It is known that grapevine trunk diseases infect vines via pruning wounds. They colonise and spread throughout the vascular tissue affecting sap flow and subsequent vine performance. Researchers in Cognac tested different pruning techniques in young vines already trained to a Double Guyot system to investigate the relationship between wound diameter and necrosis length, short pruning vs long pruning necrotic patterns over time, and shoot fertility.
Project layout
Two vineyard sites were used to replicate the study in Ugni blanc vineyards in Charente. The two parcels were planted in 2014 and 2015, and the study was conducted from 2019 to 2021. Treatments included one short pruning practice where the previous season’s spur diaphragm was damaged and four long pruning practices leaving 1cm, 2-3cm or 5-6cm woody material (chicot) above the diaphragm. The diaphragm is located within a vine cane at each node and limits wood necrosis by compartmentalising each internode. Metrics included cut diameter, desiccation (drying out from the wound), necrosis volume and rates, and shoot fertility.
Main results
- No correlation was observed between spur diameter and necrosis length.
- No correlation was observed between pruning cut treatments and shoot fertility.
- Chicot necrosis lengths of the long pruning treatments were significantly greater eight months after pruning but did not damage the diaphragm.
- Chicot necrosis rates varied over vintages.
- The best results were observed where 2-3cm long cuts above the diaphragm were made, resulting in minimal sap flow disruptions.
Significance of the study
This study confirms previous findings suggesting no relationship between spur diameter and necrosis length. It also affirms the importance of pruners being familiar with vine anatomy to make correct pruning choices and the critical role of the diaphragm within the cane that limits necrosis and desiccation to maintain healthy vascular tissue and sap flow when pruning wounds are correctly managed. The authors also emphasised the importance of applying the proper technique from the beginning of the vine’s training process and not only at the beginning of maintenance pruning.
Reference
Bruez, E., Cholet, C., Coll, P., Boisseau, M., Weingartner, S., Poitou, X., … Geny-Denis, L. (2024). Importance of quality maintenance pruning for young Ugni blanc grapevines. OENO One, 58(3). https://doi.org/10.20870/oeno-one.2024.58.3.8101
Image: Francois Viljoen
