1.4.3.c Examples of the thought-process

Bordeaux Case Study: main rationale

This example concerns the Bordeaux region, but an equivalent line of reasoning can be applied to all regions.

To select only the rootstocks of interest, the following reasoning is applied:

Eliminate rootstalks for which we lack information, specifically regarding drought, humidity or limestone resistance. The same applies to the type of suitable soil. (Example: 216-3Cl)
Eliminate those that are intended for large production volumes (e.g. RSB1 is better for the production of Cognac base wine) or that are too vigorous (Vialla, SO4)
Eliminate those with compatibility problems (41B can be used on clay-limestone soil but is incompatible with Merlot...) or that go into an unexplained decline (161-49C)
Eliminate extreme cases that do not exist in Pauillac (140 Ru)
Eliminate 196-17 from planting because it is too vigorous, but keep it as an option for selective replanting
There are only 8 possible rootstocks left in Pauillac: Riparia, 101-14 Mgt, 3309C, Rupestris du Lot, 110R, 420A, Fercal, Gravesac
Rupestris du Lot and 110R have relatively similar characteristics. The 110R works very well with Cabernet Sauvignon, it should be kept as a possibility. There are 7 remaining rootstocks to detail.

Varietal	Resistance to active limestone in %	CPI	Drought resistance	Moisture resistance	Conferred vigor	Precociousness	Adapted soil type,,,
Riparia Gloire de Montpellier	6	5	Very sensitive	Resistant	Very low	Early	Alrich, non-calcareous soils. Avoid soils that are too clay based and compact. To be planted with good drainage. To be planted in deep gravel, with good drainage. Avoid poor, dry and superficial soil types. ,Well watered. Avoid poor soils that are dry and shallow.
101-14 MGt	9	10	Sensitive	Resistant	Low	Early	Clay soils with little or no limestone. Deep soils with good water supply. ,,,
Gravesac	11	25	Average	Resistant	Strong if plenty of water.		Boulbènes soils, sandy or sandy gravel soils,,
3309 C	11	10	Sensitive	Sensitive	Weak	Early to normal	Good behavior in acidic soils. Well suited to deep, silty-clay soils,lime content, little or none
110 R	17	30	Very resistant	Very resistant	Strong	Late	Best suited to dry , poor soils,rocky,with little or no lime content
420 A	20	40	Average	Very sensitive	Weak	Late	Fertile, fairly deep clay-limestone soils with ,adequate water supply
Fercal	45	120	Intermediate	Average	Strong	Average	All soil-types, especially if calcareous, clay-limestone,and deeper soil constructions.

The Fercal and 110 R rootstocks are to be used in extreme cases (respectively, a very calcareous soil or a very dry, poor soil), otherwise their vigour is too great.
This leaves us with 5 remaining "classic" rootstocks. Riparia Gloire de Montpellier, 101-14Mgt, 3309C, Gravesac and 420A.

In practice:

Riparia and 101-14 can be used anywhere as long as the soil is not too dry or too calcareous.
In sand or silt based soils, 3309C is recommended. On very draining gravels, Gravelac can be used.
The 420A works best in well-buffered clay plots that are not redoxic or reductive (without excess water).
On redoxic or hydromorphic soils, avoid Gravesac. It is best to choose Riparia.

The thought-process at Château Grillet

At Château Grillet, the vineyard’s soils are mainly sandy and superficial. Drought resistance is therefore an essential argument when choosing rootstocks.

For many years, 3309C was used for selective replanting, but it is not sturdy enough to grow easily.

Nowadays, Rupestris du Lot and 110R are mainly used. Their resistance to drought and their vigour allow for sufficient vegetative growth to produce quality wines.

The 140 R will also be tested on excessively pebbly plots that have a very shallow soil horizon (less than 40 cm).

The thought-process at Domaine d'Eugénie

Replanting is rare due to the extreme fragmentation of the appellations. A complete uprooting would directly cause the absence of production for several years.

Traditionally, the plots are planted with 161-49C which is a high-quality rootstock. However, there are two problems with this rootstock today.
The major issue is its tendancy to develop thyllosis (a disorder of physiological or pathological origin that blocks the xylem vessels when the thylle is being developed). This phenomenon causes the vines to decline. Several factors can influence this condition so its emergence is not inevitable. For example, a good water supply and potassium supply can limit its occurrence. Similarly, moderate yields in the first years of production are key to avoiding thyllosis.

The second problem relating to this rootstock, which whilst less problematic is certainly not negligible, is that 161-49 C confers its early-ripening qualities to the graft. In the context of global warming, such a trait makes it a less-than-perfect candidate even if its other characteristics are excellent. It is therefore still used at Clos de Tart on certain of the vineyard’s plots.

On sufficiently-buffered soils with adequate draining, it is best to use rootstalk type 420 A, which slightly delays ripening and absorbs very little potassium, which is key to limiting, even if only slightly, a rise in pH.

When the estate selectively replants, 5C is regularly used because it is more vigorous and allows for better establishment in a very competitive environment. The Estate's current policy of reducing tillage practices brings to light issues regarding water competition. Furthermore, the development of agroforestry also raises additional questions when choosing rootstocks planted near trees.

As a result, more vigorous rootstocks are being considered when planting, such as 333 EM in cases where the surrounding environment drains easily or when there are trees in close proximity (less than 3 metres).
The 41 B seems to be an interesting option except if there is Grapevine fanleaf contamination on the plot because this rootstock is vulnerable to nematodes.
This subject is still very much open to reflection at the moment. Projects such as Root Bourgogne or Greffadapt, which study different rootstocks, are underway to define the potential list of rootstocks adapted to Burgundy.

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