Grapevine & Wine 06/04/2009

The climate changes and the viticulture changes, too

The world is wondering about climatic changes. As for vine, the best results are granted by manual interventions

The viticulture all over the world is wondering about the adaptation to climatic changes. As Mario Fregoni, head of the Fruit and Viticulture Institute of the Catholic University of Piacenza, sais: “The rising of global temperature is unequivocal, and it produced in the last years a worrying water stress in vines, raising the synthesis of sugars, anthocyanins and tannins, with repercussions on the color and on the fragrance of wines. We have to rethink the way we care vines.
The adaptation of viticulture to climate changes leads to new conditions that should be taken into consideration before the re-plantation of a vine. E.g., the moving of vines in latitude and altitude, the replacement of some varieties (red instead of white and vice versa), long wintry pruning performed in two different times, over-foliage irrigation (Sprinkler irrigation) and anti-stress mineral treatment for leaves. As a matter of fact, we can not presume to face the stress with irrigation, since vine does not need many water because of, if too irrigated, it get accustomed to it, lowering the grape quality level”.

Jim Wolper, of the Department of Viticulture and Enology, University of California, Davis, reported the interesting methods applied in California to face the same problem. He reported the use in California of the “mechanic green pruning”. Danny Schuster (New Zeeland), wine producer and viticulture expert, and Andrea Poletti (Italy), agronomist and viticulture expert, reported their experience in “The manual intervention to the green vine foliage in New Zeeland and Italy: technique and practice”. In California, as Wolper explains, after some negative results with the massive foliage pruning, we modified the culture light and sun exposition, the grafting techniques, and, in particular, we optimized the management of foliage. Up to now, the best results were granted by manual operations (allowed by an abundant manpower), but the optimization of mechanical leave pruning could be the future challenge.

Also Danny Shuster highlighted the great changes take took place in the Californian and the New Zealander viticulture where, through the employment of mechanical procedures for the green management, it was possible to optimize the big changes occurred in viticulture in recent years. Less watering, switching between chemical fertilizers and natural manure and shorter vegetative cycles. To date, the best results with mechanization are achieved with small-foliage plants, characterized by open foliage and a more distributed irradiation.
Giancarlo Spezia, professor of Vine mechanization at the Fruit and Viticulture Institute of the Catholic University of Piacenza, gave a report about the “Mechanic green pruning in Italy” that essentially consists in loping and leave cutting. The latter, in particular, is a very recent insertion in Italy, and it should still be considered in an embryonic stage.

According to Spezia: “in Italy, the mechanical loping boomed in ‘80s. There are no official numbers about the number of loping machines in Italy at the moment, but they are supposed to be between 5,000 and 7,000. This is not a high value if related to the total vine surface, but it can be ascribed to the strong division of agricultural surface in Italy, that results in an average farm surface of 1 hectare. As a matter of fact, for the simpler loping machines, the breakeven cost-benefic is approximately 4 hectares.

A look at the future: on one hand, it would be desirable the diffusion at lower costs of technologies in order to improve the automatic control of the machine position in respect to vegetation, optimizing, in this way, the dimensioning of foliage. Another important question is the diffusion of variable instalment technologies for the precision viticulture. In the next years it will be possible to access territorial maps of the vegetation vigor inside the same vine.

Finally, Fernando Martinez De Toda Fernàndez, Departemento Agricultura y Alimentaciòn, Logroño La Rioja (Spain), presented an interesting experience, the first in Spain and perhaps in Europe, of “the mechanical thinning of vine grapes”. It is an example of innovative technologies for the substitution of manual vine grape thinning. While to manual thinning has a high cost in terms of working hours, 500 euro/h circa, the mechanical thinning, through a vine trunk shaking, reduces the plan vigor, lowering costs to 120 euro/h circa. The same result is got through a premature leave pruning: this operation reduces the number of flowers and, consequently, the number of grapes.

di Lorenzo Brugali