Ohiʻa lehua is a flowering evergreen tree and are one of the few trees that’s endemic to Hawaii. But Ohia trees on the Big Island are facing a mysterious threat: Rapid Ohia Death (ROD). On Dec. 23, 2015, the Department of Land and Natural Resources (DLNR) put out a news release saying that “hundreds of thousands of Ohia trees” have been killed by “a fungus called Ceratocystis fimbriata.” Ohia trees are staples to the native forests of Hawaii and are key in watershed function.
The release describes the fungus as a disease that’s new and has never before seen affecting Ohia. “While apparently only impacting Big Island forests currently, this has the potential of spreading statewide, so it’s critically important we do everything to stop it,” said DLNR Chair Suzanne Case.
According to the DLNR, the fungus kills ohia trees quickly. Some landowners have seen symptoms of the fungus and in only a matter of weeks the tree is dead. The DLNR has mapped 38,000 acres of ohia that have recently died on Big Island as of May 10, 2016.
Unfortunately, an ohia tree that has been infected by the fungus can appear to be healthy for as long as a year before showing symptoms, such as browning of the leaves and branches. From that point, death can come in as little as a few days to a few weeks.
In late August 2015, the Hawaii Board of Agriculture (HBOA) placed a year-long quarantine on ohia. As the fungus continues to destroy ohia and no cause has yet been found, it’s expected that the quarantine will soon be made permanent. This quarantine includes ohia plants, plant parts, wood, frass (beetle sawdust) and soil, none of which can be transferred from Hawaii Island to the neighbor islands. There is currently no treatment for infected ohia or plant parts.
If ROD were to reach Maui, “an estimated 80 thousand acres of ohia dominated wet forest remaining on Maui, which makes up the majority of the remaining native forest on the island” would be at risk. That’s according to Charles Chimera, Weed Risk Assessment Specialist from Pacific Cooperative Studies Unit, University of Hawaii.
Chimera also said that the areas of Maui most likely be affected would “be in windward areas above about 3,000 feet on both East and West Maui. These areas are also prime watershed forest, so the loss of ohia would affect everyone if it results in a reduction in the island’s future water supply.”
The UH College of Tropical Agriculture and Human Resources provided a briefing for Gov. David Ige on May 10. They told him that “work has begun on identification of insects that may be vectors, and wood-boring beetles like bark beetles and ambrosia beetles that are highly likely to be incidental vectors”
In May of this year, U.S. Senator Brian Schatz, D–Hawaii, has also called for immediate action from Interior Secretary Sally Jewell.
“If this was a forest fire, there would be no question about an all-hands-on-deck, no-holds-barred response,” Schatz told Jewell. “Rapid Ohia Death is bigger than a forest fire in size and scope, and we need to treat it as such.”
Schatz has also rallied the Senate to pass a bill for the fiscal year 2017, which includes a provision to direct the U.S. Department of Agriculture (USDA) to “study reported recent outbreaks of Rapid Ohia Death in Hawai‘i and report recommended action for response and management within 90 days.”
Currently, there is no effective treatment to protect ohia trees from becoming infected. Authorities have only recommended that landowners should not move ohia, ohia parts or the soil around ohia. Tools used to cut or trim affected ohia should be rinsed with a 70 percent alcohol solution. Shoes and vehicles need to be washed of all soil and tree parts before entering an area of non-affected ohia.
“Agencies including the Maui Invasive Species Committee, East Maui Watershed Partnership, West Maui Watershed Partnership, Leeward Haleakala Watershed Restoration Partnership, Nature Conservancy, Haleakala National Park, US Fish & Wildlife Service, Hawaii DLNR, HDOA, Maui Forest Bird Recovery Project, Puu Kukui Watershed Preserve, UH CTAHR and others have joined together to prevent ROD from getting to Maui and are preparing to deal with and contain its spread if it does get here,” Chimera said.
For more information on Rapid Ohia Death, visit Rapidohiadeath.org.