GRAD® DRC5 Super Rootstock

This new V. cinerea x V. riparia rootstock, which is unique to GRAD, is by some distance the toughest and most hardy cool-climate-adapted rootstock available in New Zealand.

GRAD® DRC5 Super (V. cinerea x V. riparia) rootstock in brief:

  • Unique genetic line of V. cinerea (possibly var. Helleri) x V. riparia from the multiple crosses of these species that generated many of the seeds used by Sigmund Teleki to establish his numerous interspecific hybrid rootstock lines.
  • Formerly mis-identified (as best can be determined) as SO4 and then re-identified by basic DNA testing as 5C, with the latter identity now very much under question as evidence mounts that, overall, ‘5C’ Teleki is a group of (an undetermined number of) ampelographically highly similar hybrids, not just one single hybrid.
  • Discovered by GRAD® in a very large comparative trial of ‘SO4’ and ‘5C’ clonal lines sourced from all over New Zealand including many lines from remnants in old M.A.F. and D.S.I.R. trial blocks and experimental plantings.
  • Distinguished from other SO4 and 5C lines in New Zealand by the combination of its extraordinary robustness and amazing drought tolerance; this is by some distance the toughest and most hardy cool-climate-adapted rootstock available in the country
  • Selected over 7 years of ‘elimination by death’ intensive rootstock trials in the GRAD® R&D nursery, using pot-grown vines which were repeatedly dried right out until defoliated. Schwarzmann did not survive a single season, the best line of Couderc 3309 in New Zealand died out early in the second season, and even the highly drought resistant stocks Richter 110, GRAD® 44-53, and GRAD® 106-8 collapsed in the third season, and were too weakened to continue with in this deliberately brutal extended trial. By comparison, the GRAD® DRC5 Super rootstock not only survived being dried out to total defoliation up to three times in one season, but was the only viable remaining rootstock by the after four years of this trial. Several further seasons of similar treatment also did not lead to this stock failing to recover and grow on in the subsequent season. (GRAD® does not advise treating commercial plantings this brutal manner, of course.)
  • GRAD® DCR5 Super has a powerful root system that shows a high level of V. cinerea inheritance, including lime tolerance, exceptional robustness and power, and of course remarkable drought tolerance and recovery from drought. Give it water and feed it after severe drought, and its powers of recovery are remarkable; this is a very very tough rootstock.
  • This entirely novel genetic line’s characteristics surely makes it the No.1 ‘go to’ industrial rootstock in New Zealand for use in high-cropping cool climate vineyards where drought and / or restricted irrigation supply are a threat to ongoing vineyard viability.
  • Vines grafted with GRAD® DRC5 rootstock will be available exclusively available in New Zealand through Stanmore Farm nursery under license from GRAD®. For details regarding supply in future seasons and for forward orders, contact Stanmore Farm nursery.  Contact
  • A comprehensive non-propagation contract must be signed off as part of your purchase order.

Source and History

It is in fact extremely difficult to definitively  determine the origin and provenance of this unique GRAD® rootstock line. Indeed, it is even far from entirely clear that it is actually anything other than a previously mis-identified Teleki hybrid selection that looks very much like ‘5C’ but which has fundamental genetic variances that make it perform very differently and distinctively in certain key respects. In my opinion, having grown this stock for around 17 years now, it is actually so different in certain aspects of its phenology as to completely beggar the naive view that it could merely be ‘just another clone of 5C’. In addition, it is highly opaque as to what identity this genetic line actually bore when imported to New Zealand or whence it was sourced, although there seems, at least, little doubt that it is a Teleki seedling hybrid out of the increasingly in-question ‘5C’ line. Parallels with the South African -utilised Montpelier / Foex / Richter stock ‘Propsperi Super 99 Richter’ seem far more appropriate in my opinion however, rather than holding to any ongoing references to ‘5C’. For the emerging truth from genetic studies appears to be that ‘5C’ is a stock that is significantly genetically diverse when deeply analysed and compared over a comprehensive range of European-sourced lines. Indeed, this is so much so that a growing number of researchers now consider ‘5C’ to be a group of morphologically indistinguishable but genetically separate, varieties. How many different varieties are in this group is still an open question. As such, the idea that ‘clonal variation’ in vines currently named ‘5C’ can continue to be used as a satisfactory explanation for the huge variability in the behaviour of vines under this name — irrespective of their all looking closely identical by non-genetic ampelographic criteria — is now under serious question, especially by central-European researchers with access to the original Hungarian Teleki pool of vine stock. The proposition is thus very much afoot that ‘5C’ (like the Teleki lines ‘5A’ and 8B’) breaks down into separate hybrid varieties.

