The lively dispute between the two most used farming systems
In many Italian wine-growing areas, a rather lively dispute has arisen for some years between two of the most used training systems, namely the spurred cordon and the Guyot. The latter, which in its structural aspects is similar to the spurred cordon, from which it differs exclusively for the long rather than short pruning, is spreading in different hilly areas of Italy, not particularly fertile, since it allows to obtain an optimal foliar density and a balanced and healthy production, without requiring costly sprouting interventions, defoliation and thinning of the bunches.
The favoritism of legislative regulations
In recent decades, the spurred cordon has had a significant expansion, above all because it allows to mechanize all cultivation operations. In various Italian areas, also following the implementation of European Union regulations concerning economic aid for the restructuring of vineyards, the spurred cordon system was favored, which involved over 90% of the newly planted vineyards. Having given this system a higher score than the others, by virtue of the integral mechanization and the containment of production costs that it boasts, has contributed to its spread, regardless of the vigor of the cultivation site and the vine / rootstock combination. The experience in the vineyard of the last few decades affirms that the spurred cordon is decidedly reliable and capable of ensuring a balanced and high quality production, especially in hilly areas characterized by low vigor and / or with the use of not vigorous rootstocks ( e.g. 420A, 3309 C, 157-11 C).
Contain yields: too often this is the problem
In the case of vines with high bud fertility (greater than 1.5-2) and high cluster weight (greater than 250-300 g), the problem of limiting production within the limits imposed by numerous DOC and DOCG production regulations , or 9-10 tons / hectare, is difficult and economically onerous, especially if grown on fertile soils and / or with vigorous rootstocks (eg 140 Ruggeri, 779 and 1103 Paulsen). Among these vines are, for example, Sangiovese, Montepulciano, Ciliegiolo, Tocai rosso, Canaiolo nero, Nero d’Avola, Carignano, Sagrantino, Refosco, Trebbiani, Malvasie, etc. Furthermore, in such conditions the spurred cordon manifests two problems: 1) permanent cords age prematurely, as the desired annual cuts, to be carried out rigorously on one-year-old wood, cannot always be ensured; therefore it is necessary to resort to cuts on the branches of 2 or more years, which is followed by a greater susceptibility to fungal wood diseases; 2) presence of foliar thickening in the productive belt due to a high emission of buds from the crown buds and from the sub-buds, making intense scacchiation and / or defoliation necessary.
Management of the spurred cordon
In the presence of productive vines, due to high bud fertility and weight of the bunch, especially if grown in fertile areas, spurred cordon training often requires the containment of the hectare production, in order to avoid exceeding the limit imposed by the disciplinary, which can be obtained in winter pruning in two ways:
- Low number of buds + intense sprouting of shoots
- Right amount of buds + thinning of the bunches
Condition 1) is achieved by leaving short spurs strictly pruned to only 1 knot, while condition 2) is achieved with spurs of 2 knots each.
Condition 1: in the case of short pruning of the spurs with a single node, there will be the development of numerous shoots from the crowns and sub-buds, as well as from the latent buds along the permanent cord (Fig. 1). Consequently, a systematic and careful operation of removing the excess shoots is necessary, to be carried out within the month of May, with a request for manual work that can even exceed 50-60 hours per hectare.
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Condition 2: if you rely on more buds than the ideal one, achievable by setting spurs of 2 knots each, you will necessarily exceed the maximum production limit allowed by the specification (Fig. 2), and then it will be necessary to intervene with a thinning of the clusters (which obviously it loses the character of corrective action one-off and instead acquires the role of an inevitable and therefore systematic cultivation operation). This entails an increase in costs, as this strictly manual operation can take up to 40 hours / ha.
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Guyot versus spurred cordon
With the same pedo-climatic and management conditions, compared to the spurred cordon, the Guyot generally shows a reduction in the vigor and leafiness of the wall followed by less interception of light during the day (Fig. 3) and photosynthetic capacity of the foliage. Direct experiments carried out in central Italy on the Grechetto vine, as well as on Sagrantino and Sangiovese, show that in the Guyot the lower density of vegetation can also be estimated visually, as well as the ability to intercept the light which, in pre-harvest between 10 and 11 in the morning, it was reduced on average by 20-25%, passing from 80-85% of the spurred cordon to 55-60% of the Guyot (Fig. 3).
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These data underline how the Guyot, under the same pedo-climatic and management conditions, ensures a reduction in leafiness and vigor compared to the spurred cordon. From a production point of view, the Guyot slightly reduces the weight of the grape and therefore the unit productivity which is followed by a decrease in the degree of compactness of the bunch with positive implications on tolerance to fungal diseases. On the other hand, in these circumstances, the spurred cordon ensures a higher sugar concentration in the grapes (on average + 0.8-1 ° Brix).
Changing habits while running
By virtue of the above, for some years now, numerous wineries have begun operations to reconvert the training system from spurred cordon to Guyot by cutting the trunk and raising fruit-bearing heads.
Application considerations
It should be emphasized that no farming system is without problems and can therefore represent a panacea, that is, it can be used anywhere and with all vine / rootstock combinations. The following tables show the strengths and weaknesses of the two training systems in question which provide useful information for the choice between spurred cordon and Guyot to be adopted in future systems or in anticipation of a possible conversion, if the results are -qualities of the existing vineyard are not satisfactory.
SPERONED CORD
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GUYOT
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