Rapid ‘ohi‘a death in Hawai‘i

Authors: CANNON, PHIL - Us Forest Service (FS); FRIDAY, JAMES - University Of Hawaii; HARRINGTON, THOMAS - Iowa State University; Keith, Lisa; HUGHES, MARC - University Of Hawaii; HAUFF, ROB - Hawaii Department Of Land And Natural Resources; HUGHES, FLINT - Us Forest Service (FS); PERROY, RYAN - University Of Hawaii; ROY, KYLLE - Us Geological Survey (USGS); PECK, ROBERT - Us Geological Survey (USGS); SMITH, SHERI - Us Forest Service (FS); CORDELL, SUSAN - Us Forest Service (FS); LUIZ, BLAINE - Akaka Foundation For Tropical Forests; JUZWIK, JENNIFER - Us Forest Service (FS); YELENIK, STEPHANIE - Us Geological Survey (USGS)

Submitted to: Forest Pathology
Publication Type: Book / Chapter
Publication Acceptance Date: 4/27/2022
Publication Date: 7/1/2022
Citation: Cannon, P., Friday, J.B., Harrington, T.C., Keith, L.M., Hughes, M.A., Hauff, R., Hughes, F., Perroy, R., Roy, K., Peck, R., Smith, S., Cordell, S., Luiz, B., Juzwik, J., Yelenik, S. 2022. Rapid ‘ohi‘a death in Hawai‘i. Forest Pathology. 2:267-289. https://doi.org/10.1016/B978-0-323-85042-1.00013-6.
DOI: https://doi.org/10.1016/B978-0-323-85042-1.00013-6

Interpretive Summary: Rapid ‘Ohi‘a Death (ROD) is an extremely important pair of diseases as it has demonstrated a capacity to rapidly kill large numbers of the most important tree species in Hawai‘i and was unknown seven years ago. A significant amount of effort has been invested in learning about the etiology of the diseases. This book chapter covers many important topics, including ‘Ohi‘a, the pathogens, and the management and impacts of ROD.

Technical Abstract: Ceratocystis lukuohia and Ceratocystis huliohia are two newly recognized fungi that have arrived in Hawai‘i and are causing a serious vascular wilt and canker disease, respectively, of ‘ohi‘a trees (Metrosideros polymorpha), the most common and important tree species in Hawai‘i. Managing these diseases is presenting challenges because of some of the unique etiological aspects and the exceptionally pathogenic nature of one of these fungi (C. lukuohia) once it gains access to the tree’s vascular tissue. The role of ambrosia beetles and especially the frass they produce as a vector for the pathogen has required careful study, as well as the wounding of trees by many different agents which creates infection courts by which the pathogen can access and infect the vascular tissue. A range of control measures are being employed. These include a state-of-the-art monitoring program to detect diseased and recently killed trees and molecular biology approaches which can confirm if a given tree was infected by Ceratocystis. Based on monitoring it is estimated that over one million trees have been killed by the diseases to date. A major part of the program includes the deployment of a field crew which seeks out and treats large infected ‘ohi‘a trees as these trees are the main source of most of the infective Ceratocystis-laden frass. Long-term control measures also include fencing of some forests to reduce the amount of wounding to ‘ohi‘a trees by feral cattle and pigs and quarantine restrictions to ensure there will be no inter-island movement of the pathogens in ‘ohi‘a products. Finally, methods are also being developed to restore ‘ohi‘a forests affected by these diseases by determining effective regeneration practices and developing genetically-resistant ‘ohi‘a stock. Hawai‘i has an active extension program dedicated to providing information on how both residents and visitors can contribute to protecting ‘ohi‘a trees from these diseases. It is estimated that over 500,000 people have participated in this program. Hawai‘i residents have a very deep appreciation for this tree species and do what they can to help prevent these diseases from destroying more of their most treasured tree species.