By: Dr. Richard E Smart and Amaya Atucha
We wrote this article to promote the use of the Scott Henry training system in vineyard regions of North America; for reasons which we do not completely understand the system has been overlooked, under-researched and also under-promoted. For those growers who use this system, mostly overseas, the benefits are substantial. They might be summarised as improved yield and fruit composition and reduced disease incidence. Wine quality is also improved. The system is not difficult to manage, contrary to some rumours in this regard. It is a matter of learning new tricks, mostly about timing, so not too difficult for commercial grape growers.
For those growers prepared to try new ideas, you will be rewarded, and the winemakers (and bank managers) will smile.
Why the Scott Henry?
Canopy Management 101
The basic aim of canopy management is to train grapevines in in such a way that yields are promoted, as is desirable fruit composition and disease avoidance. It follows a few basic principles, which follow:
- Maximise sunlight interception, remember it is Sunlight into Wine. Preferably use north-south rows, spaced about as far apart as they are tall. If you are in a hot, sunny region, you might avoid N-S rows and the heat caused by afternoon sun on west-facing canopies. Taller canopies are of course more efficient than shorter ones.
- Maintain a sufficiently wide spacing between shoots to avoid dense canopies, around 5 shoots per foot of canopy length, or 2.5, 2-bud spurs per foot of canopy. Most canopies are more crowded than this. Shading of bunches has serious effects on wine quality, and shading of the base of shoots reduces bud fruitfulness.
- Fruit exposure will generally be sufficient in such low density canopies as above; perhaps if very leafy there may be a need for some leaf or lateral removal.
- Vine balance is very important, and this is largely determined by winter pruning level; the bud count should be matched to the vineyard vigor. The best way to assess this is by weighing prunings on a few average vines. To obtain vines of moderate vigour, the rule of thumb is retain about 14 buds per pound pruning weight. This is often more buds than are normally left. Ideally the vines should be spaced 5-6 ft apart in the row.
These general rules apply to any vineyard trained to any system, not just the Scott Henry. The Scott Henry (SH) is like the Smart Dyson (SD) and Geneva Double Curtain (GDC) systems. All three have two feet of canopy per ft of row, in other words they are a “divided canopy” system. The Scott Henry and Smart Dyson are called vertically divided. One canopy grows upwards, one downwards from mid height (3 ½ ft) fruiting zones. The GDC on the other hand is horizontally divided, with two pendant curtains about 3 ft apart.
Managing the Scott Henry
The Scott Henry is a cane pruned system, using two or four canes. The Smart Dyson is spur pruned, with spurs pointing upwards and downwards from a mid-height cordon. We will discuss the management of the Scott Henry only here.
Normally, for vigorous vines we prune to four canes, two on a lower fruiting wire at around 40”, two on an upper fruiting wire at about 46”, on the opposite side of the post and on the upwind side. An extra wire is used for the SH, a moveable foliage wire to help downwards shoot positioning. At winter pruning, this rests about opposite the top fruiting wire, and at early flowering it is placed on top of the shoots from the bottom canes after they are separated from those growing upwards; subsequently, after fruit set it is moved downwards and attached, so positioning the shoots downwards. When pruning remember not to wrap the bottom canes too tightly, one or two wraps is best, and secure the ends of the canes.
At the beginning of flowering, and before the tendrils start to attach, slide your arm into the canopy to separate shoots from the top and bottom canes. Place the extra moveable foliage wire on top of the shoots from the bottom cane, and they will lean out into the row, assisted by any wind. Shoots from the top cane will form the top canopy, and they are trained vertically upwards between foliage wires, as is normal for VSP.
Then, at around early fruit set, move the bottom moveable foliage wire downwards and attach it to the post, say 2 ½ ft below the fruiting wire. This will form the second, downward pointing canopy. Remember that you will need to apply any herbicide before flowering.
Normally shoot positioning the Vertical Shoot Positioned canopy (VSP) takes 3-4 labor passes through the vineyard with well managed teams, and requires 12 to 16 hrs per acre. This figure might be increased by say 25% maximum when using Scott Henry.
Responses to Scott Henry
Training with Vinifera
The conversion cost is not high, to add only one wire per row to train shoots downwards, and a very modest increase in labor input, for shoot positioning. The benefits are however substantial, with yield increase to 30% or more, no change in other costs (apart from harvest), and typically less disease. It is well known that powdery mildew and Botrytis are higher in shaded canopies, and less for Scott Henry than VSP. Because of improved bunch exposure, there is better color, flavour and phenolics in vines trained to Scott Henry.
Most experience around the world is with vinifera grapes; in fact Oyster Bay wines of New Zealand has 5,240 acres of Scott Henry planted in both NZ and Australia, no doubt the largest in the world. Results from their vineyards reinforce the message above, and on a grand scale!
Responses to Scott Henry Training
With Hybrid Grapes in Wisconsin
Cold climate hybrid grapes cultivars have propelled the expansion of the grape and wine industries in the Northeast and upper Midwest of the United States, mostly due to their superior midwinter hardiness compared to vinifera and other hybrid cultivars. However, cold climate hybrids possess high vegetative vigor which can be intensified when vines are grown in very fertile soils, and summer rainfall such as in the Midwest. The high vegetative vigor of these hybrids can be challenging for growers to manage, and often results in dense canopies with shaded fruit that is high in acidity and has poor color development, as well as an overall delay in ripening. To control vigor, growers will usually hedge and skirt shoots multiple times during the season, and will implement shoot and leaf removal to increase light exposure of clusters, all of which requires labor and increases production costs. Particulary time consuming is the task of tucking shoots into the trellis wire in the VSP system, which can be a constant battle with cultivars that have a procumbent (droopy) growth habit such as ‘Brianna’ and ‘La Crescent’.
