Development of a new non-invasive tool for the assessment of decays in the urban environment

The problem of tree stability in the urban environment is one of the main worries of our public administrations. The very bad conditions in which plants live in the cities force them to endure perennial stress, many various pests, and damage from accidental injuries. Currently, the stability methodology assessment in the urban environment initially follows a visual analysis of individual trees pursued by an evaluation of the internal state by using different instruments that are feasible but often invasive, expensive, or cannot be used in the urban environment. Moreover, many of these instruments do not provide an adequate evaluation if the decay occurs in the root system. We have evaluated the possibility of integrating the tools currently used with an innovative one developed in other fields for different applications: the electronic nose and its capability to detect volatiles emitted by the wood decay fungi, the healthy trees and the diseased trees. Results showed the feasibility of using three different e-noses for detecting incipient decays in artificially inoculated wood. A previous objective was to evaluate the progress kinetics of decays in trees in order to develop provisional models and that are reliable and applicable. Our data confirm that A. mellea and G. lucidum have the fastest growth rates among common urban wood decay fungi but Thuja occidentalis L. seems resistant or at least tolerant to many wood decay fungi based on artificial inoculations. Platanus x acerifolia appeared to be the most susceptible species of all ornamental tree species tested.