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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Plant Genetic Resources and Disease Research » Research » Publications at this Location » Publication #366953
Research Project: Management, Characterization, and Evaluation of Pacific Tropical and Subtropical Fruit and Nut Genetic Resources and Associated Information

Location: Tropical Plant Genetic Resources and Disease Research

Title: Pathogenicity, symptom development and colonization of Metrosideros polymorpha by Ceratocystis lukuohia

Author
item HUGHES, MARC - University Of Hawaii
item JUZWIK, JENNIFER - Us Forest Service (FS)
item HARRINGTON, TOM - Iowa State University
item Keith, Lisa

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2020
Publication Date: 6/18/2020
Citation: Hughes, M.A., Juzwik, J., Harrington, T.C., Keith, L.M. 2020. Pathogenicity, symptom development and colonization of Metrosideros polymorpha by Ceratocystis lukuohia. Plant Disease. 104(6):2233-2241. https://doi.org/10.1094/PDIS-09-19-1905-RE.
DOI: https://doi.org/10.1094/PDIS-09-19-1905-RE

Interpretive Summary: Rapid 'ohi'a death (ROD) has led to extensive mortality of Metrosideros polymorpha ('ohi'a) trees on Hawai'i Island and has recently been discovered on Kaua’i, Maui and Oahu. Both Ceratocystis lukuohia and C. huliohia have been associated with ROD, although C. lukuohia appears to be the more important pathogen. Crown observations and dissections of forest trees either wound-inoculated with, or naturally-infected by, C. lukuohia were conducted to confirm pathogenicity and document patterns of host colonization. In pathogenicity trials, one of three and two of three trees inoculated with the fungus in February and August, respectively, exhibited crown wilt symptoms at 92 and 69 days after inoculation. Extensive radial black staining of the sapwood was found in main stems of five of six trees, while no crown wilt or xylem staining was found in control trees. Xylem staining, necrotic phloem and fungus presence was noted in six trees inoculated in May to June and harvested 37 to 42 days later, and these observations were compared to those in two naturally-infected and actively-wilting trees felled in early August. Contiguous xylem staining was found in the main stems and into the crowns of all trees, while discontinuous streaks of xylem staining extended into the main forks or side branches. Necrotic phloem associated with xylem staining occurred on the lower stems of inoculated trees. Aside from the necrotic phloem and radial staining of the sapwood, symptom development in 'ohi'a infected with C. lukuohia is similar to that of other systemic wilt diseases on hardwood trees.

Technical Abstract: Rapid 'ohi'a death (ROD) has led to extensive mortality of Metrosideros polymorpha ('ohi'a) trees on Hawai'i Island and has recently been discovered on Kaua’i, Maui and Oahu. Both Ceratocystis lukuohia and C. huliohia have been associated with ROD, although C. lukuohia appears to be the more important pathogen. Crown observations and dissections of naturally and artificially infected trees were conducted to confirm pathogenicity and document patterns of host colonization in forest trees.