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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 #410936
Research Project: Conservation, Management, and Genetic Improvement of Tropical and Subtropical Fruit, Nut, and Beverage Crop Germplasm for the Pacific Region

Location: Tropical Plant Genetic Resources and Disease Research

Title: Pathogenicity and colonization of Metrosideros polymorpha by Ceratocystis huliohia

Author
item JUZWIK, JENNIFER - Us Forest Service (FS)
item HUGHES, MARC - Us Forest Service (FS)
item Keith, Lisa

Submitted to: Forest Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2024
Publication Date: 6/2/2024
Citation: Juzwik, J., Hughes, M.A., Keith, L.M. 2024. Pathogenicity and colonization of Metrosideros polymorpha by Ceratocystis huliohia. Forest Pathology. 54:e12865. https://doi.org/10.1111/efp.12865.
DOI: https://doi.org/10.1111/efp.12865

Interpretive Summary: Rapid 'Ohi'a Death (ROD), an emerging threat to the keystone forest tree, Metrosideros polymorpha (= 'ohi'a), is caused by both Ceratocystis lukuohia and C. huliohia. The disease caused by C. huliohia, the less aggressive fungal pathogen, is not clear. Crown observations and dissections of naturally and artificially infected trees were conducted to confirm pathogenicity and document patterns of host colonization in forest trees.

Technical Abstract: Both Ceratocystis lukuohia and C. huliohia have been associated with Rapid 'Ohi'a Death (ROD), an emerging threat to the keystone forest tree, Metrosideros polymorpha (= 'ohi'a). The vascular wilt disease caused by C. lukuohia has been recently described and is responsible for the widespread ROD epidemic on Hawai'i Island. However, the disease caused by C. huliohia is not clear. Artificial inoculation of field-grown 'ohi'a with C. huliohia and dissections of naturally infected, early symptomatic forest trees were conducted to confirm pathogenicity on field grown trees and the pattern of internal colonization. In two trials, crowns of trees whose main stems had been inoculated with C. huliohia were visually healthy at the time of tree harvest after 43 to 55 days for the first trial, and 91-days post-inoculation for the second trial. However, elliptical inner bark cankers underlain by reddish-brown xylem were associated with the inoculation points. Similar canker and stain symptoms were found on stems and branches of 'ohi'a (24 to 26 cm trunk diameter) naturally infected by C. huliohia. This xylem stain manifested as multiple distinct elliptical cankers or the coalescing of multiple cankers. The pathogen was commonly isolated from the perimeter of the stained outer sapwood and to a depth of 4 cm. The coalescence of multiple cankers was associated with the crown symptoms observed on the naturally infected forest trees that were dissected. Multiple C. huliohia infections that lead to coalescing cankers which subsequently girdle stems likely occurs over one or more years compared to the shorter time (e.g., months) required for C. lukuohia-caused death to occur.