Heat sterilization of ash (Fraxinus spp.) firewood: Heat-treating options, temperature monitoring and thermal verification

Abstract

Because of the potential risk associated with moving emerald ash borer (EAB)-infested firewood, the interstate movement of all hardwood firewood in the USA is currently restricted under the Federal quarantine. Communities and firewood producers are now faced with decisions on how to treat their firewood for interstate commerce. The new US Federal regulations for heat sterilization of ash firewood require holding a core temperature of 71°C for 75 min, which is higher than current international standard for heat treating solid wood packaging materials (ISPM 15). A study funded by the US Forest Service Wood Education and Resource Center examined the efficacy of different heat-treatment schemes for meeting the new regulations and developed empirical models for estimating heating times under various heating conditions. This paper addresses some practical issues of the heat-treatment process in terms of meeting the current heating standard for EAB, monitoring temperature changes during heating process and providing thermal verification after the heat-treatment operations.