HONOLULU — Rapid Ohia Death has been found on Oahu.
The fungus, which attacks native ohia trees, was discovered on Hawaii Island in 2014 and spread to Kauai in late 2017. The first confirmed case was found on Maui in early 2019.
Now, the fungus has encompassed four of the Main Hawaiian Islands and the rapid response and surveying efforts ongoing on the other three islands have now spread to Oahu with the discovery of the tree disease.
There are fungal pathogens that cause Rapid Ohia Death (ROD). The less aggressive of the two was discovered for the first time on Oahu in a dead ohia tree on private land in a remote area in the Ko’olau Mountains above Pearl City.
On Kauai, Ceratocystis lukuohia, the more aggressive of the two fungi, was detected in three trees in December 2017 on state Department of Hawaiian Home Lands property behind Anahola Mountain.
Infected trees have also been found on the Moloa‘a State Forest Reserve, on privately-owned land in Halele‘a moku, and near the Lihue-Koloa Forest Reserve.
Since then, 11 more trees have tested positive for C. lukuohia and 15 have tested positive for the second type of pathogen-causing ROD, Ceratocystis huliohia.
All these trees are on the same DHHL property behind Anahola Mountain.
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, according to the Department of Land and Natural Resources.
After the ROD discovery was reported on Oahu, samples were taken and analyzed by the United States Department of Agriculture lab in Hilo. The lab confirmed the presence of Ceratocystis huliohia and triggered additional surveys to determine the extent of the disease.
The diseased tree was found on Kamehameha Schools land, and the landowner is working closely with agencies to coordinate testing and spread prevention, according to DLNR.
Researchers still don’t know how the fungus spreads between trees and between islands, but fungus spores can be transferred by people in the forest on their boots and tools and even on vehicles. Some suggest it could travel on the wind.
The public can help stop the spread by making sure vehicles boots and gear are cleaned off after going through ohia.
This is probably the same fungus the state in it’s infinite wisdom imported to kill the guava. As usual, and despite criticism of the program by many, the powers that be never considered the unintended consequences and muddled ahead. They now reap what they sowed.
RG DeSoto
“This is probably the same fungus the state in it’s infinite wisdom imported to kill the guava.”
Well that’s a rash – and incorrect – assumption. From The College of Tropical Agriculture and Human Resources, University of Manoa:
“The exact origins of the ROD-causing fungi are unknown, but we know that they are not native to Hawaiʻi. ROD is an exotic/introduced disease. There are several hypotheses for how these fungi originated: 1) a strain was brought in on a plant carrier that wasn’t showing symptoms of the disease, 2) a different strain was brought to Hawaiʻi and mutated or 3) two separate strains were brought to Hawaiʻi and recombined to create the strains that are killing ʻōhiʻa.”
The state did not release a fungus to kill plants in the guava family. Austropuccinia psidii is the pathogen you may be referring to, a disease that has mainly impacted rose apple, ohia seedlings, and recently, perhaps, java plum. It most likely arrived accidentally on imported plants in the same plant family as guava, and it spread even more quickly than Rapid Ohia Death, because it is wind-borne. Rapid Ohia Death is caused by two new Ceratocystis species, never before known to science, now named Ceratocysis lukuohia and C. huliohia. These are a different class of fungus, have different symptoms, and are clearly different diseases–specifically, they only affect ohia, and they affect the wood, while Austropuccinia shows up on the leaves. One final note, the tiny helper the state did import to control strawberry guava is a gall-forming insect, a little critter called a psyllid. It is not a fungus, and does not kill the tree. It just slows its growth and fruit production. Psyllids are very particular–they can only live in their special host tree. The strawberry guava psyllid will only live in strawberry guava. Fun fact: every variety of ohia lehua has its own native Hawaiian variety of psyllid that lives in its leaves!