GRAD® 41B Rootstock

GRAD® 41B Clone 1, High Active Limestone -Adapted Rootstock, in brief:

• Selected, after lengthy nursery trials, from an original GRAD® import in the early 2000s. The GRAD® 1 clone is the most robust and hardy of the G1 offspring of the single imported vine that was released ex-quarantine.
• The GRAD® 1 clone is the only source of 41B available in New Zealand.
• This rootstock resists as much as 40% active limestone in soils without such high levels of ionised Calcium inducing chlorosis in its scions. 41B is the classic rootstock of Champagne, and the Charente, but it is also used widely in Burgundy and in many other regions where very chalky soils are present. In these conditions it has a very long and respected history of use throughout Europe.
• 41B is a very good choice as a rootstock for warmer or mildy-warmer sites (Hawkes Bay limestone areas being a clear case in point) or in areas with reliable longer autumns. It has an extended phenological cycle and tends to preserve acidity in its scions’ fruit, as well as continuing ripening well into autumn. It is also the No.1 classic rootstock for use on ‘Champagne’ varieties (Pinots and Chardonnay) in cool-climate vineyards with very chalky soils.
• The GRAD® 1 clone of 41B is a proven ultra-high-health clonal line: it has tested free of detectable virus by multiple PCR tests. All mothervines vines at Stanmore Farm have tested negative for GLRaV3 as per the New Zealand Grafted Grapevine Standard.
• Despite unfounded claims and fears to the contrary, 41B has proven for well over a century now to be phylloxera resistant, with some 80,000 hectares of vines grafted to 41B planted currently in France alone. These plantings extend throughout Champagne, Burgundy, Franche-Comté, Midi-Pyrénées, Val de Loire, Aquitaine, Charentes, Provence-Alpes-Côte d’Azur, Languedoc-Roussillon, and the Rhône-Alpes. (See the 41B web-page on the official French industry website Plantgrape: https://plantgrape.plantnet-project.org/en/porte-greffe/41%20B%20Millardet%20et%20de%20Grasset ). Unsurprisingly therefore, I can find no peer-reviewed scientific papers which demonstrate that 41B is dangerously susceptible to phylloxera. Just as unsurprisingly, the official French industry Plantgrape website says “41 B MGt is highly tolerant to the gall form of phylloxera”. That is why there are so many vines grafted to it throughout France, with many many more in Italy, Greece, Bulgaria, and throughout numerous other European wine-growing countries and regions: it is a proven phylloxera-resistant stock.
• Vines grafted with GRAD® 41B rootstock are available in New Zealand through Stanmore Farm nursery under license from GRAD®.
• E-mail for orders or inquires: orders@stanmorefarm.co.nz
  Phone: 0800 Stanmore (0800 782 666)
  Website: stanmorefarm.co.nz
• Mobile: 027 544 0140
• A comprehensive non-propagation contract must be signed off as part of your purchase of this vine material.
• Download 1 page PDF Fact Sheet on GRAD® 41B

 

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Source

In the early 200os there was a lot of interest, particularly in North Canterbury, in planting on soils that are high in active limestone. Indeed, some of the vineyard soils in these regions are essentially solid chalky limestone that has been broken up as best can be done to allow planting of vines. At this same time I had also held out hopes that the very largely ill-advised plantings in the Waitaki Valley, in frost-drains on low river bed terraces and valley floors, that occurred in the mid- to late-2000s, would be replaced in due course by much better-sited plantings. I particularly hoped  (as I still do) that someone would recognise the huge potential of the very substantial north-facing hillside areas along the Waitaki south bank for growing Pinot noir and Pinot Meunier, as well as Chardonnay, for super-premium méthode champenoise production. With these things in mind, and having found Fercal a less than entirely satisfactory stock to manage when I planted into very chalky subsoils (and, in places, solid limestone) at the ultimately ill-fated Mountford ‘Horehound’ block in Waipara, I decided in the mid-2000s to import the classic chalky soil rootstock: 41B.

 

 

Health status

The GRAD® 1 clone of 41B was obtained overseas from an extensively PCR-tested high health source, and since its arrival in New Zealand it has been PCR tested a further three times and has consistently proved to be free of detectable virus. In addition, all the GRAD® 1 clone 41B mothervines vines at Stanmore Farm have tested negative for GLRaV3 as per the New Zealand Grafted Grapevine Standard.

 

Characteristics

The GRAD® 1 clone 41B is a relatively strong grower in rich calcareous soils, although ultimately it is a rootstock of moderate vigour (comparable to that of C. 3309), especially as it is fairly easily restricted by careful managed deficit irrigation. In warm springs its scions can tend to bud out relatively early, but at the other end of the season, in autumn, its V. cinerea (var. helleri) genes call the shots. Thus so long as there is sufficient autumnal warmth it will keep going, and keep its scions ripening their fruit, well into May.

