Kaua`i `ohi`a infected most deadly form of Rapid `Ohi`a Death fungus

Dead `ohi`a in Kauai forest. Credit: DLNR photo.

The "mother of the forest" on Kaua`i is under deadly attack.

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The most aggressive form of Rapid `Ohi`a Death fungus has been identified in a stand of native forest on the island's east side, just months after the less aggressive type was found on the island.

The latest form is a fast-killing disease to which few or no `ohi`a are resistant.

`Ohi`a is perhaps the most significant tree of the Hawaiian forest—the canopy tree in many areas, and a nesting site for many birds. Its attractive red flowers are a major food source for Hawaiian forest birds, and its leaves and flowers are significant in Hawaiian culture.

Photos, a press release and other information are available at the website of the state Department of Land and Natural Resources, which announced the finding. 

Here is the press release:

(Lihue)-Detection of Ceratocystis lukuohia, the more virulent of the two fungal pathogens causing Rapid ʻŌhi‘a Death (ROD), has now been confirmed in three trees on Department of Hawaiian Home lands parcel behind Kalalea Mountain on the east side of Kaua‘i. This first detection of C. lukuohia comes after the other pathogen resulting in ROD, Ceratocystis huliohia, was detected on Kauai in three distinct locations this past year.

“These three trees that tested positive for C. lukuohia were spotted by our rapid response team as they were conducting botanical surveys across the island,” said Sheri S. Mann, Kaua‘i District Manager for the DLNR Division of Forestry and Wildlife (DOFAW). “Later, a team trekked by foot to visually inspect and take samples from the tree.”

ʻŌhi‘a die for many reasons, although symptoms consistent with ROD include the sudden browning of leaves on limbs or the entire crowns of trees. The fungus is not visible on the leaves or the bark but grows in the sapwood just below the bark. The three trees that were sampled earlier this month stood out in a forest of green, because the entirety of the trees leaves had browned.

Samples were then sent to the USDA Agricultural Research Service (ARS) in Hilo for the necessary laboratory testing that confirmed C. lukuohia in all three trees.

“This is obviously news we didn’t want to hear,” Mann said. “But within a day of learning the news, we scheduled a helicopter to conduct more digital mobile sketch mapping to identify any additional symptomatic trees. We followed that with pinpoint drone surveys conducted by the UH Hilo Department of Geography SDAV Lab and more tree sampling to try and determine the severity and distribution of the outbreak. It’s been a busy week.”

A benefit for Kaua‘i is the hard-earned research conducted on Hawaii Island where ROD was identified more than four years ago. Hundreds of thousands of trees have died due to ROD on Hawai‘i Island, more than 90 percent due to C. lukuohia. Earlier this year, scientists at ARS described the two-different species of fungi that cause ROD as C. huliohia and C. lukuohia. Both species are new to science.

The difference between the two pathogens is how they move through the tree and how quickly they kill.

“The pathogen enters the tree through a wound; be it a broken limb, twig or, perhaps, a scuffed up exposed root. Whereas C. huliohia may take months to years to kill an ʻōhiʻa tree, C. lukuohia can kill a tree within weeks,” said James B. Friday, the extension forester with the University of Hawaii.

The Kaua‘i ROD Working Group does not know exactly when or how the disease arrived on Kaua‘i-whether it was the result of human activity or on its own, e.g. via the wind.

Once additional lab results and drone imagery are available, the rapid response team will consult with the ROD science team to determine what management actions should be taken. 

“Our priority is to save ʻōhiʻa. It has a critical role in the ecosystem’s function,” said Tiffani Keanini, project manager of Kaua‘i Invasive Species Committee (KISC). “We are currently determining the best method to contain the spread and prevent ROD from entering pristine watershed areas. At this point, we are treating the recent outbreak with rapid response actions.  As we learn more about the distribution and density of the affected area, we will likely adapt our management strategy efforts.”

The C. lukuohia detection site is located in a remote area at 550-foot elevation. This forest location is comprised of a mix of native trees and plants like ʻōhi‘a, koa, hala, and uluhe that are being crowded out by non-natives such as albizia, java plum, strawberry guava, and octopus trees. Unfortunately, any loss of a native tree will give rise to the faster-growing invasives unless aggressive native tree plantings take place.

“The Department of Hawaiian home lands supports the DLNR efforts to save the ʻōhiʻa on Kaua’i and we thank their team for their swift action to date. We will continue to monitor the situation and do all we can to assist. We encourage our beneficiaries and the public to follow the distributed guidelines to prevent more trees from becoming infected,” said Jobie Masagatani, Chairman of the Hawaiian Homes Commission.

