Precision Viticulture encompasses the philosophy of vineyard management in which each vineyard lot, and even each vine, is treated individually by hand and through the use of the latest technology in order to maximize quality.

Pruning

Often overlooked, pruning is one of the most important activities in vineyard management. This activity sets the stage for the vigor, yield and fruit distribution of each vine for the upcoming growing season. The vineyard manager must first establish the number of buds to be left, a decision which is dependant on the previous year’s vigor. This vigor level is established by weighing the pruned material of a sample plant in each vineyard lot. In general when pruned material exceeds 1 kilogram, the pruning leaves 16 buds, 8 on each cane in the double Guyot system. If less buds are left the vine will have excessive vigor in the next growing season. If the pruned material is less than 1 kilogram, only 14 buds are left, 7 per cane.

Another very important decision in pruning is the cane selection. The selected cane, which will act as the loader for the next year, must first have the proper vigor. It’s diameter should not exceed that of a pencil. It must also have a good spacing between buds in order to avoid congestion in the shoots and clusters. The cane should also be as close as possible to the trunk to ensure that the canes of neighboring plants do not superimpose on each other. After cane selection and pruning of the unwanted canes, the selected cane is lain flat against the first wire and tied. The cane must be as horizontal as possible in order to ensure an even bud break. If any of the buds are higher than the others, the highest bud will break and the others will not, resulting in a highly unbalanced plant.

Winter & Spring Irrigation

The desert climate of Mendoza makes irrigation not only a necessity, but also an important tool for maximizing quality. The season’s irrigation regime begins in August when ample irrigation is applied in order to replenish the soils water level to ensure a good start to the vegetative cycle. The regime is intended to achieve a water level of 2000 m3 per hectare, which is the equivalent of the soil having just received around 200 ml of precipitation. Small observational wells are dug in strategic parts of the vineyard in order to measure the soils water content. Throughout the spring season, irrigation is applied in order to maintain this water content level.

Suckering

After the danger of late frosts has passed, which for Mendoza is around November 4th, the process of suckering begins. Vinegrowers work the vineyard plant by plant removing all unwanted shoots from the trunk and any excess shoots that have emerged from the buds. The goal is to leave only one shoot per bud. This manual process ensures that the vines energy is properly channeled to the growth of the desired shoots, establishing the proper canopy size, ensuring proper, balanced fruit distribution and creating the desired congestion free microclimate in the canopy. This process is repeated throughout the year about once a month to ensure proper canopy balance.

Summer Irrigation

Throughout the summer months the irrigation regime is implemented based on various aspects of precision viticulture. Perhaps the most important technique is that of visual observation of the plants by the vineyard manager as he continuously walks the vineyard. The goal of the vineyard manager is to maintain leaf color in the canopy; a deep dark green indicating the photosynthetic activity is maximized. Another leaf character which can be visually observed is the angle between the stem and the leaf. If this angle is very small, and the leaf is sagging, the vineyard manager will apply irrigation. Leaf to tip positioning is also important. If the first leaf is above the shoot tip, then the plant is not working properly and so must receive irrigation.

In addition to these visual observations, precision viticulture also implements the latest water content measurement technology to make irrigation decisions. A Scholander pump, which measures leave water content through the application of pressure in a hermetically sealed box, is used to determine the water content of each plant. Currently the pump readings are being correlated with infrared readings of leaf temperature in order to further establish irrigation regimes which can be based entirely on leaf temperature readings. A certain leaf temperature will eventually lead to decisions on customized irrigation regimes to be implemented at various points throughout the growing season.

Leaf Thinning

This process is designed to solve any potential problems in aeration that might have developed throughout the year. The goal is to create a tunnel within the canopy and around the clusters to ensure an ample movement of air. Internal leaves are removed from inside the canopy to achieve this without overexposing the clusters to the sun, which in Mendoza can result in burnt fruit. In exceptional cases where increased aeration is necessary, perhaps to unusual precipitation, some exterior leaves might be removed to increase aeration even more. In such cases, only leaves on the eastern side of each row are removed so the clusters are not exposed to the more intense afternoon sunlight.

Vine Vigor Measurement

Precision viticulture utilizes the latest technology in infrared satellite photography in order to measure vine vigor. The goal of this process is to heighten homogeneity in the vineyard by identifying and marking plants which are outside of the desired parameters of vigor. Satellites bounce close frequency infrared waves off the vineyard. The vineyard in turn emits long frequency infrared waves back to the satellite. The intensity of the long frequency infrared waves is then used to create an NDVI map of the vineyard which shows the vigor of all of the lots. Armed with this data and a Global Positioning System (GPS) device, vineyard managers then walk the vineyard where the data shows heterogeneity in order to identify and mark those plants which are outside the norms. These plants are harvested separately, thereby increasing the homogeneity of the remaining plants in each lot. This increased homogeneity of ripeness level allows for the maximization of quality from each lot.

Green Harvesting

After veraison has occurred, the vineyard managers begin the process of green harvesting. Walking the vineyards and observing each cluster on each plant, vinegrowers remove those clusters which have not evenly changed their color. If there are any grapes on any given cluster that have not completely changed their color, those clusters are removed. This allows the vine to channel all of its energy in ripening those grapes which have successfully achieved veraison. This helps ensure that the proper relation between canopy size and yield is maintained, it increases homogeneity among the clusters and means that each of those clusters and grapes will be allowed to achieve a heightened level of maturity and concentration. This process is also designed to remove any weak shoots that will not be likely to ripen the clusters fully

Maturity Control

As harvest approaches, each vineyard lot undergoes regular and extensive chemical and tasting observation. Sample plants are chosen and undergo regular chemical analysis to establish sugar, acidity, anthocyanin and polyphenol levels. In addition to this chemical analysis, vineyard managers engage in extensive berry tasting in order to track ripeness levels. The berries and the skins are tasted in order to observe sugar levels and tannin ripeness. Also seed color is logged as an important indicator of grape maturity. The vineyard managers are looking for mature, sweet fruit flavors in the berries and ripe, sweet tannins in the skins. They are also looking for seeds with a dark brown color, indicators of an optimum ripeness level.

Hand Harvesting

In order to minimize any breakage or aggressive treatment of the grapes which could result in preliminary oxidation and loss of important components of color, aroma and flavor, all grapes are hand harvest. Harvesters use 20 kilogram baskets in order to minimize damage to the clusters. The clusters are then loaded into 250 kilogram plastic bins for their transport to the winery.

Conclusion

Precision viticulture is a very important philosophy for achieving heightened quality in the grapes and ensure a heightened quality in the resulting wine. Pain staking attention is paid to even the most minute of details throughout the vines growth cycle in order to maximize quality. Each vine is treated individually in order to realize its maximum potential.