HAWAII FORESTRY EXTENSION

Dr. J. B. Friday
CTAHR | University of Hawaiʻi
Cooperative Extension Service
875 Komohana Street
Hilo, HI 96720
Telephone: (808) 969-8254
Fax: (808) 981-5211
Email: jbfriday@hawaii.edu

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Rapid ʻŌhiʻa Death | Ceratocystis Wilt of ʻŌhiʻa

Ohia with Rapid Ohia Death (Ceratocystis)

A newly identified disease has killed large numbers of mature ʻōhiʻa trees (Metrosideros polymorpha) in forests and residential areas of the Puna and Hilo Districts of Hawaiʻi Island. Landowners have observed that when previously healthy-looking trees begin to exhibit symptoms they typically die within a matter of weeks. Pathogenicity tests conducted by the USDA Agriculture Research Service have determined that the causal agent of the disease is the vascular wilt fungus, Ceratocystis fimbriata (Keith and others 2015). Although a different strain of Ceratocystis fimbriata has been present in Hawaiʻi as a pathogen of sweet potato for decades (Brown and Matsuura, 1941), this is a new strain of the fungus and the first record of any Ceratocystis species affecting ʻōhiʻa. It is not yet known whether this widespread occurrence of ʻōhiʻa mortality results from an introduction of an exotic strain of the fungus or whether this constitutes a new host of an existing strain.  This disease has the potential to kill ʻōhiʻa trees statewide.

J.B. Friday

J. B. Friday
University of Hawaiʻi College of Tropical Agriculture and Human Resources Cooperative Extension Service
jbfriday@hawaii.edu
(808) 969-8254

Lisa Keith conducting pathology tests on ohia.

Lisa Keith
USDA Agriculture Research Service
Daniel K. Inouye Pacific Basin Agriculture Research Center
Lisa.Keith@ars.usda.gov
(808) 959-4357

Flint Hughes samples ohia

Flint Hughes
USDA Forest Service Institute of Pacific Islands Forestry
fhughes@fs.fed.us
(808) 854-2617


May 10, 2016

Rapid ‘Ōhi‘a Death Briefing Document provided to Governor Ige on May 10, 2016. For a summary of the issue, refer to the ROD Briefing document dated February 10, 2016.

April 13, 2016

Updated map of sites where Ceratocystis wilt has been confirmed. 

April 2016: Updated map of sites where Ceratosystis wilt has been confirmed.

March 29, 2016

The Hawaii Board of Agriculture approved permit conditions for the movement of all soil from Hawaiʻi Island, which were added to the current interisland quarantine to prevent the spread of rapid ʻōhiʻa death (ROD).

HDOA has also created posters and flyers to warn travelers not to transport ʻōhiʻa materials, including lei, from Hawaiʻi Island to any other island.

March 24, 2016

A lei of red and yellow ‘ōhi‘a blossoms bordered by palapalai ferns by Kalei Cadawas. Kauluwehi lei contest, Hilo, Hawaii. Photo: JB FridayCommunity leader, Kekuhi Kealiʻikanakaʻoleohaililani, writes a letter to the hula community (read letter here) sharing her aloha and concern for our beloved ʻōhiʻa, and suggests ways for the hula community to be actively involved in preventing the spread of C. fimbriata, and helping to heal our ʻōhiʻa ʻohana. For the 2016 Merrie Monarch Festival in Hilo, Hawaiʻi, Kekuhi is working with other Hawaiʻi Island community members to host the Puaʻenaʻena Ceremony. This fire ceremony will provide a way for people to offer their kinolau, hakina, lei, and kūpeʻe with thoughts of full recovery for our ʻŌhiʻa to the fire of Ke Ahi O Hiʻiaka (see invitation announcement here).

February 5, 2016

Seeding the Future of the ohia treeConservationists at the UH Lyon Arboretum have launched a new effort to save seeds from ʻōhiʻa trees statewide to help with scientists search for resistant varieties and aid in eventual restoration efforts. UH faculty J. B. Friday, Sheila Conant, and Kalena Silva explain the threat ROD poses to the Hawaiian forest, native birds, and Hawaiian culture in this video: https://www.youtube.com/watch?v=vggJyLFvv5Q. Marian Chau, director of the Lyon Arboretum seed lab, explains how seed banking can help. The effort is being supported by a crowdfunding campaign at http://friendsoflyon.com/ohialove/.