Alternatively, divided canopy training systems, such as Scott-Henry (SH), can be used to control vine vigor, as these systems increase the number of shoots and clusters per unit of row length, compared to those grown on single canopy systems like VSP or high wire. Studies across in the Midwest of the United State (Atucha and Wimmer, 2016; Cochran and Nonnecke, 2016) have shown that cold climate hybrids trained on divided canopy systems can achieve higher yields, reduce canopy shading, and improve fruit composition, compared to single canopy systems.
In a 5-year training system evaluation study in southern Wisconsin, yield of vines trained to the SH system produced more than double the yield than those trained to the vertical shoot positioning (VSP) system, and 25-35% more than vines trained to the high cordon (HC) system. For example, in ‘Frontenac’ the 5-year average yield on SH was 30 lb/vine ( 8.7 t/ac), compared to 16 lb/vine (4.7 t/ac) in VSP, while in ‘Marquette’, HS and VSP produced 17 and 10 lb/vine (5 and 2.9 t/ac), respectively. In addition to higher yields, vines trained in the SH system had more consistent yields year to year, compared to the high variability in yields observed in VSP.
The higher yields in SH resulted in a considerable reduction in vegetative vigor, which required no to minimal hedging to control shoot growth in vigorous cultivars such as ‘Marquette’ and ‘La Crescent’, and an overall more open canopy with a higher percentage of clusters exposed to sunlight (Wimmer et al., 2018) . There were no differences in sugar and acid composition at harvest between the higher yielding SH vines and those in VSP or HC, despite the significantly higher crop load of vines trained to SH. Separate studies in Wisconsin have shown that sunlight exposure improves berry colour and phenolics. A recent article in this magazine (Smart 2018) emphasised the need to do shoot positioning on the high wire trellis to avoid shading, which causes loss of yield and quality.
We think that Scott Henry and Smart Dyson might have application in the Midwest USA, as has been found elsewhere. Certainly the initial research results are encouraging. The SH training system is a great option to control vegetative vigor and increase yields in cold climate hybrid grape cultivars without reducing fruit ripeness, and quality for winemaking will likely be improved.
Atucha, A. and M. Wimmer. 2016. Brianna, Frontenac, La Crescent, and Marquette Training Trial. West Madison Agricultural Research Station (WMARS), Verona, WI. Northern Grapes Project publication. http://northerngrapesproject.org/wp-content/uploads/2016/02/WI-training-study-Year-4.pdf
Cochran, D.R. and G.R. Nonnecke. 2016. Iowa Training Systems Trial. Snus Hill Winery, Madrid, IA. Northern Grapes Project publication. http://northerngrapesproject.org/wp content/uploads/2016/02/IA-training-study-Year-4.pdf.
Smart, R. E. (2018) Managing high wire trellis for improved yield and quality. The Grapevine. Nov-Dec, pp 54-58.Wimmer, M., Workmaster, B. and Atucha, A. 2018. Training Systems for Cold Climate Interspecific Hybrid Grape Cultivars in Northern Climate Regions. HortTechnology 28(2): 202-211.
About The Authors
Dr. Richard Smart: is an Australian viticulturist and leading global consultant on viticulture methods and is often referred to as “the flying vine-doctor”. He is considered responsible for revolutionizing grape growing due to his work on canopy management techniques.
Dr. Smart is a graduate from Sydney University with Honors in Agricultural Science in 1966. Additionally he holds the degrees M.Sc (Hons) from Macquarie University following a study of sunlight use by vineyards, a Ph.D from Cornell University in New York State studying under the Professor Nelson Shaulis, and in 1995 awarded a D.Sc. in Agriculture by the Stellenbosch University, South Africa, in recognition of research into canopy management effects on vineyard yield and quality.
Dr. Smart is the author of the book Sunlight into Wine as well as a contributor to several trade publications, and the viticulture editor of The Oxford Companion to Wine. Consulting has been a full time occupation since 1991, and he has consulted to over 300 clients worldwide. While many clients want to use Richard’s expertise in canopy management to improve wine quality and vineyard yield, complete viticultural advice has been given on a range of issues like choice of site, variety, rootstock, irrigation and nutrition management. Dr.Richard E. Smart: International Viticultural Consultant, Smart Viticulture, Truro, UK, firstname.lastname@example.org
Amaya Atucha: is an assistant professor and Gottschalk Chair for cranberry research in the department of Horticulture at the University of Wisconsin-Madison and State Fruit Crop Specialist with UW Extension. She earned a B.S. in horticulture from the Pontificia Universidad Católica de Valparaíso (Chile) and a Ph.D. in horticulture from Cornell University. Her research program focuses on fruit crop physiology and production of deciduous fruit crops, predominantly cranberries and cold climate grapes, and her extension program delivers up to date, research-based information to fruit growers in Wisconsin. She edits the Wisconsin Fruit Newsletter, a biweekly newsletter distributed statewide in Wisconsin, and is a contributor to the Cranberry Crop Management Journal, a publication highlighting research and extension in cranberry production at UW-Madison.