Importance of quality maintenance pruning for young Ugni Blanc grapevines

This article investigates and models the effects of maintenance pruning quality on the initial formation of desiccation cones and wood necrotisation. Two different types of pruning, short and long pruning cuts, were performed annually for three years in two Charente vineyards. The short pruning type removed the diaphragm. In the long one, four modalities were applied: these ranged from keeping a 1 cm chicot above the diaphragm, to leaving a much longer one to preserve the bud. Neither of the trials, whether for short or long pruning, showed any correlation between necrosis length and spur diameter (R2 < 0.14 for both trials). Charente Ugni Blanc necrosis length, for long pruning, proved significantly more extensive 8 months after pruning, without damaging the diaphragm. Chicot necrotisation rates varied with each vintage, particularly in 2020, the year immediately following the first maintenance pruning. When long pruning cuts preserved 2–3 cm of cane above the diaphragm, the desiccation cones were blocked, leaving the sap flow unimpeded.