Hedging and Braiding

This is a hot topic on which I feel completely unqualified to make a post.  But - among high profile Domaines in Burgundy and many prestigious properties elsewhere - in the viticulture space it is very much the topic being discussed.  So it merits a brief post to introduce the subject, accompanied with a strong recommendation to find other more authoritative sources to guide you through the topic in more detail..   

For this particular summary I am indebted in large part to the Wineanorak.com site 

The question relates to canopy management. At issue is what to do with a vine’s long lead shoots and accompanying “excess” foliage that may continue to develop from the top of the vine in the period leading up to and after veraison. The traditional approach is to remove this excess vegetation by cutting it away by hedging clippers installed on a tractor - hedging or “rognage” - with the purpose of getting the vine to focus not on producing additional leaves but on producing and maturing fruit. In the normal course versaison is the time the vine, if in perfect balance, would make this transition of its focus from vegetative growth to fruit development naturally.  But this is seldom the case. Vegetation continues to grow if nutrients are still available. 

The latest idea, however, is that this hedging is harmful to the vine and a process has been developed - initially as I understand it by Domaine Leroy from about 1999 - not to cut the vine at all but to “braid” the excess foliage by folding it in on itself and rolling it together - a term the French call “tressage”.  Alternatively the tips can be strung along the top wire to meet the neighboring vine. This process is terribly expensive. According to Charles Lachaux of Domaine Arnoux-Lachaux in Vosne Romanee, tressage takes perhaps twice the time and four times the number of workers as conventional hedging. Pruning the subsequent winter is also more challenging. 

The reason for braiding the vine is primarily that if you cut the top part of the vine away its natural response is only to produce more lateral shoots to compensate. And lateral shoots are a particular problem because they shade the fruiting zone.  Any home gardener will buy into this rationale.   

But given this widespread adoption globally - from Piedmont to Alsace to the Finger Lakes - as you might expect the list of other benefits asserted by its proponents is long.

One is that the berry bunch forms more loosely if the vine is not hedged because the little rachis stalks to which the berry is attached grow longer, which improves airflow through the bunch and thus reduces the likelihood of rot.  

Other claimed benefits - from growers in Piedmont - are that tressage keeps the pH low in the resulting must and reduces sugar in the grape - though work by David Croix in Burgundy on his Beaune Bressandes vineyard suggest neither acid not sugar are impacted.  He nevertheless endorses the approach because, without necessarily being able to attribute a reason, his empirical tests do result in a favorable difference in the wine that was made from grapes subject to tressage relative to the wine made from vines that were hedged. 

Given the high labor cost of performing the braiding, some are considering simply hedging in the conventional way but doing this as late as possible. 

There are many unknowns here.  In particular what is the role played by the extended foliage and the very tip of the vine ?  From one’s opinion on that flows a view on what you lose if you cut away that tip, which in turn informs whether one is willing to incur the considerable cost of keeping it. 

The picture shows Domaine Leroy vines Romanee St Vivant, taken in December 2016, which illustrates the braiding technique