Much in the growing debate about this seems to depend upon the range of Teleki-Kober varietal type-specimen material which is D.N.A. sampled. It appears that Hungarian and other central European sources — holding Kober – Teleki selections tracing much more directly and diversely to Teleki’s original selections — show much higher variability and more probability of multiple hybrids being mistaken for mere clones, than is seen in western European and U.S. collections. One is sceptical therefore that lines held in France and California, for instance, and perhaps many in Germany, are capable of being used to decide this issue — because they consist in material sourced from just one or two of the original Teleki visual selections that made up the ‘5C’ line. On the other hand, researchers in Hungary in particular are likely to have a much more diverse range, and it is their wider sampling base of ‘type specimens’ from this, of course, that is throwing up the questions about significant variability in the supposedly settled and single hybrid varietal Teleki 5C line (as well as that of Kober-Teleki 5BB it seems).

In the case of GRAD® DRC5 Super, the picture is further clouded because multiple importations of mixed-up ‘SO4’ and ‘5C’ were made into New Zealand in the 1960s through to the 1980s, including one or more Geisenheim lines and an indeterminate range of U.C.D. lines. Among virtually all of these there are very significant performance variations — especially in vigour and drought resistance — which suggest much deeper genetic variability than mere clonal difference. (The last two SO4 imports to N.Z., from Bordeaux sources, are undoubtedly genuine and are NOT ‘5C’ — viz.: so-called ‘BDX’ and ‘Sica 8’ — but what is little known is that both of these bona fide SO4 clones were were tissue-cultured in quarantine and that what was then released was not the original material but only the N.Z.-made explants derived by tissue culture.) Whether and how far the GRAD® DRC5 Super rootstock derives from any of the numerous 1970s-1980s imported ‘SO4’ / ‘5C’ vines or instead is a further mistakenly identified  imported Teleki line is very much an open question too.

But in addition to these considerations, it must also be taken into account that in the 1970s and into the early 1980s, first D.S.I.R., and then M.A.F., conducted a range of frequently mutagenic regenerations on most, if not all, of the ‘SO4’ / ‘5C’ imports then in N.Z. (which were far from homogeneous in the first place) in an effort to free them from virus infections. Very large numbers of (sometimes highly performance-variant) explants were produced as a result, and I have found vines from these experimental lines growing in numerous sites in both the North and South Island, including in all sorts of odd out of the way plantings, abandoned experimental blocks, and even it seems as merely decorative ground and tree -cover vines! Despite these stocks appearing to be ampelographically identical, and having myself whittled them down by basic DNA testing (at 6 to 12 microsatellite sites) to only those that were so called ‘5C’, examination of their root systems, growth habits, and drought tolerance shows extraordinary phenological variation among them. For a long time I simply followed the accepted science and passed this off as ‘clonal variability’ even though the relevant differences within the 40+ vine range of these selections are huge at the extremes. Now I believe developments in molecular biology and DNA-analytical science have at last begun to offer a far more satisfactory explanation: these are very likely not to be different clones; some of them are ampelographically all-but-identical vines that nevertheless constitute separate hybrid varieties.

