MOLOA‘A — Rapid ohi‘a death has found its way to Moloa‘a Forest Reserve on Kauai.
State Department of Land and Natural Resources botanist Adam Williams discovered five trees that looked like they were dead from symptoms associated with ROD while working in the reserve earlier this week.
By Wednesday, a team of state and federal officials, and people from university and non-governmental organizations had hiked into the area and started collecting data, taking photos and making observations.
Turns out, test results show it’s the less aggressive of the two fungi that are known to cause ROD on Hawaii Island.
“What were are finding on Kauai is a very different pathogen from the fungus killing large numbers of ohi‘a tress on Hawaii Island,” said Lisa Keith, lead researcher from the U.S. Department of Agriculture’s Agricultural Research Service.
She continued: “That fungus, Ceratocystis lukuohia (formerly called Ceratocystis species A), is a harsh tree killer and is very aggressive.”
The fungus on the Moloa‘a Reserve ohi‘a is Ceratocystis huliohia (species B). It’s also widespread on Hawaii Island, and its impacts are much less severe and slower moving.
“Both of them kill trees,” Keith said. “(Ceratocystis huliohia) spreads more slowly, but it still kills.”
Both types of fungus grow in the sapwood of an infected ohi‘a tree and it usually gets into the tree through a wound from breaking branches or root trampling.
Once it’s in the tree, it can take two or three years for the tree to die, and it affects stands haphazardly. Some stands, though, have shown a 90 percent mortality rate from contracting species A of the pathogen.
Experts say the pathogen doesn’t affect the other plants in Kauai’s forests.
As experts and officials respond to the fungus on Kauai through data collection on the ground and via drone and helicopter observations, they hope to learn more and identify the extent of the infection.
Jeremy Campbell, woodworker in Kalaheo and member of the Hawaii Forest Industry Association, said it’s discouraging to hear the fungus has spread, but at least it doesn’t affect the whole forest.
“It’s unfortunate that it’s affecting a native species, but there’s not a lot of uses for ohi‘a,” Campbell said. “There might be some cultural uses.”
The hard wood is sometimes used for making posts and beams, Campbell explained, but isn’t in very high demand.
“What I want to know is how it got here,” Campbell said.
Kauai Invasive Species Committee manager, Tiffani Keanini pointed out a silver lining for Kauai, saying not as many Kauai homeowners have ohi‘a trees in their yards, so there will be less need for sampling and testing in residential areas.
“We do expect to be involved in continued work to investigate and test for the potential spread of the disease in the forest of Kauai,” she said.
The fungus can be transported through mud on hikers’ shoes, via dust in the air, and insect activity.
While data collection and investigation continues, everyone involved will be keeping a sharp eye to discover the extent of the fungus on Kauai.
“The initial discovery of ROD has certainly made all of our people who work in the forest more aware of what to look for,” she said. “Without that increased awareness, we may have not found it on Kauai and failed to take the steps we’re now taking.”
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Jessica Else, environment reporter, can be reached at 245-0452 or jelse@thegardenisland.com.