Rooting in 41B is moderately deep, with a modest number of strong thick spreading roots dominating the root system. I would strongly advise therefore that this stock be planted in deep-ripped soils: it thrives by being able to get its roots well down into the (damp) subsoil / sub-rock. Moreover, as even my intensively selected GRAD® 1 clone is only moderately drought resistant, ensuring good deep root establishment significantly helps 41B insure against declining upper-level soil moisture. Heavier soils and porous chalky limestone are the way to go: avoid planting 41B in fast-draining sandy and stony soils that have low clay / loess content and which do not have reliable moderate water-retaining characteristics. (In such drier conditions, close-planted GRAD® 420A is a much better choice, provided it its well fed in its first five years or so to encourage a strong root system.)

Overall, in well broken up chalk, limestone, and other calcareous soils that are not fast-drying and / or shallow, 41B is a very good choice, especially in areas where there is ongoing autumn warmth (although this latter factor is relatively unimportant of course if it is used as a rootstock for methode champenoise scions). Do not expect it to handle long droughts however, and as such you need to have at least moderate irrigation resources to hand for it to be used in your vineyard. With these basic conditions in place however, GRAD® 41B can be used to support vines planted at between 2000 and 5000 per hectare; it is the sub-soil preparation and the presence of moderate soil-water retention (or suitable irrigation) that are the key to its performance.

 

 

 

Qualitative potential

 

As an ultra-high health rootstock (3 x PCR free of detectable virus), GRAD® 41B is capable of supporting a wide range of high health scions. It is of course renown in Europe as a No.1 choice for the Pinots and Chardonnay on highly calcareous soils, although it can also be used with good results on chalky or limestone soils with Bordeaux varieties like Sauvignon blanc, Malbec, Merlot, and especially Carmenere (which, like 41B, needs ongoing back-up irrigation support in dry conditions). In a nutshell though, Clone 1 GRAD® 41B is ideally suited to two key types of vineyards: in marginal cool areas (like the Waitaki especially), it is an outstanding choice as a rootstock for methode champenoise scions; elsewhere, it is best used in warm cool climate sites or even better still in areas from Marlborough north through inland Hawkes Bay. In this latter area, it has huge potential provided the local limestone is broken up to a suitable depth. Indeed, I would particularly draw attention to the fact that long moderately warm Hawkes Bay autumn conditions should see 41B prove to be an outstanding rootstock to use for Sauvignon blanc (and / or Semillon) as it will allow extended fruit ripening without inducing fast decline in fruit acidity.

 

 

 

Ripening period

Mid-period (although highly effective of course for the Pinots and Chardonnay in the very cool conditions of Champagne). Beyond use for methode champenoise scions, this is a stock that enables extended ripening time in moderately warm to mild autumns. Bordeaux varieties, give or take Cabernet Sauvignon (which is very drought tolerant) are well suited to the ripening cycle and general phenology supported by 41B.

 

Availability

Stanmore Farm Nursery  has good volumes of Clone 1 GRAD® 41B available for grafting.

 

 

Vines grafted with GRAD® are available through Stanmore Farm nursery under  license from GRAD^®

• E-mail for orders or inquires: orders@stanmorefarm.co.nz
  Phone: 0800 Stanmore (0800 782 666)
  Website: stanmorefarm.co.nz
• Mobile: 027 544 0140
• A comprehensive non-propagation contract must be signed off as part of your purchase of this vine material.
• For further details and advice on utilisation and suitability for your vineyard, contact Dr. Gerald Atkinson at grapevines@hotmail.co.nz
• A comprehensive non-propagation contract must be signed off as part of your purchase order.
• Grafting orders may be placed now  subject to volumes and availability.

GRAD^® is a New Zealand registered trademark uniquely and exclusively used to identify the vines in the GRAD^® vine collection. Use by unauthorised parties to identify any vine material, or other use for commercial gain, is an infringement of this trademark.

Genetic ‘fingerprinting’ and clonal traceability

Vine pirates BEWARE! It is now possible to genetically fingerprint, uniquely identify, and individually detect grapevine clones using the latest-developed molecular genetic sequencing techniques. See the breakthrough research paper by Michael J. Roach et al, “Population Sequencing Reveals Clonal Diversity and Ancestral Inbreeding in the Grapevine Cultivar Chardonnay”, published November 20, 2018 at
https://doi.org/10.1371/journal.pgen.1007807

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