Survey assessing different practices for mechanical winter pruning in Southern France vineyards

Abstract

Context and purpose of the study – Winter pruning is today the longest operation for hand workers in the vineyard. Over the last years, mechanical pruning practices have become popular in southern France vineyards to respond to competitiveness issue especially for the basic and mid-range wine production. Wine farmers have developed different vineyard management techniques associated with mechanical winter pruning. They sought to be precise or not to control the buds number per vine. They maintained the vertical trellis system or grew the vine on a free cordon. They transformed the vineyard in minimal pruning system. The purpose of this survey was to assess a state of the practices in southern France vineyards, around 255 000 ha, which 2/3 are producing basic and mid-range wines.

Material and methods –  The survey was built on two steps. The first one was a qualitative follow-up with individual interviews on targeted winegrowers or cooperative’s technical managers who have been leaders in mechanical winter pruning development. These interviews allowed to build the second step survey. This second step consisted in a quantitative approach with an online questionnaire for winegrowers. It was composed by 43 to 63 closed-ended questions, with different fields such as farm characteristics, vineyard and soil management, vine-plot description and mechanical pruning operations. Statistical treatments were run with Addinsoft XLStat software.

Results – Results showed that there are three main mechanical pruning (mechaP) practices: a precise and a hedge mechaP, leaving lengths of branches respectively inferior or superior to 20 cm above the cordon line, and at last a minimal pruning system with few trimming operations on the canopy. Precise mechaP appears to be the most used technique with around 80% of the responses followed by the minimal pruning system, 15% of the responses, and the hedge mechaP with 5%. 56% of the estates are using mechanical pruning combined with trellised vertical shoot positioning (VSP) system, 22% with the free cordon system and 22% are using both systems.
Economic save is the main motivation to develop mechaP, due to the time save with winter pruning, followed by the difficulty to find handwork forces. The main gain observed by the producers due to mechaP is the increase and the regularity of the yield that impact positively the turnover per hectare. Finally, they consider that mechaP allows a better staff management due to time savings during the winter operations in the vineyard and a global increase of the economic value of the production.