Resistant Rootstocks for New York Vineyardspage 3Rootstocks for Vinifera Vineyards | |||
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There is some disagreement regarding the desirable vigor level for vinifera vines. Clearly vines which are growing actively late in the season are excessively vigorous because cold hardiness acquisition is delayed. However, vigor levels can certainly be too low, especially when small vine size is achieved by using practices which deprive the vine of factors needed for good function.
In the above figure, only one of the rootstocks, C. 3309, is a standard one for growing vinifera vines. Concord and Elvira have only partial phylloxera resistance and own rooted vinifera has none. The arrows indicate the average pruning weight, and the range of vine size is indicated by the length of the lines. Note that every stock produced a negative relationship between vine size and bud survival. Larger vines had more injury than smaller vines. However, when average vine size was reduced by phylloxera feeding or other maltreatment, the injury level at a given vine size increased. In other words, a large (3.5 lbs cane pruning/vine) vine grafted on C. 3309 had no more injury than a smaller vine grafted to Concord or Elvira.
| Vine growth, fruit yield, fruit soluble solids concentration and bud freezing temperature in January the following season for vinifera vines grafted to different rootstocks. | |||||
|---|---|---|---|---|---|
| Rootstock | Cane Prunings/Vine (lb) | Cane Prunings/foot of Row | Fruit Yield (tons/acre) | Fruit Brix | Midwinter Bud Freezing Temperature (°F) |
| C. 3309 | 3.2 | 0.4 | 5.0 | 19.4 | -12.1 |
| Own | 2.7 | 0.3 | 3.0 | 18.8 | -10.7 |
| Elvira | 1.8 | 0.2 | 3.6 | 18.2 | -11.5 |
| Concord | 1.8 | 0.2 | 3.7 | 19.4 | -11.5 |
Even though vine health is more important than vine size, most New York growers avoid the use of high vigor rootstocks such as 5C and 5BB for vinifera in New York. Most experience has been with C. 3309 which is very commonly used. The table above records 3 year means for the same vines. Note that the small vines not only are not as cold hardy as those grafted to C. 3309, but they also have inferior yield and fruit maturity.
The data above shows thae other side of the coin. Grafting to 5BB or 5C resulted in bigger vines, more bunch rot, less mature wood, more winter cold damage and lower average yield.
Although these data suggest that intermediate vine size is best, there are many reports in the literature that some low vigor rootstocks induce earlier wood maturity which not only aids cold hardiness, but prevents shoot growth from competing with fruit maturation in late summer. What has been missing is data. We have been investigating the realtionship between vine vigor, winter hardiness and yield for several years.
Beginning in 1992 we planted Chardonnay vines grafted to 23 different rootstocks. To date the results have been mixed. The data aabove is typical. Each point represents the mean for Chardonnay grafted to a different rootstock. Note that there are large differences in vine size, but January bud freezing temperature appears to have little relationship with vine size.
However, the effect of rootstock on early wood maturation may be more important. This data illustrates the mid-November, 1993, bud freezing tempearture for Chardonnay grafted to 14 rootstocks against the bud survival following January, 1994 temperatures of -16°F. Note that there are two types of response to rootstock. For most stocks there was an association with early wood maturation and increased winter survival. However, another group of rootstocks (the circled ones) had substantial injury in spite of obtaining early bud hardiness, and none of the late hardening stocks had less than 60% bud death.
This work will require time, not only to wait for further damaging winters, but to achieve true vine size response. The 1996 growing season was generally satisfactory, but it was the third year of above average crop size. Note there are substantial differences in Chardonnay vine size among these rootstocks, but also substantial differences in how the vine size is changing. C.1202 and own rooted vines suffered drastic loss in vine size in a year when most vines grew larger. This probably reflects the cummulative impact of phylloxera on these more suceptible varieties.
For the time being, our best advice is still to use the intermediate vigor stocks like C. 3309 or MGT 101-14, and for most situations, avoid the high vigor stocks like 5C, SO4 and 5BB. On the other hand these stocks may offer desirable stimulation to Native American and French-American hybrid varieties.
© Copyright 2000 Robert Pool
