This small insect under the leaf is a leafhopper

Not in itself a danger to the plant, but it turns out that this insect is the vector for the Flavescence Dorée phytoplasma. If in a parcel, a vine is affected by flavescence, this insect will carry it from vine to vine, potentially contaminating the entire plot. Each year, we cut down the vines affected by flavescence to prevent it from spreading. There is a mandatory treatment to carry out in early June, even if its effectiveness is widely open to debate. The only thing that works is to prevent its spread as much as possible by removing all affected vines. Fortunately, there are very few in our vineyards, and the vines we are asked to uproot are not always affected by flavescence.