Keynote paper Canopy management: identifying the problems and practical solutions Richard E. Smart and Steve M. Smith Scientist, Viticulture and Technician, Viticulture MAFTech Ruakura Agriculture Centre Private Bag, Hamilton, New Zealand Abstract This paper discusses the implications for yield and qual- The effects of improper canopy management ity of excessively dense canopies. Simple techniques are Shade depresses fruit bud initiation as is shown by recent presented to identify problem canopies including measure- reviews (Kliewer 1982; Shaulis 1982) so that training sys- ments of canopy surface area, visual assessment of cano- tems which reduce within-canopy shade lead to increased pies, point quadrat measurements, leaf area measurement yield. Bunch rot incidence is also increased by dense cano- and measurements at winter pruning. Results are presented pies (Rotem and Palti 1969) and perhaps many of the to show how problem canopies can be overcome, with effects noted of pruning level, rootstock and fertilisation emphasis on shoot devigouration by pruning level and may be indirect effects through canopy microclimate. Shade training system. The economic advantages of some new effects on fruit composition are increasingly being training systems are presented. acknowledged, and a recent review (Smart 1985a) indicates that shade causes inferior fruit composition. For example, Introduction shade causes increased pH and K and malic acid concen- Canopy management consists of deliberate decisions by tration, and reduced sugar, anthocyanin, phenol and fruit the viticulturist to achieve some desirable canopy configu- flavour concentrations. Light quality as well as light quan- ration, be it in terms of surface area, volume, leaf area per tity effects have recently been implicated as affecting grape- shoot, fruit exposure, shoot orientation or even vine phys- vine physiology, especially fruit ripening (Smart 1987b; iological status. Important to consider are the economic Smart 1987c). costs and benefits of "canopy management". Management Improper canopy management can cause increased includes concepts of problem identification and then their production costs also. For example, vines with long, heavy solution. I have observed (Smart 1987a) that many canopy canes can be more expensive to hand prune, and dense components are "under-managed"— for example shoot canopies can cause inefficiencies of spray application. Fur- orientation in Australian and Californian vineyards, where ther, modern canopy design aims to enhance mechanisa- shoot position is determined by the natural forces of gravity tion, especially for summer trimming and winter pruning and wind rather than the viticulturists intervention. along with fruit harvesting. Operations such as leaf pluck- Canopy management is being increasingly recognised as ing in the fruit zone are facilitated by orderly arrangement an important tool for manipulating wine grape yield and of shoots in the canopy. quality (Smart 1985a). This is not to suggest that canopy The appropriate management of dense shaded canopies management is the only factor to be considered in improv- is a major problem facing modern viticulture. In fact the ing wine quality. Planting with a high-health, genetically problem now is of higher incidence than ever before, due superior clone of the appropriate cultivar grafted to an to advances in virus elimination, fertilisation, irrigation, appropriate rootstock and matched to a suitable climate plant protection and weed control. In the past, inadequate is of paramount importance. Soil conditions are cultural methods caused devigouration and canopies were acknowledged also of being of considerable significance, often less dense. These problems are exacerbated in many particularly in interaction with the climate and manage- New World viticultural regions due to choice of excessively ment systems in regulation of water and mineral status. deep or fertile soils for vineyards. Such is commonly the Also important are timeliness of harvest, fruit protection case in New Zealand. and of course appropriate vinification and conservation. This paper will indicate the viticultural and oenological Identifying problem canopies implications of improper canopy management, how Canopy surface area determination problem canopies can be identified, and some practical and Canopy surface area can be determined by sketching the economic techniques of canopy management. The concept canopy end-section to scale and calculating the exposed of vineyard quality assurance will be introduced whereby surface area. Surfaces facing downwards are not included, using simple assessments the viticulturist is able to moni- though this ruling is recognised as somewhat arbitrary tor progress in canopy management. (Smart 1985a). Similarly, there is a small effect of row orientation which is ignored. Fig. 1 lists five sample canopy Proceedings Second international Cool Climate Viticulture and Oenology Symposium, Auckland, New Zealand. January 1988. gib Canopy management identifying problems