It is no surprise to me then than that, for example, in 2009, Hungarian researchers raised serious questions pointing to the likely polygenic / multi-varietal / multi-hybrid constitution of ‘5C’. In particular, Podmaniczky et al published a key paper (“Genetic Differences among Rootstocks Derived from the Teleki’s Seedlings”, in Proceedings of the IXth International Conference on Grape Genetics and Breeding, ed. E. Peterlunger et al.Acta Horticulturae 827, ISHS, (2009)), which, in its introduction, pointed out that “Because of the urgent demand for propagation, canes of individuals assigned to one morphological group” of the Teleki rootstocks “were released in the market under the same name, like 8B or 5A, which are, therefore, not single seed descendants.” (My emphasis.) This is a profound truth about the Teleki rootstocks that, outside Hungary, has implications which in some quite fundamental respects have been long overlooked. In the specific case of 5C, Podmaniczky et al found that “the clones selected in Germany are different from the Hungarian-selected clones. Beside this, independent from the place of selection, different alleles were obtained” by the genetic analysis we conducted “for the same locus, indicating that these putative clones are not identical. [My emphasis.] We hypothesized that either the selection was performed on heterogeneous material collectively identified as ‘Teleki 5C’, or mis-identification occurred in morphological classification during the selection process.” — This is a striking claim by these researchers, and in my opinion the possible explanation in terms of mis-identified type specimens can be dismissed because extensive ampelographic studies of 5C (and its morphological differences compared to other Teleki – Kober rootstocks) have been published for decades now. Perhaps however, because they are genetic researchers, Podmaniczky et al are unaware of this. In any case though, their paper’s conclusion surely connects the fact  that, for example, “different clones of ‘Teleki 5C’ have a different adaptation to calcareous soils and environmental conditions, like drought” with genetic differences which go beyond mere clonal variation.

This fits precisely and exactly with what I have observed for along time now within the numerous lines of ‘5C’ Teleki in New Zealand. While they all look the same from an ampelographic point of view, their performance in vineyards is highly variable. In particular, and especially given my key rootstock development and selection concerns, certain N.Z. ‘5C’ lines’ drought resistance exhibits extraordinary characteristics that set them altogether apart from all the other ‘5C’ lines. It is my contention therefore, and it is also the basis of my offering the GRAD® DRC5 Super rootstock to the market, that the scientific evidence at the genetic level now increasingly strongly shows that these observed differences are due to the fact that ‘5C’ is actually a group of genetically different hybrids that just happen to all look the same. Consequently, and based on this growing body of scientific evidence, I suggest that GRAD® DRC5 Super rootstock is almost certainly a unique rootstock variety: a singular, genetically discriminable hybrid and that it is NOT a mere ‘clone of 5C’.

Further and ongoing peer reviewed scientific research continues to offer support for this view. In their research paper “Analysis of grape rootstocks by SSR markers”, in Journal international des Sciences de la Vigne et du Vin, Vol 45, No 4 (2011), Jahnke et al found strong differences between both the so-called Teleki 5C and Teleki-Kober 5BB ‘clones’ which they studied. They propose that they are not real clones of these two hybrid ‘varieties’ at all, but rather are in fact different genotypes with highly similar morphological features: ampelographically indistinguishable but genetically-distinct different hybrids. Similar results were reported by Poczai et al in their paper “Phylogenetic Analyses of Teleki Grapevine Rootstocks Using Three Chloroplast DNA Markers”, in Plant Molecular Biology Reporter, April 2013, Volume 31, Issue 2. And even in their very recently published attempt at a fairly comprehensive genetic analysis of grapevine rootstocks, Riaz et al, in their paper “Genetic diversity and parentage analysis of grape rootstocks”, in Theoretical and Applied Genetics, published online as https://doi.org/10.1007/s00122-019-03320-5 on March 8th 2019, failed to dispose of these issues and the questions they raise. They used only six dried tissue samples from reference Teleki series rootstocks provided by the Department of Horticulture, University of Pannonia, Hungary. Presumably these were intended to definitively cover Teleki 8B, 5A, 5C, SO4, Kober 5BB, and Kober 125AA from (of course) their original Hungarian source. This seems arguably rather odd however, given that the two above-cited papers both strongly suggest that at ‘Teleki ground zero’ as it were — Hungary — there is by no means any definitive single type specimen of 5C, 5BB, or perhaps even 125AA to be had. In turn, this could well be, per Jahnke et al and Poczai et al, because these Teleki lines are polygenic and thus contain not various clones of one ampelographically-identical variety but instead diverse hybrid varieties that nevertheless cannot be distinguished ampelographically. Given this, the ‘type-specimens’ used by Riaz et al would, ex hypothesi certainly be genuine then, but the assumptions made about their being representative of what Teleki and Kober et al identified (visually of course) as ‘5C’, ‘5BB’, etc. etc., would be erroneous.

