Do UAVs help in the detection of grapevine yellows in vineyards that are difficult to reach?

The symptoms of the flavescence dorée and bois noir are grouped into the so-called Grapevine Yellows (GY). These diseases are affecting viticultural regions worldwide and all varieties and rootstocks seem susceptible but with varying degrees of severity. Typical symptoms include discolouration and necrosis of leaf veins and leaf blades, downward curling of leaves, lack of or incomplete lignification of shoots, stunting and necrosis of shoots, abortion of inflorescences and shriveling of berries. The compulsory control plan for the fight of these diseases includes both the use of insecticides and the eradication of the vines. This latter is part of a monitoring plan of the grapevine yellows that aims to identify outbreaks of the disease and its progression and limit the compulsory phytosanitary control only in the truly affected areas. The identification of the GY is very time-consuming technical work because each vineyard must be visually inspected plant by plant. This type of monitoring is made even more difficult in cases of steeply sloping vineyards and where the vineyard landscape is fragmented. So we raised the following question: is it possible to use UAVs (drones) to remotely monitor the vines that are difficult to reach and identify the grapevine yellows? We present here the results of our field tests made in Trentino (IT) with different drone models (prosumer and professional) and with different types of image acquisition sensors (RGB and multi-spectral)