‘Ohia flowers on the Big Island. Photo by J. B. Friday, University of Hawai‘i
What does a Big Island tree fungus have to do with Kaua‘i? A great deal, where the iconic native ‘ohia tree (Metrosideros polymorpha) is concerned. This endemic tree and the entire forest ecosystem it supports is under threat from rapid ‘ohia death, or ‘ohia wilt.
On the Big Island, numerous adult ‘ohia trees have died in the last two years from a recently discovered fungus called Ceratocystis. It has affected more than 6,000 acres from Kalapana to Hilo, with tree stands showing greater than 50 percent mortality.
The significance of the ‘ohia forest to the Hawaiian Islands cannot be overstated.
The Ceratocystis fungus produces radial stains in the sapwood of infected trees. This sample later was shown to have the disease. Photo by J. B. Friday, University of Hawai‘i
The tree is beloved for its lehua blossom and has many cultural uses, including construction of houses and canoes as well as use of the blossom in leis. The Hawaiian legend of ‘ohia and lehua, a story of two lovers who were changed by the Goddess Pele into tree and blossom is well known. It is the dominant tree in Hawai‘i’s native forests, comprising approximately 80 percent of forest stand.
“If we lose ‘ohia, we’ve lost the forest,” says scientist JB Friday, of the University of Hawai‘i College of Tropical Agriculture on the Big Island. This could mean the loss of habitat for native songbirds, watershed health, and the entire forest structure; so all efforts are being put towards controlling the disease’s spread.