(Honolulu) – An aerial survey of some 20,000 acres of forest on O‘ahu has resulted in the fourth detection of Rapid ʻŌhiʻa Death (ROD) in an ʻōhiʻa in the Moanalua Section of the Honolulu Watershed Forest Reserve above Tripler Army Medical Center.
“Fortunately,” explains State Protection Forester Rob Hauff of the DLNR Division of Forestry and Wildlife (DOFAW), this tree is infected with Ceratocystis huliohia, the less aggressive species of the fungus associated with ROD.” The tree was located using a helicopter-mounted camera system developed by the University of Hawai‘i-Hilo, Spatial Data Analysis and Visualization Lab (SDAV). The collected images were analyzed in partnership with staff from the O‘ahu Invasive Species Committee (OISC) and DOFAW, as part of an on-going effort to improve the ability of field personnel to spot potentially infected trees.
The previous detections of the same species on O‘ahu include single trees on Kamehameha Schools land in Waiawa, and on two private properties in Windward O‘ahu residential areas. Nathan Dube, the manager of the OISC said both of those trees were planted ʻōhiʻa. He said, “Both of these detections were from concerned landowners, who reported their dead or dying ʻōhiʻa to OISC. An OISC field team cut down the trees, dissected them, and sent samples to a lab in Hilo for positive confirmation and for research purposes.”
The aerial survey that picked up the tree in the Honolulu Watershed Forest Reserve, focused on the area adjacent to the earlier Waiawa detection. Surveyors identified about 40 additional trees from the images that need to be sampled for the disease, including ground-truthing. That process will take some time, as the area is rugged and difficult to reach. DOFAW and OISC crews, with the help from experts on Hawai’i Island, decided to remove the infected branch of the tree and monitor it monthly for further signs of disease. Crews used a sealant on the wound to prevent additional disease infection.
*Please report location of dead or dying ʻōhiʻa trees with dead leaves still attached on O‘ahu to OISC at: firstname.lastname@example.org (Photos are helpful)
Residents and visitors can help protect our remaining ʻōhiʻa forests with the following actions:
- Avoid injuring ʻōhiʻa. Open wounds on ʻōhiʻa are an entry point for disease spores. The disease can also spread from tree to tree on machetes or other tools.
- Don’t transport ʻōhiʻa inter-island.
- Don’t move ʻōhiʻa wood or vegetation, especially from areas known to have ROD.
- Clean your hiking boots/gear/tools. Scrub off all dirt and spray boot soles and tools with 70% rubbing alcohol, and wash your clothes in hot water and use a dryer to ensure the disease is not spread on boots and clothing.
- Wash your vehicle if driving near ʻōhiʻa forests. The disease can remain alive and infectious in soil, so wash all dirt off vehicles.
Rapid ʻŌhiʻa Death has now been detected on Hawai‘ Island, Maui, Kaua‘i and O‘ahu since the fungal disease was first discovered in 2014. To date, the more aggressive form of the disease has not been found on Maui or O‘ahu, and is extremely limited on Kaua‘i.