As there is no known cure to ROD, prevention is the key to ensuring it doesn’t spread and both Kama‘aina and visitors can help by following these key five guidelines:

1) Keep your eyes open. If you see ʻōhiʻa with a limb or crown turning brown, take a picture, and contact KISC via email (saveohia@hawaii.edu) or phone (808-821-1490). Samples of the wood must be taken by trained technicians and tested in a laboratory to confirm the presence of the ROD fungi.

2) Avoid injuring ʻōhiʻa. Wounds serve as entry points for the fungus and increase the odds that the tree will become infected and die from ROD. Avoid pruning and contact with heavy equipment wherever possible.

3) Clean gear and tools, including shoes and clothes, before and after entering the forest and areas where ʻōhiʻa may be present. Brush all soil off tools and gear, then spray with 70% rubbing alcohol. Wash clothes with hot water and soap.

4) Wash your vehicle with a high-pressure hose or washer if you’ve been off-roading or have picked up mud from driving. Clean all soil off tires–including mountain bikes and motorcycles–and vehicle undercarriage.

5) Don’t move ʻōhiʻa wood or ʻōhiʻa parts, including adjacent soil. The disease can be spread to new areas by moving plants, plant parts, and wood from infected areas to non-infected areas.

©Jan TenBruggencate 2018

Missing Hawaiian humpback whales? They're staying late in Alaskan waters, but it's still not certain why.

Hawai`i's humpback whales are missing, and now there are new clues about why.

In Hawai`i as well as other southern migration areas, steep declines in whale numbers are being reported. Researchers in Alaskan waters now report that they're seeing whales that are staying in northern waters instead of migrating.

(Image: Humpback in Sitka Sound, Mt. Edgecumbe: Humpback whale flukes are visible just on the surface with Mt. Edgecumbe on the horizon in Sitka, Alaska Sunday, October 28, 2018. Credit: Seanna O’Sullivan/UAS.)

What's not yet clear is whether they will just delay migration, perhaps because of warmer conditions in areas like Sitka Sound, or whether they can't migrate because changes in food availability have deprived them of the energy for the 30-day migration.

It is also not yet clear whether the delayed or omitted migrations will impact populations. Humpback whales make the trip to southern waters to give birth to their young.

“We are concerned that the offshore warm water anomaly known as 'the blob' and other ocean conditions has had a negative impact on humpback whale prey.” said Ellen Chenoweth, a UAS Adjunct Professor at University of Alaska Fairbanks.

Researchers are trying to raise the funds to figure out what's going on, she said.  It is not just that the whales are staying longer, but there are indications they are in distress. A release from the University of Alaska Southeast suggests there's something serious going on: "The researchers noted that they are seeing fewer calves, skinnier whales and more whales staying longer into winter feeding on herring, partially migrating and returning or possibly not migrating at all."

“We would like to quantify the changes in the numbers and distribution of whales present in winter and try to get at the cause and effect. But we need more monitoring funds. This means we need gas in the boat, time to be out there later in the season and, more technicians to manage the data and document the whales and more time on the water,” Chenoweth said.

The UAS Whale Research and Education Support fund will support the research. Donations can be made here. 

The dramatic change in migration habits mars a textbook success story in whale conservation.

Humpback whale populations had been drawn so low by whaling that they were listed as endangered in 1973 under the Marine Mammal Protection Act. 

By the 1980s, numbers that winter in Hawai`i had risen from a few thousand to more than 11,000. Almost all of those whales summer in southeastern Alaskan waters where the feed on schools of capelin, juvenile walleye pollock, sand lance, Pacific herring and krill.  

The dramatic increase in humpback populations continued into the 2010s, but appeared to stop and then drop a couple of years ago.

“There is a substantial decline in the number of whales we’re seeing. But when we look very closely at least in the waters off Lahaina (Maui), which is where most of the whales congregate, that decline is very much accounted for by the drop in the number of mother and calf pairs,” said Rachel Cartwright, a California State University researcher who heads the Keiki Kohola project.

An Associated Press story reviewed the reports of declining whale numbers in the islands. 

Cartwright said that reduced food supplies in the northern feeding waters are among the suspects for the decline. Chenoweth said Alaskan fisheries officials are also concerned about the impact of feeding whales on winter populations of schooling herring.

Early indications are that the first decline in humpback whales was caused by direct killing of the animals by the whaling fleets of the 1800s and 1900s. The cause of the new decline may be indirect: the impact of climate change on water temperatures and prey availability. 

©Jan TenBruggencate 2018