[en] Microwave heating was recently approved by the FAO as a significantly effective phytosanitary treatment for wood packaging material. According to ISPM 15 (FAO 2009), the target organisms are eradicated if a temperature higher than 60 °C is maintained for 60 s across the entire profile of the board (i.e. 60 °C/60 s). A study using pallet boards was carried out in order to set up a treatment program that would meet ISPM 15 requirements in terms of wood temperature and insect mortality. A 4 m-long industrial tunnel oven (maximum power of 28.8 kW) was used to carry out the experiments. Temperature was measured by means of a VarioCAM® infrared camera. The most relevant results we found were: (i) achieving a temperature of 63.2 °C (Populus sp.) or 64.8 °C (Pinus sylvestris L.) on the upper surface of 22 mm-thick boards enabled compliance with FAO requirements (i.e. 60 °C/60 s), whatever the moisture content, basic density and initial temperature of the wood (provided the latter exceeded 0 °C); (ii) larvae >150 mg represented the most microwave-resistant life stage of Hylotrupes bajulus L.; (iii) the mortality rate of the larvae was influenced by the moisture content of the boards. Using the Gompertz model, we estimated the upper surface temperature that would be needed to achieve a 99.99683% mortality rate (the Probit 9 mortality level of efficacy) for the most microwave-resistant life stage of H. bajulus. This temperature was estimated to be 46.8 °C and 57 °C for wood with >50 and <25% moisture content, respectively.
Name of the research project :
Mise au point d’une méthode de traitement par micro-ondes des bois d’emballage destinés à l’exportation comme alternative aux mesures phytosanitaires actuellement appliquées (bromure de méthyle et traitement thermique).
FPS Health Federal Public Service Health, Food Chain Safety and Environment [BE]
SPW DG03-DGARNE - Service Public de Wallonie. Direction Générale Opérationnelle Agriculture, Ressources naturelles et Environnement [BE]
ULiège. GxABT - Liège Université. Gembloux Agro-Bio Tech [BE]