A fungus that causes rapid ohia death has been detected on Kauai.
State officials said Friday that Ceratocystis huliohia, one of two pathogens that causes ROD, was detected this past week in at least five dead trees in the Moloa‘a Forest Reserve in northeast Kauai. It’s the first detection of an ROD pathogen outside of Hawaii Island.
Researchers aren’t sure if it was transmitted to Kauai from the Big Island, or if it has unknowingly been present for some time in the remote forest reserve.
The trees were tested after showing symptoms associated with the plant disease.
Ceratocystis huliohia is slow-growing and less virulent of two strains known to cause ROD on Hawaii Island. The other, Ceratocystis lukuohia, has been responsible for the vast majority of ROD-associated ohia tree deaths.
“They both kill ohia trees, but Ceratocystis lukuohia is the one causing widespread mortality on the Big Island,” said J.B. Friday, extension forester with the University of Hawaii.
“We’re sure it arrived here and mutated here very recently,” he said. “(Ceratocystis huliohia) we don’t know how long it’s been here. It may have been on Kauai for years, but we just never found it, or it may have been brought over to Kauai recently. … We do know it’s present on Kauai.”
Friday said researchers next will look at figuring out how widespread the fungus is on Kauai and genotyping it to see “if it’s exactly the same as that on the Big Island or a little bit different.”
“If it’s been humming along for decades on both islands, there would be small differences you can see,” Friday said.
ROD has been found in 135,000 acres of native forests on Hawaii Island, though in most areas affected, tree mortality is fewer than 5 percent.
Friday said ROD largely is “filling in areas where it’s already present” on Hawaii Island, and “we’re not seeing a bunch of spread to new areas.”
ROD was detected in North Kohala for the first time last year. The discovery prompted worry it could spread by wind-borne fungus to other parts of the state, particularly Maui, which is only 40 miles from that detection site.
“The quarantine for the Big Island is still in effect,” Friday said. “Especially since the more virulent fungus still is on the Big Island. This (detection on Kauai) is a serious concern, but it’s not a disaster, and no one is throwing in the towel. We’re still charging forward.”
Email Kirsten Johnson at kjohnson@
hawaiitribune-herald.com.
