Wood Innovations (Wood Products Markets, Wood Energy, Community Wood Energy and Wood Innovations Program, and Wood Education and Resource Center)

Heat Sterilization of Ash Firewood for Thermal Eradication of Emerald Ash Borer

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Wood Education and Resource Center (WERC)
University of Minnesota Duluth
Natural Resources Research Institute - CARTD
Wood Materials and Manufacturing Program
5013 Miller Trunk Highway
Duluth, MN 55811-1442
The project examined the practicality and effectiveness of heat treating schedules for eradicating Emerald ash borer (EAB) and other non-native insect species from ash firewood. Mathematical models were developed to calculate estimates of heating times. Field trials were performed in a convention dry kiln to determine the validity of the models for large scale heat treatment operations.
ash, dry kilns, Emerald ash borer, firewood, heat sterilization, invasive species, sanitization, Minnesota, heat treatment, dry heat, wet heat
US Forest Service Grant $ 44,804
Cooperative Funding $ 45,278
Total $ 90,082
Due to the potential risk associated with moving emerald ash borer (EAB) infested firewood, the interstate movement of all hardwood firewood is currently restricted under a federal quarantine.  Communities and firewood producers are now faced with decisions on how to treat their firewood for interstate commerce.  The new regulations for heat sterilization of ash firewood require holding a core temperature of 160°F (71°C) for 75 minutes, which is much higher than current heating standard for treating solid wood packaging materials (133°F (56°C) for 30 minutes).  Consequently, the heating schedules developed for wood packaging materials are not acceptable for treating ash firewood.  The goals of this project were to evaluate different heat treatment options that may suit for the needs of various firewood operations and develop heat treating schedules and heating time tables that will help communities and firewood producers to plan and execute effective heat treating operations.  In this project, we first conducted laboratory heating experiments using green and air-dried ash firewood and obtained heating time data for different heating schemes.  Mathematical models were developed to estimate heating times for the heating conditions that are not tested in the experiment.  Heating time tables, were developed for a series of heating temperatures and initial wood temperatures.  Our field heat treatment trail in a commercial dry kiln facility indicated a significant difference in heating times between the laboratory kiln runs and the field kiln run.  Although the size of kiln could have contributed to the increase of heating times in field trail, the type of kiln and heat source are the main factors that control the heating rate and result in differences in heating times.  More field heat treatment trails at different types of kiln facilities (steam, hot water, and direct fire) should be conducted in the future to calibrate the heating time tables developed through the laboratory experiments.
For detailed results of this project, please see the references below. Note: Portable Document Format (.pdf) files need a free reader; please read the USDA disclaimers regarding external links.
WERC Project Management Information System (WERC-PMIS)
Version 2.0.07 released on 1/12/2022. (Database last updated 2/13/2022 by Patrick Rappold.)
USDA Forest Service, State and Private Forestry, National Information Center