January 27, 2016

34,00 acres affected by RODAn aerial survey conducted by the Hawaii DLNR Division of Forestry and Wildlife, the USDA Forest Service, the Big Island Invasive Species Committee, and Hawaii Volcanoes National Park staff of 810,000 acres of ʻōhiʻa forests on Hawaii Island has shown that the extent of Rapid ‘Ōhi‘a Death is much wider than previously thought. Surveyors estimated the current extent of the infestation at 34,000 acres. While the heart of the infestation remains in lower Puna, the surveys revealed a growing area infected by ROD in Kona and possible new infestations in Hamakua and Kohala, areas which had not been affected before. DOFAW staff are following up in sampling to confirm infection in new areas of the island. Rapid ‘Ōhi‘a Death has not been found on any of the other Hawaiian islands. Read more in the state DLNR news release.

December 24, 2015

The Hawaii Department of Lands and Natural Resources has produced a new video about Rapid ‘Ōhi‘a Death and what people can do to reduce the spread of the disease.

October 30, 2015

ROD on Facebook Connect with the Rapid ʻŌhiʻa Death page on Facebook.

October 27, 2015

ʻŌhiʻa samples from Holualoa and Kealakekua on the Kona side of Hawaiʻi Island have been confirmed to be infected with Ceratocystis.

October 20, 2015

Videos on Rapid ʻŌhiʻa Death from the 2015 Hawaiʻi Conservation Conference now available on-line.

October 9, 2015

Rapid ‘Ōhi‘a Death: A House on Fire (video)
After Dark at the Park, Hawaii Volcanoes National Park, 29 Sept 2015

Join research plant pathologist Lisa Keith of the Pacific Basin Agricultural Research Center, Flint Hughes, Research Ecologist with USDA Forest Service Institute of Pacific Islands Forestry and J.B. Friday, University of Hawaiʻi College of Tropical Agriculture and Human Resources as they provide an update on this new threat to Hawaii's native forests. Research so far has determined that within two to three years of detection, a majority of trees in some measured stands have succumbed to the disease. This means the fungus has the potential to threaten forests statewide, resembling not so much a tree disease as a house on fire. (1 hour)

August 2015

August 25, 2015: Board of Agriculture Restricts Movement of ʻŌhiʻa Plants from Hawaiʻi Island: The Hawaiʻi Board of Agriculture today approved an interim rule that imposes a quarantine on the intrastate movement of ʻōhiʻa plants and plant parts, including flowers, leaves, seeds, stems, twigs, cuttings, untreated wood, logs, mulch greenwaste and frass (sawdust from boring beetles) from the Island of Hawaiʻi. Transport of such items may be only conducted with a permit issued by the Hawaiʻi Department of Agriculture. The interim rule will also restrict the movement of soil from Hawaiʻi Island beginning in January 2016. The interim rule will go into effect when it is published in the newspapers within 12 days and will be in force for one year.  Read the full press release here. http://hdoa.hawaii.gov/blog/main/ohiaquarantine/

July 23, 2015

Rapid ʻŌhiʻa Death ~ ʻŌhiʻa Wilt: Sampling ʻŌhiʻa trees for infection with Ceratocystis fimbriata

See a short video on how to take samples from ʻōhiʻa suspected of having Ceratocystis wilt or Rapid ʻŌhiʻa Death. WARNING: Injuring ʻōhiʻa trees like this may kill them. Be sure the tree you are cutting is already dying. On Hawaiʻi Island, samples may be submitted to Dr. Lisa Keith, USDA, Agriculture Research Service, Daniel K. Inouye Pacific Basin Agriculture Research Center; Lisa.Keith@ars.usda.gov; 808-959-4357. On other islands samples may be submitted to the Hawai‘i Department of Agriculture (HDOA) Plant Quarantine Branch (PQB) on each island. (July 2015)

 

June 25, 2015

The Hawaiʻi Department of Agriculture has agreed to collect samples from landowners who suspect that their trees may have ʻōhiʻa wilt on Oʻahu, Maui, Kauaʻi, Molokaʻi, and Lanaʻi and transport these samples to Hawaiʻi Island for analysis. Samples may be dropped off at the Hawaiʻi Department of Agriculture (HDOA) Plant Quarantine Branch (PQB) on each island. Please see their web page for information on how to take samples and locations of offices. Landowners on Hawaiʻi Island who suspect ʻōhiʻa wilt should contact Drs. Friday, Hughes, or Keith (addresses above).