In the case of the material which has been introduced to New Zealand as ‘Teleki 5C’ (or re-identified as such), the question I wish to raise is how many of these are in fact different (but nevertheless ampelographically indistinguishable) hybrid varieties passing under one and the same name. For the New Zealand situation as I now very strongly suspect it is, seems very much to parallel what is highly likely to be the case in the home of Teleki stocks, in Hungary (and which has then been carried over at least to collections in other parts of eastern Europe). In neither case can it simply and dogmatically be insisted that ‘the wrong type specimens’ are being used for identification. For there is just too much evidence now that the differences in question are deep, profound, distinct and varietal — and are surely not merely clonal.

There are in any case very clear precedents regarding the division of Teleki stocks from classification as just one hybrid variety to several. It is well known that Teleki 8B has been discriminated so far into five distinct cultivars, which have then been broken down further in Germany (Durlach 50, 51, 52), Italy (Ferrari, Cosmo 2, and Cosmo 10), and Romania (Dragasani 37, 57). Teleki 5A would appear also to fit this bill, and obviously enough ‘5C’ and ‘Kober 5BB’ are now seriously in question, with some evidence also suggesting that even ‘125AA’ may be more than just clonally variable. Only SO4, of the major Teleki – Kober stocks seems at present to be out of the woods and not in doubt as perhaps being polygenic to the point of being a group of hybrids rather than one single hybrid variety.

To summarise however, whatever the GRAD® DRC5 Super is  — an extraordinarily different clone of 5C or a separate hybrid variety (out of an unknown number of such hybrids) that merely looks identical to ‘5C’ — it is in either case an exceptional and unique rootstock. There is nothing else like it among all the rootstocks currently available in New Zealand: it is the toughest, hardiest, and most drought resistant.

 

Health status

GRAD® DRC5 Super rootstock is free of detectable virus by multiple PCR tests. The mothervines at Stanmore farm are also free of GLRaV1,2,3, and GVA by subsequent multiple E.L.I.S.A. tests.

 

Characteristics

If we take as a starting point the widely grown ‘5C’ type that is usually identified in New Zealand as Geisenheim 6-4-28 (or otherwise Gm 6-4), and include with it the ultra high-health N.Z.G.V.I.G. clonal line derived from this as well, moderate vigour and relatively low tolerance of drought are notable features. By comparison, GRAD® DRC5 Super rootstock is massively different in its performance: it is a very strong grower and it is of course extraordinarily drought resistant. Thus the Gm line stands at one extreme of the apparent spectrum of putative ‘5C’ stocks in New Zealand, while GRAD® DRC5 Super is absolutely at the other end. In between are an indeterminate range of mostly ex-U.C.D. ‘5C’ lines that are a lucky (or not so lucky)-dip of characteristics falling between those of the Gm line and those of the GRAD® genetic line. Indeed, other than by specifically ordering the Gm 6-4 (-29) line or the GRAD® DRC5 Super rootstock, you have absolutely no way of being sure of what will be the real characteristics of the ‘5C’ rootstock you are supposed to be getting for your vineyard.

