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Marcottage in Margaux

Last year I wrote on the practice of provignage at Domaine de la Bergerie. In a quick two or three sentence recap, provignage is an ancient method of propagating plants, including vines, obviously. A branch or runner is pinned under the soil (with a peg of some sort, or simply by placing a rock over it), after which it will put out new roots, and by cutting the runner/branch joining this new growth to the parent plant – hey presto! – you have a new plant. For free. It was, naturally, an excellent way for peasant vignerons to propagate new vinestock for their vineyard (there’s more detail in the post linked above if the above isn’t clear).

And then along came phylloxera. And now, if you believe the books, vines in France and other infested regions of Europe must be established on grafted phylloxera-rootstock if they are to survive. Either that, or planted on certain phylloxera-unfriendly sandy soils.

Which is why the vines at Domaine de la Bergerie were of such interest to me. They had been propagated using provignage many decades before, and seemed to be thriving, despite living on their own roots in a damp clay soils, just perfect for phylloxera. Proprietor Yves Guégniard didn’t seem to know why or how they survived, but I suspected it was something to do with the fact that in every case the original runner connecting the new plant to its parent had not been cut.

Marcottage in Margaux

I haven’t thought much about it since until, late last year, at Château Boyd-Cantenac in Margaux, there before my eyes were yet more vines propagated in the same manner. The picture above shows the runner, about as thick as my thumb (and so nowhere near as old and crusty as Guégniard’s vines) which originates with the parent (on the right) and dives beneath the surface towards the roots of the offspring plant (on the left). Here, however, owner Lucien Guillemet referred to this practice not as provignage but as marcottage. Having read around, I can see no difference between the two practices; I had thought it might refer to whether the runner is cut or not, but it seems not. Descriptions of the two are identical; I would be delighted if any viticulturists or plant scientists out there want to chip in with an explanation of how they are different, if indeed that’s the case.

I asked Lucien what would happen if the runner were cut, and he was quite certain in his response; the offspring plant will die. This clearly indicates it is reliant on its parent for support, and so my initial suspicions were correct. Its own (no doubt phylloxera-infested) roots are not enough to maintain vitality, but with the help of its parent’s American rootstock it survives. Does any nutrition come from the infected root system at all, I wonder? Is the plant entirely dependent on its parent for life, or is it more of a crutch? And if dependent, is it really a separate vine, and not merely a branch? Should this be taken into consideration when looking at planting density, numbers of buds and bunches, and yields?

Biodynamics and Yeast Biodiversity

Does biodynamic viticulture really make a difference to the vineyard? Over the years I’ve asked this question of several vignerons who have undergone the conversion from organic to biodynamic methods and comments on the apparently increased health of the vines have been common. Reports included more vigorous growth, deeper greener colours, thicker stems and so on (one such report came from Eddy Oosterlinck of Domaine de Juchepie, pictured below); how valid these observations are, made in unblinded fashion, comparing the current season’s growth with the memory of the previous year’s, however, is certainly open to question. And what about the microbial life? It’s easy to look at the rich, grassy and floral carpets seen in the organic or biodynamic vineyard and imagine that the soils are full of healthy and happy organisms, especially when they are compared with the scorched-earth vineyards of some chemically-managed estates. Orange grass never inspires confidence, does it? But is there any evidence to support a conclusion that one vineyard really is more ‘healthy’ than another?

Biodynamics and Yeast Biodiversity

Well, I can’t say I’m particularly well read in this area, but a recent paper published in PLOS ONE, from Setati et al at the Stellenbosch Institute for Wine Biotechnology, seems to throw some light on the matter. Methodologically, it looks like a sound study, although I would suggest that such judgements are really only valid coming from someone with a knowledge of the literature; this knowledge allows you to look at a paper with a more critical eye, rather than just believing, which is a common problem when journalists read research papers I find. With my lack of credentials firmly established and accepted, I still think this is a valid and interesting paper (link at the bottom of the page).

The study involved three vineyards, managed in three fashions: (1) biodynamic, (2) conventional and (3) integrated production. Vineyards (1) and (2) were managed as you would expect, whereas vineyard (3) was a sort of ‘half-way house’ site, where some chemicals were used, but alongside some less conventional methods including cover crops, chicken manure and soil inoculation. Samples of grapes from the three sites were taken to see how the microbial flora living on the fruit differed across the three sites. Samples were taken from numerous spots within each vineyard, and they were analysed using not just cultural methods (i.e. seeing which yeasts and other organisms grew when washings from the samples were plated out on suitable growth media) but also using molecular techniques. These fancy molecular techniques looked at the DNA (well, RNA to be pedantic, but that’s not important right now, and you get the idea) of the ribosome, a structure which not only allows typing of the organism but also allows you to see how closely a group of said organisms are related.

