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Natural Awakenings Hawaii

Rapid ʻŌhiʻa Death - How You Can Help

Aug 27, 2019 06:00AM ● By Beckie and Bud Kowalski

 ʻŌhiʻa trees are cherished and sacred beacons of Hawaiʻi. The existence of Rapid ʻŌhiʻa Death (ROD) has plagued the ʻŌhiʻa forests since 2014, when the first incidence was discovered on the Big Island. Since that time, hundreds of thousands of ʻōhiʻa have died from this disease. It’s called Rapid ʻŌhiʻa Death because healthy trees appear to die within a few days to a few weeks.

In May of 2018, the less virulent of the two fungal pathogens causing Rapid ʻŌhiʻa Death, Ceratocystis huliohia, was detected on Kauaʻi. In December 2018, Ceratocystis lukuohia, the more virulent fungal pathogen causing ROD, was also detected on Kauaʻi. Maui had an incident of the less virulent form in July of this year.

The only visual cue of infection is when a tree’s leaves suddenly turn brown and the tree begins to die. Detection methods are labor intensive, often including traversing rugged terrain to collect samples. There’s no clear way to identify trees that may have been exposed to the fungus when they are not showing signs of infection. Once the leaves turn brown, it’s too late to save the tree or prevent the spread of the disease.

Since 2016, systematic helicopter and ground surveys have been conducted by a partnership of state, federal, university, and non-governmental organizations. In the past three years, 150 dead or unhealthy ʻōhiʻa trees on Oʻahu have been sampled and all have been negative for ROD, until now.

Just recently a team of natural resource managers from the Oʻahu Invasive Species Committee (OISC) and the Koʻolau Mountain Watershed Partnership (KMWP) sampled a dead ʻōhiʻa tree on Kamehameha Schools’ land in a remote area of the Koʻolau Mountains above Pearl City. The sample was sent to the USDA Agriculture Research Service lab in Hilo where the presence of Ceratocystis huliohia was confirmed. Although this is the less aggressive of the two Ceratocystis pathogens associated with ROD, Oʻahu trees are still at risk.

This case of ROD on Oʻahu has initiated a rapid response that includes helicopter, UAS (drone) and ground surveys planned with OISC, DLNR and KMWP. Kamehameha Schools is working with the response agencies to coordinate access to the property to enable testing and prevent its spread.

ʻŌhiʻa grows throughout the Koʻolau and Waianae mountain ranges across approximately 50,000 acres. They provide important watershed cover to recharge the island’s aquifer, habitat for endangered species and cultural uses.

Our ʻōhiʻa forests need our protection. The following actions are necessary to safeguard these precious trees:

Avoid injuring ʻōhiʻa
Disease spores enter ʻōhiʻa through open wounds. The disease can also spread from tree to tree on machetes or other tools.
Don’t transport ʻōhiʻa inter-island
This includes ʻōhiʻa wood and vegetation, especially from areas known to have ROD.
Clean hiking boots/gear/tools
To avoid transporting spores, scrub off all dirt and spray boot soles and tools with 70% rubbing alcohol, and wash clothes in hot water and use a dryer.
Wash your vehicle if driving near ʻōhiʻa forests
Because the disease can remain alive and infectious in soil, wash all dirt off vehicles.

To report dead or dying ʻŌhiʻa on Oʻahu, please call or text the Oahu Invasive Species Committee at 808-286-4616 or e-mail [email protected] Additional information about Rapid ʻŌhiʻa Death can be found at RapidOhiaDeath.org.

A special thanks to Will Weaver with the Ko’olau Mountains Watershed Partnership for notifying us of these findings and for providing the accompanying photo.

 

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