GRAD® DRC5 Super rootstock was specifically selected and developed to offer significantly reduced vulnerability to these increasingly more imposing factors in managing high-cropping vineyards, and particularly (although by no means exclusively) in the now huge vineyard areas of Marlborough’s poor stony soils and heavy sodic clays. As available irrigation water becomes inevitably more scarce and  more often and more intensively, rationed this issue cannot be ignored. The days of easy season-long irrigation in copious volumes in vineyards using rootstocks that have little or no drought resistance (especially when supporting scions bearing at 15 – 20+ tonnes / ha) are fast coming to an end. 

“There are too many over-irrigated vines in Marlborough, which I can’t understand” — Richard Smart

— as reported by Tessa Nicholson, Winepress, March 2013.

 

Qualitative potential

I chose to focus on developing GRAD® DRC5 Super because it was obvious to me as the first decade of the 2000s unfolded that not only were most New Zealand vineyards planted on the wrong (weak and water-demanding) rootstocks, but also that significant reductions in annual rainfall and major restrictions on irrigation were on the horizon for at least the east coast of both islands of N.Z.  These conditions and circumstances are now fast becoming the new normal, and we have by no means seen the worst or the harshest of them.

It is a total and utter lottery therefore in New Zealand, outside of these two very different rootstocks, as to how, and how well, any ‘5C’ rootstock grafted to your scion selection is going to perform — or fail to perform — in any given planting anywhere. Moreover, with some New Zealand now nurseries offering a ‘5C mass selection’, the lottery has become outright: within rows of vines grafted on this m/s range it is conceivable that ripening, crop levels, vigour, root system size and depth, and drought resistance will potentially vary enormously. This will be so because (if these are genuine mass selections) there is absolutely no consistency within such random bulk-selected lines of ‘5C’ in New Zealand. Certainly, I have seen established stands of vines in Marlborough on ‘unknown’ lines of ‘5C’ that perform well, but I have also just as many others that are either a mixed bag of strong, intermediate and weak vines or which are almost all at the weak end of the spectrum and are often very water and nutrient demanding.

These are circumstances — widely found I suspect — under which it is extremely difficult, if not impossible, to secure consistent vine performance and management, and in my experience the sharp end of this is increasingly proving to be found when vineyards are faced with prolonged periods of significant water deficit. At that point what line of ‘5C’ you have is a matter of huge significance. In Marlborough for example, the Regional Council now appears to be regularly decreasing water allocations to vineyards. Droughts are getting worse and are lasting longer, and demands for the protection of rivers and aquifers are increasing. Yet plantings intended for high-yielding vineyards continue to be made on water-demanding, highly drought-vulnerable, rootstocks. No ‘5C’ mass-selection will protect against this. Nor, depite its being as ‘powerful’ as it is, will true SO4. It is not drought resistant and its large root systems are no defence against the effects of sustained sub-soil drying as irrigation water volumes are mandatorily decreased or even cut off altogether. As for those continuing to plant on C3309, Schwarzmann, 101-14, Riparia Gloire, etc.: your time is close to finished and the sustainability of your vineyards is under very real threat as a result. All of these mere ‘easy times’ stocks are fast becoming a path to serious vineyard collapse as volumes of irrigation water and rainfall continue to decline in Marlborough, Nelson, North Canterbury, and Hawkes Bay. And both ongoing climatic trends and ever tighter water use restrictions place their utilisation and their future in increasingly grave doubt.

 

Ripening period

Given its genetics, ripening should be advanced or about the same for scions on the GRAD® DRC5 Super rootstock.

 

Availability

This unique new stock is available exclusively from Stanmore Farm. Material for grafting is available for order now.

Vines grafted with GRAD® DRC5 Super rootstock are available through Stanmore Farm nursery under exclusive license from GRAD® 

E-mail for orders or inquires: orders@stanmorefarm.co.nz
Phone: 0800 Stanmore (0800 782 666)  or Contact Harry on 022 132 4503

Please note that a strict and comprehensive non-propagation contract must be signed off as part of your purchase order.

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 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

Author: Dr. Gerald Atkinson

Company director, viticulturist, grapevine researcher and historian, and sometime wine-writer.