Phenology of the Mencía Variety Cultivated in a Territory Included in the UNESCO World Network of Biosphere Reserves The study of grapevine phenology is very useful for vineyard management and control, as it allows the application of phytosanitary treatments at the phenological stages where the crop is most susceptible to different diseases, mainly cryptogamic. This work describes the phenological behaviour of the red Mencía variety, the most common in the Ribeira Sacra Designation of Origin (Northwest Spain), as well as its thermal requirements throughout its vegetative cycle. It has been carried out in a vineyard located in the highest areas of the Sil River canyon, during the year 2021. The observations were made on 10 vines and the phenological scale used was the one standardized by the BBCH. The vegetative cycle, from the beginning of sprouting to the harvest, took 163 days, during which 5097 GDD (Growing Degrees-Days) were accumulated. In agronomic, economic, social, histori...