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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 #386268
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: Vacuum steam treatment of Metrosideros polymorpha logs for eradication of Ceratocystis huliohia and C. lukuohia

Author
item JUZWIK, JENNIFER - Us Forest Service (FS)
item HUGHES, MARC - University Of Hawaii
item CHEN, ZHANGJING - Virginia Polytechnic Institution & State University
item YANG, ANNA - Us Forest Service (FS)
item Keith, Lisa
item WHITE, MARSHALL - Virginia Polytechnic Institution & State University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2021
Publication Date: 4/1/2022
Citation: Juzwik, J., Hughes, M.A., Chen, Z., Yang, A., Keith, L.M., White, M.S. 2022. Vacuum steam treatment of Metrosideros polymorpha logs for eradication of Ceratocystis huliohia and C. lukuohia. Plant Disease. 106(4):1114-1121. https://doi.org/10.1094/pdis-07-21-1424-re.
DOI: https://doi.org/10.1094/pdis-07-21-1424-re

Interpretive Summary: The discovery of a new and devastating disease, rapid ohia death (ROD), in Hawaii led to a state quarantine that regulates inter-island transport of ohia wood and plant material to prevent spread of the causal pathogens. Heat treatments of ohia logs in commercial trade were considered for phytosanitary treatment. Vacuum steam (VS) was evaluated for its ability to eradicate the ROD pathogens, Ceratocystis lukuohia or C. huliohia, in main stem logs from ROD-affected forest trees. Results demonstrate VS is an effective and efficient method for treating large diameter ohia logs that mill owners and regulatory plant pathologists can consider for use in Hawaii.

Technical Abstract: The discovery of a new and devastating disease, rapid ohia death (ROD), in Hawaii led to a state quarantine that regulates inter-island transport of ohia wood and plant material to prevent spread of the causal pathogens. Heat treatments of ohia logs in commercial trade were considered for phytosanitary treatment. Vacuum steam (VS) was evaluated for its ability to eradicate the ROD pathogens, Ceratocystis lukuohia or C. huliohia, in main stem logs from ROD-affected forest trees. Replicate loads of three de-barked logs (24 to 43 cm diameter; 1.7 to 2.0 m long) were VS-treated at 56° C for 30 min or 60° C for 60 min at a sapwood depth equal to 70% of log radius. Mean frequencies of pretreatment and control log fungus colonization ranged from 12 to 16% and 21 to 25% based on carrot-baiting assays of thin wood strips taken from inner and outer sapwood, respectively, of two disks per log. No viable Ceratocystis was detected in either sapwood locations for the 60° C/ 60 min schedule or for the inner locations for the 56° C/ 30 min schedule following treatment. Only one subsample (0.42%, n=240) of logs of the latter treatment yielded Ceratocystis. Time required for treatment ranged from 7.4 to 15 h for the 56° C/ 30 min schedule and from 8.6 to 19.2 h for the 60° C/ 60 min schedule. These results demonstrate VS is an effective and efficient method for treating large diameter ohia logs that mill owners and regulatory plant pathologists can consider for use in Hawaii.