.
  • Continued to work with the ʻŌDRP advisory committee to find ways to increase nursery production, including expanding growing space and switching to different pot styles and sizes, with the goal of growing 80 seed families (2,400- 3,200 individual plants) and testing 30-40 individuals per family during a single inoculation trial.
  • Conducted major upgrades and repairs at both the IPIF and Komohana greenhouse facilities, which included clearing out the entire Komohana greenhouse and installing weedmat, additional benches, and irrigation to increase inoculation bench space; reinforcing the structure of the Komohana greenhouse to prevent any potential theft of plants and equipment; repairing and making improvements to the IPIF greenhouse irrigation system; power washing the screens and polycarbonate walls and roof of the IPIF greenhouse to improve lighting and airflow for growing ʻōhiʻa; installing weedmat and irrigation and purchasing new tables for a new outdoor growing space at the IPIF greenhouse.

Additionally, the ʻŌDRP Community Science program continues to facilitate community science and biocultural education opportunities anchored in aloha for ʻōhiʻa.

Seedlings germinated for our community science work with Leilani Estates in Puna, Hawaiʻi (Photo credit: Kainana Francisco)
New ʻŌDRP staff members, ʻŌDRP Greenhouse & Operations Coordinator, Ryan Belcher (right), and ʻŌDRP Greenhouse & Field Specialist, Nainoa Goo (left), setting up ʻōhiʻa plants for the second disease resistance screening trial in the inoculation greenhouse at the Komohana Research and Extension Center. The inoculation trial was postponed to the new year until temperatures cooled (Photo credit: Kainana Francisco) 

In 2022, the ʻŌDRP Community Science program:

  • Partnered with the Pilina ʻĀina program and Laupāhoehoe Community Public Charter School (LCPCS) in the 2021-2022 school year to facilitate a community science and biocultural education program focused on empowering students in their roles as ʻāina stewards of their places. Working with 30 high school science students, we built pilina (relationship) with place through stories, history, huakaʻi (field trips), and established a community science research project studying the phenology of wild ʻōhiʻa trees on the school campus.
  • Partnered with Pilina ʻĀina, the Puʻuwaʻawaʻa Community Based Subsistence Forest Area program, and the Hawaiʻi State Division of Forestry and Wildlife (DOFAW) in the spring to host the Puʻuwaʻawaʻa Biocultural Blitz, an annual event for North Kona and South Kohala students to visit Puʻuwaʻawaʻa and learn about science and stewardship. This year, ʻŌDRP helped to create a brand new self-guided, outdoor activity called The ʻŌhiʻa Trail Challenge, which ran from April 22nd through May 1st. The activity involved participants hiking the ʻŌhiʻa Trail at Puʻuwaʻawaʻa, visiting seven QR code stations along the trail to watch short videos about the place and ʻōhiʻa, and practicing kilo or using their observation skills to complete a worksheet, which qualified them for a prize drawing.
  • Hosted outreach booths at the annual ʻŌhiʻa Love Festival on Hawaiʻi Island and Kauaʻi sharing information and resources on ʻōhiʻa, ROD, and the work and efforts of ʻŌDRP. For our Kauaʻi outreach booth, we also created an ʻōhiʻa phenology monitoring activity for that specific area, and provided 22 families with ʻōhiʻa grow kits (ʻōhiʻa seed from Kauaʻi, a planter pot, planting media, and an instructional handout on how to grow ʻōhiʻa).
  • Started drafting a new “how to” resource for our community science work focused on collecting and storing ʻōhiʻa seeds and growing ʻōhiʻa from seed at home.
  • Worked with Pilina ʻĀina to create a simplified ʻōhiʻa phenology monitoring sheet for Hawaiʻi kumu (teachers) to use in their Pilina Kaiāulu Program.
  • Inspired an LCPCS high school student, who participated in our community science and biocultural education program, to focus her senior legacy project on creating opportunities for others in her school to learn about the importance of native plants, like ʻōhiʻa, in our ecosystem. We will be mentoring this student for the 2022-2023 school year and providing her with support and guidance as she develops her project.
  • Continued to propagate and maintain ʻōhiʻa plants for our Laupāhoehoe and Leilani community science work and research.
ʻŌDRP Community Science Program Coordinator, Chloe Martins-Keliʻihoʻomalu, hosting an ʻŌDRP outreach booth at the ʻŌhiʻa Love Festival at Limahuli National Tropical Botanical Garden on Kauaʻi (Photo credit: Chloe Martins-Keliʻihoʻomalu)

Over the next year, we will continue to grow and screen ʻōhiʻa seedlings from across the state. We will continue to work with the ʻŌDRP advisory committee to optimize growth and production of ʻōhiʻa plants for ʻŌDRP research, and develop efficient inoculation methods with the goal of also improving the accuracy of our inoculation-based test. And, we will outplant potentially resistant individuals from initial 2016-2017 efforts and the first ʻŌDRP disease resistance screening trial, while initiating our field-testing phase, both of which will put us closer to identifying ʻōhiʻa resistant to C. lukuohia.

The severity of ROD poses a significant threat to native ʻōhiʻa forests throughout the state, and full investment into the strategies listed above will be critical for perpetuating ʻōhiʻa across Hawaiʻi. None of this work would be possible without financial support from the USDA Forest Service (Washington Office, Region 5, and Special Technology Development Program), the Hawaiʻi Community Foundation, and the Hawaiʻi Department of Land and Natural Resources, Division of Forestry and Wildlife. For more information, please visit Akaka Foundation for Tropical Forests’ website (www.akakaforests.org) where you can find a brochure about the ʻŌDRP, detailed information about our community outreach and engagement efforts, and ways to support the ʻŌDRP.