Pruning Impact on Sap Flux and GTD Risk

This technical document evaluates alternative pruning strategies in viticulture to reduce Grapevine Trunk Diseases (GTDs). It examines how traditional pruning creates large wounds that disrupt sap flow and increase necrosis and infection risks. The Guyot-Poussard system, developed in France, positions wounds on upper perennial wood to preserve sap transport and reduce disease susceptibility. Studies show this method reduces wound surface area on perennial wood compared to conventional systems, though retraining requires more labor initially. Field trials in Germany (Petgen, 2016) support its potential for improving vine health and sap flow, particularly in structured red wine production. Long-term efficacy remains under evaluation due to GTD’s 10-year incubation period. Challenges include labor demands, variety-specific adaptation, and training needs. The method is being tested in Gobelet and Pergola systems, but results are unconfirmed. Evidence is based on field observations and 219 sources.