Rapid ohia death found on Oahu for first time

Rapid ohia death, the fungal disease that has killed millions of ohia trees across Hawaii, has been detected for the first time on Oahu.

State officials said Wednesday that the disease was discovered on a dead ohia tree on Kamehameha Schools land in a remote area in the Koolau mountains above Pearl City.

The find triggered “a rapid response” effort that will include additional helicopter, drone and ground surveys to determine how widespread the disease is, according to the state Department of Land and Natural Resources.

“We’re taking this very seriously,” said Rob Hauff, state protection forester with DLNR’s Forestry and Wildlife Division.

Fortunately, he said, the find, confirmed by a U.S. Department of Agriculture lab in Hilo, represents the less aggressive of the two species associated with rapid ohia death.

Ceratocystis huliohia is known to take months to years to kill ohia trees, while the more aggressive species, Ceratocystis lukohia, can kill a tree within weeks and is responsible for wiping out 90% of the trees destroyed by rapid ohia death on the Big Island.

Oahu now becomes the fourth island where the disease has landed following its discovery on Hawaii island in 2014. To date, the more aggressive form of the disease has not been found on Maui or Oahu, and is limited on Kauai.

A partnership of state, federal, university and nongovernmental organizations has been conducting regular helicopter and ground surveys on Oahu to look for rapid ohia death since 2016. Some 150 dead or unhealthy ohia trees have been sampled for the disease in the past three years, and all have been negative until now, Hauff said.

The remote location of the infected tree means it is unlikely to have been spread by people, officials said, and researchers are still trying to understand the source of the two Ceratocystis pathogens and are looking at any possible patterns of dispersal.

On Oahu, ohia is found throughout the Koolau and Waianae mountain ranges across some 50,000 acres. The tree serves as a keystone species that helps with recharging island aquifers, providing habitat for endangered species and used for cultural purposes.

There is no known cure for either fungus. The fungal pathogens that infect ohia with rapid ohia death can be spread in soil that sticks to footwear, gear and tires.

To report dead or dying ohia on Oahu call or text the Oahu Invasive Species Committee at 286-4616 or e-mail oisc@hawaii.edu. Additional information can be found at rapidohiadeath.org.