Detecting Chestnut Ink Diseases Through the Dog's Sense of Smell: From Laboratory to Forest

Chestnut ink disease, caused by Phytophthora spp., represents one of the main threats to the productivity and sustainability of sweet chestnut ( Castanea sativa ) in southern Europe. Early diagnosis is an essential step to develop appropriate management strategies. Therefore, this study investigates the potential of dogs' olfactory abilities to detect pathogen‐specific volatile organic compounds (VOCs) emitted by infected roots, offering a promising, non‐invasive approach for rapid and reliable disease detection in forest ecosystems. Hulk, a 7‐year‐old Labrador retriever, was trained through a multiphase protocol using GETXent polymer tubes soaked with Phytophthora VOCs under controlled conditions. His performance was then evaluated in greenhouses with artificially inoculated seedlings and in chestnut orchards under natural conditions. Statistical analyses showed that Hulk demonstrated positive Phytophthora detection skills throughout the training phases, both with polymer tubes and in the greenhouse and his performance remained consistently superior to random expectations. In chestnut orchards, Hulk revealed high sensitivity, showing signs of alert for 86% of trees displaying specific ink disease symptoms and for 75% of trees displaying nonspecific symptoms. Furthermore, the dog was shown to be efficient in intercepting early root infection on apparently asymptomatic trees, validated by laboratory analyses. In addition, VOCs related to Phytophthora infections were chemically identified as o ‐cymene, camphor and borneol. To our knowledge, this is the first application of canine detection using GETXent polymer tubes to train a dog for Phytophthora cambivora surveillance in chestnut orchards, which could have application in nursery stock to limit anthropogenic spread on a wide scale.