Rapid ʻŌhiʻa Death Continues Across Big Island Native Forests

Several aerial surveys across six Hawaiian Islands revealed that the fungal disease known as Rapid ʻŌhiʻa Death has impacted nearly 50,000 acres of native forest on the Big Island.

That’s an increase of some 13,000 acres from surveys done earlier in 2016.

“It’s important to note that the aerial surveys still need verification by conducting ground-truthing and lab tests,” said Philipp Lahaela Walter, State Resource & Survey forester for the DLNR Division of Forestry and Wildlife.

A view from a helicopter of the Rapid ʻŌhiʻa Death Statewide Survey Results. The disease has impacted nearly 50,000 acres of native forest on the Big Island alone.

While some of the increase is due to expanding the survey area, much of it is due to new tree mortality.

Lahaela Walter and his team flew helicopters over vast tracts of forest on Hawai‘i Island, O‘ahu, Maui, Moloka‘i, Kaua‘i, and Lānaʻi, crisscrossing the landscape to look for tell-tale signs of the disease.

Rapid ʻŌhiʻa Death, first described by scientists as a previously unknown fungus in 2014, kills trees indiscriminately and often quickly.

“While we believe, based on the aerial survey work, that the disease continues to destroy hundreds of thousands of native ‘Ōhiʻa lehua on the Big Island, we saw scant evidence that the fungus is killing trees on the other islands,”added Walter. “We did spot trees that could be dying of other causes, but so far none of the samples has been positive for the fungus (Cereatocystis) that causes Rapid ʻŌhiʻa Death. Again we need to conduct ground surveys and either confirm or discount the presence of the disease in laboratory tests.”

On the Big Island, just over 47,000 acres—about 9%—of the forest surveyed showed symptoms of Rapid ʻŌhiʻa Death with brown or no leaves.

“The quarantine measures put into place by the Hawai‘i Department of Agriculture appear to be stopping its spread to other islands,” according to DOFAW’s Rob Hauff. “These rules require inspections of soil and plant materials and prohibit, except by permit, interisland movement of any part of a native ‘Ōhiʻa tree.”

Highly valued for their beauty and significance in Hawaiian culture, native ‘Ōhiʻa lehua forests cover approximately 865,000 acres of land across the state and are considered the primary species providing habitat for countless plants, animals and invertebrates.

These forests protect watersheds that provide significant agriculture and drinking water across the state. Rapid ʻŌhiʻa Death threatens the State’s tropical forests and delicate ecosystems and ultimately could jeopardize local water supplies and Hawaiʻi’s economic vitality.

The University of Hawai‘i Cooperative Extension Service and the USDA Agricultural Research Service assisted with planning for the helicopter surveys using specialized equipment.

A team of experts from DLNR/DOFAW, the U.S. Department of Agriculture Forest Service, Hawaii’s Invasive Species Committees, and the National Park Service/Hawai‘i Volcanoes National Park conducted the surveys.

Research into treatments for the particular fungus that causes Rapid ‘Ōhiʻa Death continues at the USDA Agricultural Research Service lab in Hilo.

Investigation into how it spreads is also being conducted with potential culprits being: insects, underground via roots, on small wood or dust particles, on shoes and equipment, and possibly on animals.

Ultimately, scientists hope to identify what is spreading the fungus and then be able to mitigate its impacts.

In announcing additional funding for the fight against Rapid ‘Ōhiʻa Death, Hawai‘i U.S. Senator Brian Schatz said, “This is an ecological emergency, and it requires everyone working together to save Hawai‘i Island’s native forests. I’m pleased to see our federal partners step up to help. The additional funding will make a big difference, and it will give us the tools to understand the disease, develop better management responses, and protect our ‘Ōhiʻa.”

For more information regarding Rapid ‘Ōhiʻa Death, click here.