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More trees on Kauai afflicted with rapid ohia death disease

                                In a helicopter survey, state officials identified nine trees afflicted with rapid ohia death on Kauai.
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In a helicopter survey, state officials identified nine trees afflicted with rapid ohia death on Kauai.

State officials have found nine more trees on Kauai afflicted with rapid ohia death, the fungal blight that has decimated hundreds of thousands of native ohia trees in Hawaii.

Recent helicopter surveys detected signs of Ceratocystis lukuohia, the more deadly pathogen causing rapid ohia death, in upper Hanalei valley and the north side of Powerline Trail, according to the state Department of Land and Natural Resources.

“We’re disappointed to find C. lukuohia in nine ohia in these areas,” said Sheri S. Mann, Kauai district manager for DLNR Division of Forestry and Wildlife, in a news release. “But after extensive research into this new threat attacking ohia, we also know the fungal pathogens can move in the wind, by animals, and possibly by water too. So, unfortunately new detections aren’t as surprising as they are disappointing.”

The surveys also confirmed more rapid-ohia- death-positive trees in areas of the Garden Isle, where it was already known to exist.

Two different species of fungal pathogens result in the rapid killing of ohia trees — Ceratocystis huliohia and Ceratocysis lukuohia. The former may take months to years to kill ohia, while the latter can kill a tree within weeks.

Rapid ohia death was first detected on Kauai in the Moloaa Forest Reserve in May 2018. Since then, a total of about 86 trees have tested positive for C. lukuohia, while 74 have tested pos­itive for C. huliohia. One tree tested positive for both pathogens.

Another 161 trees were sampled but found to have neither pathogen following molecular testing.

“The hopeful news is that the disease has not been detected in the biodiverse-rich areas of Kauai such as Kokee State Park and the Alakai Plateau,” said Kyle Kagimoto, DOFAW’s Kauai invasive species technician in the release. “In these areas, ohia are critical to the preservation of our watershed and the needs of numerous endangered flora and fauna.”

A rapid response team, made up of state and federal agencies and non-government organizations, has been busy combating rapid ohia death with semi-annual helicopter surveys, intensified tree sampling, seedbanking and outreach activities.

Boot-brush stations have been installed at trailheads around the island. Drones have also been used to conduct forest plot surveys to track the expansion of the disease across the landscape.

The team has also partnered with the U.S. Geological Survey in research exploring the role of beetles in the spread of the disease.

Rapid ohia death was initially detected on Hawaii island in 2014, and limited to that island until state officials found the fungal blight on Kauai in 2018. It has since been found on Oahu and Maui, as well.

Symptoms of rapid ohia death include the sudden browning of leaves on limbs or the entire crowns of trees. The fungus is not visible on the leaves or bark, but grows in the sapwood just below the bark and impacts the tree’s vascular system, and, in turn, the flow of water.

DLNR reminds hikers, hunters and other recreationalists to take extra care while trekking through Hawaii’s forests with the following practices:

>> Avoid injuring ohia. Wounds (a broken limb, twig or exposed root or bark) serve as entry points for the fungus and increase the odds that the tree will become infected and die.

>> Clean gear and tools, including shoes and clothes, before and after entering the forest. Brush all soil off tools and gear, then spray with 70% rubbing alcohol. Wash clothes with hot water and soap and, if possible, dry on the high heat setting in the dryer.

>> Wash your vehicle with a high-pressure hose or washer if you’ve been off-roading or have picked up mud from driving.

>> Don’t move ohia wood or ohia parts, including adjacent soil.

>> If you see ohia with a limb or crown turning brown on Kauai, take a picture and send it to the Kauai Invasive Species Committee at saveohia@hawaii.edu or 821-1490. Describe exactly where you saw the afflicted tree.

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