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Rapid ohia death, the fungal blight that has killed off hundreds of thousands of native ohia trees in Hawaii, has been detected once again on Oahu, according to state officials.
A single ohia tree — Oahu’s fifth — was found infected recently near the popular Poamoho trail above Wahiawa, according to the state Department of Land and Natural Resources.
Officials confirmed the tree was infected with Ceratocystis huliohia, the less aggressive of the two fungal species responsible for the blight. It has afflicted four other trees on Oahu and has been found on each of the four main islands.
An aerial survey in November found the isle’s fourth case of the fungal disease on Oahu at the Honolulu Watershed Forest Reserve above Tripler Army Medical Center.
Previously, it had also been detected on Kamehameha Schools land in a remote part of the Koolaus above Pearl City, as well as in two different residential areas of Windward Oahu.
“That’s kind of a large area, so that leads us to believe that it’s fairly widely distributed on the island,” said state protection forester Rob Hauff. “It’s not entirely surprising we’re seeing these isolated trees.”
Hauff said some scientists think C. huliohia may have been present in Hawaii longer than the more aggressive strain, Ceratocystis lukuohia, but that it was discovered while testing for the latter.
Both pathogens — which enter through wounds — shut down the ohia tree’s vascular system, causing its leaves to suddenly turn brown, affecting limbs and entire crowns. The difference between the two is how quickly they kill the trees. The more aggressive strain can kill a tree within weeks, while the less aggressive one takes months to years.
The more aggressive species has so far been detected only on Hawaii island and Kauai.
Nevertheless, Hauff said the state will be cautious in removing the latest infected tree, particularly since Poamoho is a critical watershed, home to numerous endangered plants and animals.
Crews will also sample the surrounding trees in Poamoho to ensure the fungus has not spread.
Rapid ohia death was first detected on Hawaii island in 2014, and had only been known to be present there for many years, but was found four years later on Kauai, then last year on Maui and Oahu.
The native ohia lehua tree, or Metrosideros polymorpha, is considered a cultural, keystone species, making up about 80% of Hawaii’s native forests, and vital to supporting native birds and insects.
To combat the spread of the disease, the state is seeking $20 million from this year through 2024 as part of its strategic response plan. Top priorities include the continuation of aerial surveys and disease diagnostics as well as ultimately finding effective treatment.
In the meantime Hauff reminds people entering forests anywhere in the state to practice clean hiking habits. That includes using the boot disinfecting stations available at some trailheads as well as cleaning equipment, vehicles and gear before entering a forest.
The public is also encouraged to continue reporting suspected cases of infection to their local invasive species committee.
REPORT AN AFFLICTED TREE
If you see an ohia tree whose entire crown or major limb has turned brown within a few days or weeks, please contact your local Invasive Species Committee:
>> Kauai: 821-1490 or kisc@hawaii.edu
>> Oahu: 266-7994 or oisc@hawaii.edu
>> Molokai: 553-5236, ext. 6585; or lbuchanan@tnc.org
>> Maui: 573-6472 or miscpr@hawaii.edu
>> Note: Please include a photo and description.
Source: College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa
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