The transcontinental trade of roundwood requires thorough phytosanitary treatment to protect native flora and fauna against foreign pests. This is generally done by fumigating shipping containers packed with roundwood with sulfuryl fluoride, a potent greenhouse gas. After treatment, the gas is released into the atmosphere, causing massive emissions. Since 2017, the usage of sulfuryl fluoride in the Port of Hamburg has multiplied up to twelvefold from 19 t to a maximum of 230 t in 2020 as a result of increased roundwood exports due to the ongoing bark beetle-calamity in Germany. Therefore, an alternative treatment method is sought. Thermal treatment using dry heat is considered as an alternative to sulfuryl fluoride fumigation. This method is currently used for the treatment of wood packaging material in accordance with the International Standard for Phytosanitary Measures 15 by the International Plant Protection Convention. The standard lists the requirements for successful treatment as such: “[…] the fundamental requirement is to achieve a minimum temperature of 56 °C for a minimum duration of 30 continuous minutes throughout the entire profile of the wood (including its core)”. The presented study aimed at investigating the suitability of thermal treatment for phytosanitary treatment of roundwood against bark-breeding beetles. Norway spruce (Picea abies) stem sections of varying diameters were heated at 70 – 100 °C with temperature sensors equipped at their geometrical core, which recorded the entire heating and cooling process. The treatment duration under favorable air flow conditions ranged between 1.5 hours for smaller logs at 100 °C and up to ten hours for medium-sized logs at 70 °C. Additionally, sensor-equipped infested logs were exposed to dry heat and examined for the presence of live and dead beetles of all stages of development during summer and winter, and potential for fungal growth. So far, results during summer conditions are promising, meaning no live beetles originating from these infested logs were found. The comparison of fungal growth from samples extracted from the logs prior to and post-treatment showed a reduction, so treatment also appeared to be somewhat effective in reducing fungi.

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