June 22, 2015

Ceratocystis fimbriata has been recovered from the frass or sawdust emitted by boring beetles attacking infected trees. In other forests, wind-blown insect frass is a source of new infections. It is currently unknown whether insects transmit ʻōhiʻa wilt or whether they merely attack diseased trees.


April 27, 2015

Introduction

A newly identified disease has killed large numbers of mature ʻōhiʻa trees (Metrosideros polymorpha) in forests and residential areas of the Puna and Hilo Districts of Hawaiʻi Island. Landowners have observed that when previously healthy-looking trees begin to exhibit symptoms they typically die within a matter of weeks. Pathogenicity tests conducted by the USDA Agriculture Research Service have determined that the causal agent of the disease is the vascular wilt fungus, Ceratocystis fimbriata (Keith and others 2015). Although a different strain of Ceratocystis fimbriata has been present in Hawaiʻi as a pathogen of sweet potato for decades (Brown and Matsuura, 1941), this is a new strain of the fungus and the first record of any Ceratocystis species affecting ʻōhiʻa. It is not yet known whether this widespread occurrence of ʻōhiʻa mortality results from an introduction of an exotic strain of the fungus or whether this constitutes a new host of an existing strain.  This disease has the potential to kill ʻōhiʻa trees statewide.

Figure 1. Forest stand affected by Ceratocystis wilt. Image credit: Pictometry International

Forest stand affected by Ceratocystis wilt. Photo: Pictometry International

Extent

The disease affects non-contiguous forest stands ranging from 1 to 100 acres. As of 2014, approximately 6,000 acres from Kalapana to Hilo on Hawaiʻi Island had been affected with stand showing greater than 50% mortality. The disease has not yet been reported on any of the other Hawaiian Islands.

Symptoms

Crowns of affected trees turn yellowish (chlorotic) and subsequently brown within days to weeks; dead leaves typically remain on branches for some time (Figure 1). On occasion, leaves of single branches or limbs of trees turn brown before the rest of the crown of becomes brown (Figure 2). Recent investigation indicates that the pathogen progresses up the stem of the tree. Trees within a given stand appear to die in a haphazard pattern; the disease does not appear to radiate out from already infected or dead trees. Within two to three years nearly 100% of trees in a stand succumb to the disease. Other trees in the forest such as kōpiko (Psychotria spp.), ʻohe mauka (Polyscias spp.), strawberry guava (Psidium cattleianum), Melastoma spp., and Koster’s curse (Clidemia hirta) are not affected by the disease.

Symptoms of Ceratocystis wilt of ʻōhiʻa include rapid browning of affected tree crowns.

Symptoms of Ceratocystis wilt of ʻōhiʻa include rapid browning of affected tree crowns.

Symptoms of Ceratocystis wilt of ‘ōhi‘a include rapid browning of affected tree crowns. Morality on the right half of a fork in an ‘ōhi‘a tree infected with Ceratocystis.

Figure 1. (above left) Symptoms of Ceratocystis wilt of ʻōhiʻa include rapid browning of affected tree crowns.
Figure 2. (above right) Mortality on the right half of a fork in an ʻōhiʻa tree infected with Ceratocystis.

Ceratocystis manifests itself as dark, nearly black, staining in the sapwood along the outer margin of trunks of affected trees. The stain is often radially distributed through the wood (Figures 3 and 4). Wood samples incubated under moist conditions in plastic bags for a week produce characteristic fruiting bodies of Ceratocystis called perithecia (Figure 7).

Cross section of an infected ʻōhiʻa showing the characteristic dark staining of sapwood caused by Ceratocystis. Figure 5. (above right) Close up of characteristic dark staining of sapwood from Ceratocystis.

