Tree scourge found in main area of Hawaii Volcanoes National Park

Several cases of rapid ohia death were confirmed in the main unit of Hawaii Volcanoes National Park, marking the first instances of the deadly fungal disease in one of the most visited locations on the island.

Since February, five cases of ROD were detected in the Kipuka Puaulu (Bird Park) area. Two cases were found near the intersection of Chain of Craters Road and Hilina Pali, near Ko‘oko‘olau Crater.

“It was a real shock,” said park spokeswoman Jessica Ferracane. “It definitely was not unexpected, but it came as a shock when we learned the results … that the testing did show that we have ROD.”

The national park previously found cases of rapid ohia death in its Kahuku Unit, which is located in southeast Ka‘u and receives a small fraction of the visitor traffic that the main unit does. To date, there have been 26 confirmed cases of ROD in Kahuku.

Park employees along with members of a statewide working group dedicated to addressing rapid ohia death began sampling ohia trees in 2015. These samples, taken after aerial surveying conducted by the state Department of Land and Natural Resources, uncovered the first Kahuku cases.

As of this week, the group has sampled 433 trees in both units of the park.

“Up until relatively recently, even though we were doing these parkwide surveys, we hadn’t found it outside of lower Kahuku,” said park ecologist David Benitez.

Rapid ohia death is caused by the Ceratocystis fungus. The fungus affects vascular systems within a tree, cutting off its nutrient flow. A tree can be infected well before it shows symptoms, but once symptoms — the most noticeable being browning of leaves — appear, the tree dies within weeks.

Since cases of ROD were first reported in Puna in 2010, more than 50,000 acres of ohia forest on the Big Island have been affected, although the disease has not yet spread to other islands. A state Department of Agriculture quarantine on transporting ohia from Hawaii Island has been in place since August 2015.

Ceratocystis species also cause plant diseases such as oak wilt. In Hawaii, Ceratocystis fimbriata was responsible for outbreaks of sweet potato black rot going back to the 1940s.

There are two Ceratocystis species that cause ROD, neither of which has been found anywhere else in the world. They were identified by researchers at the Pacific Basin Agricultural Research Center in Hilo, but have not been given names.

It’s not known how the fungi arrived on Hawaii Island, and researchers are still trying to understand how the disease spreads from tree to tree. Recent research efforts have focused on the frass particles that disperse when beetles burrow into the bark of a tree.

ROD also can get into trees through wounds, such as scraped bark or spots where branches were broken.

“We do know that there is a human component to how this fungus spreads,” Benitez said.

That makes raising awareness of rapid ohia death all the more important for park employees and volunteers. Last year, 1.8 million people visited the park (6,713 people visited Kahuku).

“We’re reallocating park staff to focus on this because it’s such an important (issue),” Benitez said. The sampling efforts continue to be a partnership with the working group.

“There’s no way that, strictly with park service personnel, we could have done that sampling,” Benitez said.

The park received $59,803 in National Park Service funds in 2016 for the purpose of ROD monitoring and management. This year, it received $45,731. The Department of the Interior also funded an early detection and rapid response program.

A new ROD information section was added to the national park’s home page so people can prepare before their visit.

Three community outreach programs are planned for the next two months.

Within the park, sanitation stations for parkgoers to clean their footwear are set up in heavily trafficked areas. The stations were already in place in locations such as the backcountry office.

“Our interpretive park rangers who are doing guided programs — they will sanitize and (clean) boots with alcohol,” Ferracane said. The same is true of volunteer projects.

Guided hikes such as “Explore the Summit” take place three to four times a day and take visitors through unaffected ohia forest. Rangers now incorporate rapid ohia death into their talks as they walk beneath the canopy.

People often are surprised to learn about ROD, Ferracane said, but are very supportive of the park’s efforts.

“They come from areas where tree disease has impacted their own communities, whether it’s oak wilt or Dutch elm disease,” she said.

Management of the confirmed cases in the park is determined on a tree-by-tree basis.

In Kahuku, trees were felled and covered with tarp to prevent disease spread. But Kipuka Puaulu is a more sensitive ecosystem containing rare and fragile species.

“Felling a large tree in those areas might not make the most sense,” Benitez said. “You also risk wounding other trees.”

The working group analyzed beetle colonization in the Kipuka Puaulu trees to determine the likelihood of ROD spreading and decided the best course of action would be continued monitoring.

Another tree near Chain of Craters Road was heavily colonized by a frass-producing beetle.

“It had more infections potential,” Benitez said. “So with that one we went and cut it down as soon as possible, and covered it with tarp. It’s case by case, and it’s definitely adaptive management.

“For me personally, and for the work group, we’re seeing this as a call to action. It’s something additional, part of our kuleana, to make sure that we are doing the best job possible to minimize this disease becoming more widespread.”

Ferracane said the new cases were a sobering reminder of a new reality: “We have to be vigilant in keeping this forest healthy.”

To learn more about rapid ohia death, visit www.rapidohiadeath.org or www.nps.gov/havo/learn/nature/rapid-ohia-death.htm.

Email Ivy Ashe at iashe@hawaiitribune-herald.com.