Olive leaves of Picholine and Olivière varieties (used for the production of olive oil) were collected in March 2022, in the Hérault department, of the Occitanie region of France (latitude 43.5912356, longitude 3.2583626). The leaves were immediately removed and stored in cardboard boxes protected from light and humidity until analysis in June 2022. Leaves of four other, mainly ornamental varieties, were collected locally and analysed in order to provide additional data for the validation study; These varieties could not be identified, but insofar as could be established, they are Italian or Greek hybrids; in the interest of simplicity, these varieties were named UNK 1, UNK 2, etc.