01438 741177         thewinesociety.com

The Society's Community

How deep must sand be to grow vines on their own roots?

How deep does sand have to be to defeat phylloxera in order to grow vines on their own roots?

Something I’ve been thinking about since seeing Joel Peterson (Zinfandel master, founder of Ravenswood, owner of Once & Future) speaking about Oakley Road Vineyard.

This is a Zinfandel vineyard planted on its own roots more than 100 years ago. The surface of the vineyard is sand washed down from Gold Rush mining and deposited by flooding of the Sacramental River.

Thus it’s a layer of sand on soil, and presumably roots find sustenance and water from soil below the sand.

So, if a vineyard wanted to plant own-rooted vines and dug a trench filled with sand along the line of where the vines were to be planted, how deep and wide would the sand trench have to be to protect vine roots from phylloxera?

See Joel Peterson talk about Oakley Road vineyard 34-38 minutes into the TWS recording of last week’s talk here

3 Likes

Interesting. The Bas-armagnac region in SW France was not badly affected by phylloxéra for the same reason. My understanding is that the larvae of the insect burrows underground to feed from the roots. In very sandy soil the burrows collapse, hindering the propagation of the weevil. I am not sure if this is at a macroscopic or microscopic level, in other words would a vine be protected if its own roots are surrounded by a few centimetres of sand, or does the sandy area prevent spreading many metres underground to infest the whole vineyard?
I think the idea of digging trenches to protect the vines is risky, over time vines produce very deep roots in search of water. In a well draining sandy trench I suspect they will quickly reach out to the subsoil. The phylloxera larvae do not kill the plant by eating its roots, but introduce a chemical pathogen which kills it over time.
What is the desire to plant vines on their own roots?

1 Like

That said, phylloxera seems a minor problem nowadays. Around here when the odd vine is lost one can replace it taking a mere porteur from an adjacent plant, thus growing off its own rootstock. These don’t seem any more vulnerable than standard vines on American rootstock.
Planting a whole vineyard would be quite risky though.

1 Like

Depending on your level of interest, it may be worthwhile emailing Producteurs Plaimont. They do a phenomenal amount of research into old vines/vineyards.

http://slotovino.blogspot.com/2014/01/the-pedebernade-vineyard-at.html

Thanks for the reply, Steve

Mine is a theoretical question. There are many reason for farmers to plant on rootstocks, for instance, they can choose a rootstock to suit the soil conditions, as do apple farmers and indeed we home growers of tomatoes and peppers can buy grafted plants.

You say that vines will reach the soil under the soil; I mention that in my post; surely sand alone doesn’t hold enough water or have nutrients to support vines. There are several sandy regions in the world which have escaped phylloxera, but how deep is their sand, don’t the vines roots penetrate down below the sand?

My question is how deep does the sand need to be and how far out from the trunk must it be.

As I understand it, the phylloxera louse hatches from the vine leaf, drops to the floor and burrows down to the root.

Why plant on own roots? Joel mentions some benefits in his talk on Oakley Road. The resulting grapes are an expression of the variety and terroir without the third factor of rootstock.

2 Likes

Apparently the cracks that appear in drying clay soils also aid the spread of the mite (as I recall from the book) as they can easily spread through the whole vineyard quickly, so I’m not sure trenches adds any inherent benefit.

They say theres a different taste to the wines on own rootstocks, but according to one winemaker I quizzed on this, he claims it’s all a gimmick. But then he doesn’t have prephylorexic vines to sell.

It’s not the trenches, it’s the sand.

Phllyoxera spreads quickly through a vineyard in any condition except when its flooded. The issue is protecting the roots. Sand provides protection, otherwise American rootstocks.

I understand the concept you’ve floated, but I think the constituent parts of the majority of the soil make-up in the vineyard would probably be the issue.

Its spreads quickly and devastates quickly. It can’t spread quickly in sandy soil (the why bit I don’t know), but can in clay soils, so, if I recall the science from the book, because of it’s complicated life-cycle (up to 20 different possibilities isn’t?) it needs to reproduce and move on quickly, as it effectively destroys its own hosts, needing new hosts all the time. I don’t think sandy soils kill it as such, just slow the process. A bit like the ‘social distancing’ we’re all undergoing now.

But wouldn’t you agree that if the sand at Oakley Road has allowed vines to live for more than 100 years on their own roots then it does more than ‘slow the process’?

Unfortunately, the science is far from conclusive - there just hasn’t been enough research into the ‘why’ part of sandy soils (as I understand it) because, once the planting of American root-stock started and was found to work, research dwindled away, because it was deemed unnecessary.

As far as I understand it, some vineyards with sandy soils and mixed soils didn’t survive, only a tiny fraction of vineyards that were sandy survived. Coincidentally, they all have sandy soils, but it isn’t the panacea that it is presented as, as some vineyards with sandy soils din’t. The only reasonable stab at an explanation I’ve heard is that they were ‘inner-sanctum’ vineyards. So sandy soil, surrounded by hectares of sandy soil. But, AFAIU, it’s just a theory, because no-one seems to know conclusively.

1 Like

Like so much else in the world of wine :grinning:

3 Likes

… Coincidentally, they all have sandy soils, …

Maybe not the whole answer, but seems a bit unlikely to be a coincidence. Not that I have any enlightenment to offer.

The most interesting wine related to being grown in sand is the remarkable Colares from the coast of Portugal near Sintra. Less than 50 acres remain, but the wine produced is worth trying to get hold of. Because of the wind and proximity to the sea, the vines are planted in trenches up to 4 metres deep and as the vines grow, they are topped up with sand. No grafting has ever been done, and in the 19th century, there was no phylloxera, asa it is claimed the insects can not live in sand. Vines grow very much horizontal to the ground with branches held up by short wooden pegs. One vine may cover an area of 16 sq metres. Virtually all the Colares wine (largely red, from the ramisco grape, which is not found anywhere else) is produced by the Adega Regional de Colares cooperative. The wine is sold in 50cl bottles. It is worth finding!!

Indeed, but not all sandy soils provide complete protection against Phylloxera.

And therein lies the problem. How do you prove which sandy soils will provide the protection against such a devastating pest - especially when you’re about to sink a large chunk of investment into vulnerable vines?

For many years I have enjoyed the Listel wines produced in the Camargue by the Salins du Midi company.
I understand that they are possibly the largest planting of ungrafted vines in the world and they survive because of the sand.

Volcanic soils often also seem to be resistant.

Look no further. Its rather pricey, especially for 50cl - but worth it.

2 Likes

Maybe the largest in France, but the whole of Chile is phylloxera free and vines there are ungrafted.

Until recently the South Island of New Zealand was phylloxera free, and there are many older ungrafted plantings there. I visited one vineyard where footwear had to be scrubbed to clean off any possible phylloxera.

1 Like

Casa mia the sand seems infinitely deep, I dug 2metre deep trenches for some geothermal pipes and it was all sand. Even in late August the sand was moist from 40cm down so I don’t think moisture retention is an issue. Where I planted the vineyard it was very rich loamy soil on the surface (by accident, not design).
As for the rootstock affecting the flavour of the wine? Hmm. As another poster mentions this could be marketing. A great number of things affect the eventual taste of the wine, but one never hears of a differentiation based on the different rootstocks in use…

1 Like

Better still St Mont has a wine festival in March every year (usually) well worth going to have a look yourself!