Figure 3. (above left) Cross section of an infected ʻōhiʻa showing the characteristic dark staining of sapwood caused by Ceratocystis.

Figure 4. (above right) Close up of characteristic dark staining of sapwood from Ceratocystis.

Cross section of an infected ʻōhiʻa showing the characteristic dark staining of sapwood caused by Ceratocystis.

Fig. 5 (above): Cross section of an infected ʻōhiʻa showing the characteristic dark staining of sapwood caused by Ceratocystis.

Fig. 6 (below): Bark slash of an ʻōhiʻa tree showing tangential view of dark staining of sapwood from Ceratocystis infection.

Figure 5. Bark slash of an ‘ōhi‘a tree showing tangential view of dark staining of sapwood from Ceratocystis infection.

Figure 7. (below) Perithecia, or fruiting bodies, of Ceratocystis.

Figure 6. Perithecia, or fruiting bodies, of Ceratocystis.

Not all wood stains in ohia are caused by Ceratocystis. The following photographs were taken of wood samples submitted to the laboratory that did not test positive for Ceratocystis. (Click on photo to view larger image.)

Not C. fimbriata: Solid black staining in bark and cambium Not C. fimbriata: Unusual blotchy pattern Not C. fimbriata: Unusual blotchy pattern

Not C. fimbriata: Dark brown staining Blotchy staining mostly in heartwood

Methods of transmission

It is not yet known how the disease spreads from tree to tree or from forest stand to forest stand. In other Ceratocystis plant hosts such as sweet potato, cacao, mango and eucalyptus the fungus is moved by insects, soil, water, infected cuttings, pruning wounds, or tools, and these modes of transmission may also be involved in infections of ʻōhiʻa trees and stands (Harrington n.d.). Ceratocystis has been found in soils under infected stands in Hawaii and contaminated soil may transmit the disease.

What to do

As of early 2015 the disease was confined to Hilo and the Puna district on Hawaiʻi Island. Landowners who suspect Ceratocystis infection of ʻōhiʻa trees outside these areas are encouraged to contact Drs. Friday, Hughes, or Keith at the above addresses with reports and locations of infected areas. Digital photographs of crowns of infected trees and wood showing the characteristic staining will help in assessing likelihood of an infection.

Currently, there is no effective treatment to protect ʻōhiʻa trees from becoming infected with Ceratocystis or cure trees that exhibit symptoms of the disease. To reduce the spread of Ceratocystis, landowners should not transport wood of affected ʻōhiʻa trees to other areas. The pathogen may remain viable for over a year in dead wood. Tools used for cutting infected ʻōhiʻa trees should be cleaned either with Lysol ™ or a 70% rubbing alcohol solution. A freshly prepared 10% solution of chlorine bleach and water can be used as long as tools are oiled afterwards, as chlorine bleach will corrode metal tools. Chain saw blades should be brushed clean, sprayed with cleaning solution, and run briefly to lubricate the chain. Vehicles used off-road in infected forest areas should be thoroughly cleaned underneath so as not to carry contaminated soil to healthy forests. Shoes, tools, and clothing used in infected forests should also be cleaned, especially before being used in healthy forests.

ReferenceS

Brown, A. C. and M. Matsuura. 1941. Black rot of sweet potato. Agricultural Extension Circular #134, University of Hawaii.

Harrington, T. Diseases caused by Ceratocystis species. http://www.public.iastate.edu/~tcharrin/CeratoDis.html (accessed April 27, 2015)

Keith, L. M., R. F. Hughes, L. S. Sugiyama, W. P. Heller, B. C. Bushe, and J. B. Friday. 2015. First Report of Ceratocystis wilt on ʻŌhiʻa. Plant Disease. http://dx.doi.org/10.1094/PDIS-12-14-1293-PDN

Oak Wilt is a similar disease to ʻŌhiʻa Wilt. Two references on Oak Wilt are:

  1. US Forest Service: Oak Wilt http://www.na.fs.fed.us/spfo/pubs/fidls/oakwilt/oakwilt.htm
  2. University of New Hampshire:  Oak Wilt – A New Threat to New England  http://extension.unh.edu/resources/files/Resource000906_Rep966.pdf