Evaluation of the diagnostic feasibility of the electronic nose in detecting incipient decay of artificially inoculated wood

The tree stability-assessment methodology currently used in Italian cities initially follows a visual analysis of individual trees, followed by an evaluation of the internal state using different instruments that are often invasive, expensive, or cannot be effectively used in the urban environment. Moreover, many of these instruments do not provide an adequate evaluation of decay that occurs in the root system. The aim of this research was to evaluate the possibility of integrating tools currently used for assessments of tree decay in the urban environment with innovative techniques used in other fields and industries for various applications, such as quality control, environmental monitoring, medical diagnoses, and perfumery. The electronic nose (e-nose) was tested for its capability of detecting volatiles released by wood decay fungi, healthy trees, and diseased trees. Two different types of e-noses, based on different technologies, also were compared to determine the feasibility of detecting incipient decays in artificially-inoculated wood. All e-nose devices were capable of discriminating between healthy and artificially-inoculated wood with very high levels of precision and confidence. The e-nose utilizing polypyrrole-coated quartz microbalances with acoustic wave sensor array provided better results than the other technology (metal-oxide gas sensors) in discriminating woody samples containing different agents of wood decay.