I am currently pursuing a PhD in forest sciences at Université Laval in Quebec City, where I have been enrolled since 2024. My research focuses on a tree disease affecting oaks: oak wilt, caused by the fungus oak wilt (Bretziella fagacearum). This disease leads to the systematic death of its host once infected, with the time to mortality depending on the oak species involved. White oak species can survive for a few years after infection, whereas red oak species may die within just a few weeks.
Currently, this disease is mainly detected through the observation of wilting symptoms. Unfortunately, at this stage it is often already too late, as the pathogen may have already spread to neighbouring trees either through root grafts or via insect vectors carrying fungal spores. It is within this context that my project is positioned, aiming to develop a new early detection method, prior to symptom appearance, by using Volatile Organic Compounds (VOCs) produced by plants.
Volatile Organic Compounds (VOCs) are molecules naturally produced by trees that fulfill a wide range of biological functions. The full set of these molecules constitutes what is referred to as a VOC profile. This profile can vary both in terms of the types of molecules present and their relative abundance. These variations can be observed between different tree species, across geographic locations, but also within a single group, depending on factors such as individual age, health status, or light exposure. In particular, changes in VOC profiles can be associated with shifts in plant health status, which is what we aim to detect in the context of disease studies. To do so, we use a push–pull sampling system based on a pump that allows the collection of emitted molecules onto adsorbent tubes. These tubes are then analyzed using gas chromatography coupled with mass spectrometry, which enables the identification of the compounds present.
These measurements are carried out on young oak trees grown in controlled greenhouse conditions, where trees are artificially infected. They are also performed in the field in Michigan on mature trees that are naturally infected under real environmental conditions.