Rapid ʻŌhi‘a Death Fungus Discovered on Kaua‘i

ROD has affected more than 135,000 acres of ʻōhiʻa forests on Hawai‘i Island since it was identified more than four years ago. PC: Big Island Now.

Five ʻōhiʻa trees on Kaua‘i have been discovered dead as a result of Rapid ʻŌhiʻa Death (ROD) fungus. Kaua‘i DLNR Division of Forestry and Wildlife (DOFAW) botanist Adam Williams discovered the trees last week in the Moloa‘a Forest Reserve and lab results confirmed the presence of the fungus known as Ceratocystis huliohia (formerly called Ceratocystis “species B”).

In response, a team of experts from state and federal agencies and nonprofit organizations gathered to investigate the tree deaths using drone and helicopter flight surveys and lab tests.

On Wednesday, May 9, team members from the DLNR/DOFAW, Dr. Keith’s USDA lab, the University of Hawai’i’s College of Tropical Agriculture and Human Resources, the Kaua‘i Invasive Species Committee (KISC) and The Nature Conservancy (TNC) hiked into the forest reserve to examine the two trees confirmed to be infected.

“What we are finding on Kaua‘i is a very different pathogen from the fungus killing large numbers of ʻōhiʻa trees on Hawai‘i Island,” said Dr. Lisa Keith, lead researcher from the USDA Agricultural Research Service (ARS). “That fungus, Ceratocystis lukuohia (formerly called Ceratocystis “species A”), is a harsh tree killer and is very aggressive.”

“Unlike on the Big Island, not many Kaua‘i homeowners have ʻōhiʻa trees in their yards, so there should be much less need for us to do tests and sampling in residential areas,” said Tiffani Keanini, KISC project manager. “We do expect to be involved in continued work to investigate and test for the potential spread of the disease in the forests of Kaua‘i.”

Rob Hauff, state protection forester for DLNR/DOFAW emphasized several protocols to prevent the spread of ROD including scrubbing boots and other footwear with 70 percent isopropyl alcohol after forest visits and thoroughly washing any equipment and vehicles that enter forested areas.

“This should become a best practice statewide for all forest users, since we still don’t fully understand how these fungi move from place to place,” said Hauff. “What is clear is that both species, and for that matter many tree diseases, enter trees through wounds, so it’s important not to wound them.”

More than 135,000 acres of ʻōhiʻa forests on Hawai‘i Island have been affected by ROD since it was identified more than four years ago. The extent of the current infection on Kaua‘i is unknown, and there is no indication that it spread directly from Hawai‘i Island, according to researchers.