The view from the air is startling: large stands of mature native ohia trees, dead or dying, their foliage turned from a vibrant green to a sickly yellow and brown.
Rapid ohia death, or ohia wilt, so far is spreading only on Hawaii island. But the unique dangers it poses likely will demand a more aggressive county, state and federal response. Officials should be ready and willing to do more.
The pathogen, a vascular wilt fungus known as ceratocystis, carries multiple threats.
First, it kills the large covering trees upon which a whole native forest ecosystem depends — from endangered birds and snails and low-growing native shrubs to the watershed itself — and raises the spectre of invasive species permanently replacing native forests.
Ohia also has unique significance in Hawaiian culture, as a sturdy wood for tools, medicinal uses for the leaves, and fiery red blossoms for hula.
Second, it is difficult to control, much less stop. Researchers believe the disease is transmitted through frass, a fine sawdust created by wood-boring beetles and carried by the wind through the forest. The spores enter through wounds in a tree and block the tree’s ability to transport water through its vascular system to its foliage. As a result, the diseased trees are scattered throughout the 600,000 acres of ohia forest on the island, at low and high elevations alike.
Third, it is spreading. Originally confined to areas of Puna and Hilo, it has been detected on the Kona side of the island.
Fears that rapid ohia death could be carried to other islands prompted the state Board of Agriculture on Tuesday to propose a permanent quarantine on transporting ohia plants and plant parts from Hawaii island, except under certain strict conditions.
The proposal, which will go to a public hearing, would make permanent an emergency order that was issued last August and is due to expire soon. Even so, a quarantine may not be enough: There are fears the wilt could spread to the as-yet-unaffected Hamakua Coast and be carried to Maui by a storm.
Fourth, there is no effective prevention or cure. While the pathogen can be killed in a lab, applying a fungicide at the required scale won’t work, experts say. And even if fungicide could work in backyards or in small isolated areas, the problem has grown beyond those measures.
Some sensible action has been taken. Besides the quarantine imposed by the Board of Agriculture, the Legislature passed House Bill 2675, which would appropriate $300,000 for research into rapid ohia death, in hopes of finding better tools to combat the disease.
Gov. David Ige should sign the bill. Too much is unknown about the pathogen, which appears to be spreading faster than the ability to contain it.
Members of the state’s congressional delegation have petitioned the federal government for help, urging Sally Jewell, the secretary of the Department of Interior, to devote more resources and personnel from the National Park Service and Fish and Wildlife Service to the task. Aside from the obvious state and local interest, ohia forests are a prominent feature in Hawaii’s national parks.
Researchers are trying to contain the problem as best they can, studying possible transmission routes and experimenting with ways to stop the spread, including cutting down dead trees in hopes of reducing the airborne spread of the spores.
Meanwhile, state and federal officials have launched a public awareness campaign to encourage people to tread carefully through ohia forests. The fungus can be carried on boots, clothes, vehicle tires and tools. Such measures as avoiding stands of dead ohia, washing vehicles, and cleaning tools and clothes with a disinfectant solution can help.
It’s critical to continue — and expand as required — these multipronged efforts to attack rapid ohia death, before it’s too late.