ono solutions cross-sections and canopy surface area calculations for row scorecard has been modified over several years, and the spacings 1-3.6 m, and for divided and undivided canopies. MKIV version has eight characters each worth 10 points Dimensions for the first four trellises are given by Smart to be assessed, just before harvest. These are: canopy gaps, (1985a). These are: Bordeaux traditional, row spacing 1 m; leaf size, leaf colour, canopy density, fruit exposure, shoot Intermediate row spacing 2 m; Traditional (New Zealand), length, lateral growth, and growing shoot tip presence. row spacing 3m; and "U" or "Lyre" trellis with row spacing Table 1 shows the MKIV scorecard, with each parameter 3 m. The fifth design is the Ruakura Twin Two Tier (RT2T), assessed out of 10 points, for a total of 80. High scoring 3.6 m row spacing. It is a horizontally and vertically canopies have adequate canopy gaps, slightly small leaves, divided trellis under evaluation at Rukuhia Horticultural dull but green healthy leaves, low leaf layer number, high Research Station, New Zealand (Smart 1987a). fruit exposure, intermediate shoot length, limited or zero lateral growth and no growing shoot tips. This scorecard is being used to evaluate experimental and commercial vine- yards, and is proving a useful tool to determine manage- ment strategies. Row spacing •1m Canopy SA•I9,000 m2/ha Point quadrat assessment x/h•088 This technique uses a long (ca. 1 m) thin (ca. 3 mm) straight, sharpened metal rod inserted through the canopy to record "contact" with canopy components (fruit and leaves— shoots can generally be ignored). For vertical cano- Row spacing • 2m pies, the rod is inserted horizontally in the fruit zone. For I Canopy SA •18,000 m2/ha x/h .1 00 non-vertical canopies, the rod is inserted at an angle (say 45-600) towards the fruit zone. By recording contacts as the rod progresses, and with a sample of say 100 insertions per canopy, the following can be readily calculated: Row spacing ■ 3m Canopy SA • I2,330 m 2/ha Percent gaps—number of insertions with no contact/100. x/hal.56 Leaf layer number (LLN)— total number of leaf con- tacts for all insertions/100. Row spacing • 3 m Percent interior fruit—number of contacts with fruit not Canopy SA 223,330 m 2/ha at the canopy exterior divided by total number of fruit x/h• 0.5 contacts. Percent interior leaves— number of contacts with leaves not at the canopy exterior divided by total number of I RT2T" leaf contacts. Row spacing • 3.6m Canopy SA • 21,110 m 2/ha These measurements and calculations can be readily x/h • 100 made, and provided sampling is adequate can accurately describe canopies. Fig. 2 shows the results of assessing five experimental Fig. 1. Vineyard cross sections drawn to scale, and calculated canopy sur- Cabernet Franc canopies at Rukuhia. The higher LLN of face area and ratio x/h (see text). standard vines was associated with lower canopy gaps, and The small canopy surface area of traditional, undivided higher proportions of interior leaves and clusters. The con- canopies is apparent, a primary cause of canopy shading. verse was true for RT2T vines with the low mean LLN of Sunlight interception will be proportional to this value. 0.73. Note that the proportion of interior fruit is about Canopy surface area is increased by decreasing row spac- twice that of interior leaves, due to the fact that leaves are ing, or by canopy division as for the "U" and "RT2T". The able to adjust their position to optimise illumination and ratio of distance between canopies (x) to their height (h) clusters cannot (Smart et al., 1982). is important. Smart (1985b) has suggested that when this Leaf area assessment value is less than 1.0 then shading at the base of canopy walls may be excessive. For this reason, the value of canopy Shoot leaf area can be readily calculated by comparing surface area for the RT2T (21, 110 m 2/ha) is at about the the fresh weight of a known number of discs of known maximum value possible. area (cut with a cork borer) to the fresh weight of leaves. Leaf area can also be measured with electronic meters and Visual assessment of canopies by correlations with length measurements. It is instructive Canopy gaps, canopy density and fruit exposure can be to separate main and lateral leaves, and also to record shoot readily visually estimated. This leads to the concept of a length. Sufficient shoots need be sampled to obtain a "vineyard scorecard" first developed in South Australia in meaningful average. Leaf area per. vine can be calculated 1981 (Smart et al., 1985). With sufficient instruction and by multiplying with the average shoot number per vine. experience, scorers can give similar answers. Estimates of The ratio of leaf area to canopy surface area (LA/SA) can canopy density can be incorporated with other visual esti- be then determined. Ideal values of this figure should be mates of physiological significance to make an assessment 1.2 or lower (Smart 1984); note that for tall thin canopies of the potential winegrape quality from the vineyard.