HONOLULU — One of the species of fungus causing rapid ohia 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 Koolau Mountain Watershed Partnership (KMWP) recently sampled a dead ohia tree on private land in a remote area in the Koolau Mountains above Pearl City.
According to a press release by the Department of Land and Natural Resources, 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 ohia trees.
A partnership of state, federal, university, and non-government organizations have been conducting systematic helicopter and ground surveys to look for rapid ohia death since 2016. On Oahu, 150 dead or unhealthy ohia 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.
ROD threatens Hawaii’s most important tree species. Ohia grows throughout the Koolau and Waianae mountain ranges across approximately 50,000 acres. Ohia serves as a keystone species providing important watershed cover for recharging the island’s aquifer, habitat for endangered species, and cultural uses such as hula performances.