One of the species of fungus causing Rapid Ê»ÅŒhiÊ»a Death (ROD) was recently detected for the first time on Oahu. A team of natural resource managers from the Oahu Invasive Species Committee (OISC) and the Koâ€™olau Mountain Watershed Partnership (KMWP) recently sampled a dead Ê»ÅhiÊ»a tree on private land in a remote area in the KoÊ»olau Mountains above Pearl City.
The sample was analyzed by the USDA Agriculture Research Service lab in Hilo. It confirmed the presence of Ceratocystis huliohia. Although this is the less aggressive of the two Ceratocystis species associated with ROD, it still has the ability to kill Ê»ÅhiÊ»a trees.
A partnership of state, federal, university, and non-government organizations have been conducting systematic helicopter and ground surveys to look for Rapid Ê»ÅŒhiÊ»a Death since 2016.Â On Oahu, 150 dead or unhealthy Ê»ÅhiÊ»a trees have been sampled for the disease in the past three years, and all have been negative until now. The location of the infected tree is extremely remote and it is considered highly unlikely to have been spread by people. Researchers are still trying to understand the source of the two Ceratocystis pathogens and are looking at any possible patterns of dispersal.
This first detection on Oahu has initiated a rapid response which includes additional surveys to determine how widespread the disease is. A combination of helicopter, UAS (drone) and ground surveys are planned with OISC, DLNR and KMWP playing lead roles. The landowner, Kamehameha Schools, is working closely with the response agencies to coordinate access to the property so agencies are able to test for the fungus and prevent it from spreading.
Rapid Ê»ÅŒhiÊ»a Death threatens Hawaiiâ€™s most important tree species. Ê»ÅŒhiÊ»a grows throughout the Koâ€™olau and Waianae mountain ranges across approximately 50,000 acres. Ê»ÅŒhiÊ»a serves as a keystone species providing important watershed cover for recharging the islandâ€™s aquifer, habitat for endangered species, and cultural uses such as hula performances.
Residents and visitors can help protect our remaining Ê»ÅhiÊ»a forests with the following actions:
- Avoid injuring Ê»ÅhiÊ»a. Open wounds on Ê»ÅhiÊ»a are an entry point for disease spores. The disease can also spread from tree to tree on machetes or other tools.
- Donâ€™t transport Ê»ÅhiÊ»a inter-island.
- Donâ€™t move Ê»ÅhiÊ»a 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 vehicleÂ if driving near Ê»ÅhiÊ»a forests. The disease can remain alive and infectious in soil, so wash all dirt off vehicles.
Rapid Ê»ÅŒhiÊ»a Death has now been detected on Hawaii Island, Maui, Kauai, and OahuÂ 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 Oahu, and is extremely limited on Kauai.