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SITUATION OVERVIEW The identification, pathology, distribution, and severity of Rapid 'Ohi'a Death—This new disease is caused by two spe- cies of the fungal pathogen Ceratocystis, which has rapidly spread across the southern districts of Hawai'i Island and killed millions of 'ohi'a trees (Metrosideros polymorpha). The disease currently impacts over 50,000 acres of 'ohi'a forest, representing about 10% of all 'ohi'a forest on Hawai'i Island. To infect a tree, the pathogen must enter through an open wound, after which It .',j, it spreads into the trunk, stopping water transport. Although p trees may be infected for many months before showing out- ward ut ward symptoms, once the first visible symptoms appear, death ' » follows within a few weeks, earning the name "Rapid 'Ohi'a ='F ' Death". Initial results from ongoing research into the impacts of the disease have shown average annual mortality rates as high as 20% in 'ohi'a forests where the disease is present, and nearly 100% mortality in areas where the disease has been present for An 'ohi'a tree may be infected several years. First detected in the Puna and South Hilo districts, for many months before showing ROD has spread to Ka'u and South Kona districts. There have symptoms, but once the pathogen been no confirmed cases of ROD in North Hilo, Hamakua, and moves into and blocks the flow of Kohala districts, nor have there been confirmed cases on any of water in the trunk, the tree crown the other Hawaiian Islands, as of November 2016. turns yellowish (chlorotic) and then brown within days to weeks, The 'ohi'a tree is Hawai'i's most important native tree species, with the entire tree dying soon occurring as the dominant tree in at least 80% of Hawai'i's na- after (J.B. Friday photo) tive forests and representing 50% of all forests in Hawai'i. Occu- pying nearly one million acres across the Hawaiian Islands, 'ohi'a forests extend from sea level to 8,000 feet in elevation and from very dry areas to rainforests receiving over 300 inches of rain per year. 'Ohi'a is often the first flowering plant to colonize fresh lava flows, and also flourishes on 4 million year old soils of Kaua'i. 'Ohi'a forests protect the upper reaches of the State's critically important watersheds, which supply fresh water to downstream communities and agriculture. The State's most endangered native birds such as the 'akepa and Hawai'i creeper make their home in high elevation 'ohi'a forests, along with hundreds of other native animals and plant species, many of which are rare, threatened, or critically endangered. Tens of thousands of Hawai'i Island residents live in or adjacent to 'ohi'a for- ests, and over a million people a year visit the 'ohi'a forests of Hawai'i Volcanoes National Park. 'Ohi'a forests have been treasured by native Hawaiians for centuries, not only for practical uses but also in art, such as hula where 'ohi'a is the kinolau (bodily manifestation) of important Hawaiian gods Ku, Laka, Kane, and Pele. Data gaps and knowledge voids —The origins and exact modes of entry into Hawai'i of the two Cer- atocystis species that kill 'ohi'a are currently unknown. DNA analyses of fungal samples from ROD-im- pacted trees do not match other Ceratocystis species catalogued in global databases. These two Cer- atocystis species are in the process of being taxonomically described and named as new species and are currently being referred to as Ceratocystis Species A and Ceratocystis Species B. Both Species A and Species B likely were accidentally introduced to Hawai'i with imported plants or plant parts — high-