The results were interesting on many levels. Before coming to the biodynamic differences, the authors pointed out that (a) there was some variation within vineyards, from one row to the next, and (b) the modern molecular methods identified more species than the older cultural methods. Both findings are relevant to researchers in the area as it means (a) previous studies where sampling has been limited may be flawed because of the small sampling technique – you need to examine multiple spots within each vineyard to get a true picture, and (b) older studies using cultural and not molecular methods will have presented only a partial picture of the organisms living in the field of study.

These findings are important, but it is the biodynamic differences the team identified that were the most interesting part of the results I think. Firstly, there was certainly more diversity in the organisms identified in the biodynamic vineyard. As an example, one species – Aureobasidium – accounted for 70% of all isolates in the conventional site, 63% in the integrated site, but only 53% in the biodynamic site. Many organisms were only seen in the biodynamic site; admittedly many were seen in the conventional/integrated sites and were not in the biodynamic site, so this doesn’t really prove anything, it is more the overall diversity that is of interest.

Some species identified, such as Sporisorium, which was in the biodynamic vineyard but not the others, have never been picked up in vineyards before; this at first glance seems heart-warming, but we must bear in mind that the new molecular methods might be responsible rather than this being a result of biodynamics. Of greater interest, though, is the fact that several species identified in the biodynamic vineyard but not in the other two are of potential benefit to the vines. Meira geulakonigii and Rhodosporidium diobovatum, both living in the biodynamic vineyard studied, have active biocontrol capabilities. Meira geulakonigii is active against spider mite and rust mite, with the mites suffering 100% mortality when exposed, whereas Rhodosporidium diobovatum is active against Botrytis cinerea, which might be famous and welcome for its effect in Sauternes but in most vineyards would be regarded as a pest, causing harmful grey rot.

Clearly the study only reveals the tip of the iceberg, and there is huge scope for further work here. Nevertheless, even taken in isolation, this study seems important; biodynamics improves microbial diversity, and these more diverse species may be active against pests and rot, and thus be of benefit to the vine. None of this necessarily translates through to increased quality in the final wine though; I suspect research in that area will be fraught with confounding variables (although there should be no shortage of willing test subjects!).

Link to the paper: The Vineyard Yeast Microbiome, a Mixed Model Microbial Map

Provignage at Domaine de la Bergerie

I’ve written about the old practice of provignage – gardeners may know it better as ‘tip-layering’ – before (it’s hard not to with wines such as Provignage, from Henry Marionnet). Well, in truth, there is more to provignage than there is to tip-layering, with many variations on the theme. The technique in Burgundy, for instance, often involved excavating soil and then burying the entire vine with only the growth tips showing, a little more drastic than merely layering a shoot. But the basic principles behind these techniques are the same. When used as a straightforward method of propagation, the new vine is generated by securing the growing tip of a pre-existing vine beneath the surface of the soil. The tip will form roots, and once established the newly-rooted plant can be separated from its genetically identical parent with a swift cut of the knife. The result is one healthy (provided the parent was healthy, of course) young vine, on its own roots. These days, however, because vines on their own roots are vulnerable to attack by phylloxera, propagation using this technique is rare. Nevertheless it was once very common, and it was a good method by which a peasant vigneron could expand his vineyard and thus enhance his income.

This week and next I am reporting on a series of tastings at La Table de la Bergerie, featuring not only the wines of Yves Guégniard but also Claude Papin and Vincent Ogereau. But before the tasting began we took a walk among one of Yves’ older vineyards, next to his house and cellars. I found what I saw there to be fascinating; first, some of the vines there had been propagated by provignage, and were thereby planted on their own roots, and yet – looking at the thickness of the vines themselves – they had seemingly been thriving for many decades. That in itself seems unusual, in a region where ungrafted vines (such as those planted by Pithon-Paillé on the Coteau des Treilles) quickly succumb. But, in addition, these provins (as they are known) were still attached to their parent plant by the original shoot, now thickened with age. I had naively thought this would be severed once the plant had rooted.

I had time to shoot a quick video of the vines in question. It is less than half a minute long, so don’t blink:

I found myself with two questions. First, why not sever the provin from the parent? Second, could the apparent phylloxera resistance of the provins, and this lifelong connection between parent and offspring, be in any way related?

Dealing with the first of these two questions requires a little knowledge of history, and how viticulture today differs from what was carried out in the past. The concept of a vineyard full of distinct, individual, neatly arranged plants is a modern necessity, brought about by (a) increased use of horses and then vehicles in the vineyards through the 19th and 20th centuries, requiring planting in neat rows, and (b) the need for vines to be each planted on their own phylloxera-resistant roots. Prior to these two major changes vineyards were not collections of many individual plants, but a heterogenous, amorphous mix of vines and roots, interconnected and densely planted (a side effect of provignage – the shoots only reach so far from the parent vine, so vines were propagated close to one another). New vines were established by layering the pre-existing vines in one direction. As such vineyards tended to ‘migrate’ along the ground, eventually new vines would have to be taken to the now barren end of the vineyard to replant there.

ProvignageThere are a few such vineyards still in exstence today, of which perhaps the most famous belong to Bollinger, and are the source of the Vieilles Vignes Françaises cuvée. One of these is the Chaudes Terres vineyard, behind the Bollinger headquarters in Aÿ (shown right). The pictured vines are not individual plants but stem from a network of underground roots; the soil (as can be seen in the picture) is sandy, and this has deterred the phylloxera from attacking. As the old-timers noted, the vineyard ‘migrates’ (in this case, up the slope) and every few years fresh vines are planted at the bottom to maintain production. It sounds ridiculous, but this system – with the vineyard planted en foule, a mix of tightly-packed, randomly-positioned vines – was once the norm.

So, with memories of an era when vineyards were very different to how we see them today, it is of no surprise that the provins were left attached. What benefit would there be, after all, to their separation? The whole vineyard used to be like this, why worry about a handful of vines? The vigneron of fifty years ago would have regarded it as unnecessary work. Or perhaps they knew better to separate the vines? Perhaps they saw that provins separated from their parents did not thrive so well? I’m hypothesising wildly here, by the way.

And this brings us to my second question; how have such vines survived in a phylloxera-infested environment? Is it just chance? That seems unlikely. Or is it that, despite having their own phylloxera-susceptible roots, they receive sufficient nourishment from the parent plants (which were grafted vines), in order to remain healthy? Unfortunately, a trawl through what is written on provignage did not yield many clues; the literature does not seem extensive, especially literature concerning provignage in the post-phylloxera era. I don’t have an answer to this question, but here are a few interesting points I picked up along the way.

In his Treatise on the Vine (T. & J. Swords. and other publishers, 1830), William Robert Prince wrote the following of provignage: “…in vineyards where this course is practised, new vines are not required, for there, as is the case in Burgundy, the provins not being separated from the parent vines, the plants can be preserved for centuries, which is favourable to the quality of the wine“. Prince was an American, concerned mainly with phylloxera-resistant American vines, and he was writing before the disease had swept across Europe (before the disease was even known of, or understood), so naturally he makes no mention of phylloxera resistance of the ungrafted vines. Nevertheless he seems to have noted some qualitative advantages of leaving the provin attached, implying that the attached vines are certainly different to those that are separated. Healthier? More disease resistant? Prince doesn’t say.

More recent (and we would have hoped more relevant) references to provignage do not provide any clues; describing the process in Viticulture: An Introduction to Commercial Grape Growing for Wine Production (Lulu, 2007), Stephen Skelton writes of the provin, “[t]his shoot can then be trained up a support and in due course the new vine can be separated from its neighbour and – voila – the empty space has been filled“. There is no suggestion anywhere that the vines may be left connected, or that this may aid the battle against phylloxera. And I could find no mention elsewhere of whether provignage from grafted vines might be different to provignage from ungrafted vines in terms of how the vines cope with phylloxera.

There were a few other interesting references to provignage I uncovered, from James Busby (also writing in the 1830s, pre-phylloxera again), but not much else new. So ultimately my question remains unanswered. I would be delighted if readers can come up with any thoughts or hypotheses on whether ungrafted vines connected to a grafted vine might survive in a vineyards where phylloxera is endemic, or if you know of any other writings on the subject I should check out.