MAGNESIUM TO IMPROVE BERRY QUALITY
Magnesium contributes to the formation and storage of sugars. Applying magnesium to your vines through the leaves will help ensure optimal physiological functioning of the crop. At the heart of chlorophyll, magnesium is the essential link for photosynthesis and therefore for plant growth.
When applied late, Magnesium contributes to the growth of the bunch. By increasing the Magnesium content, this helps to limit the drying out of the stems which results in a halt in the ripening of the grapes (acidic berries, lower alcohol content).
THE APPLICATION OF MAGNESIUM IS RECOMMENDED UNDER THE FOLLOWING CONDITIONS:
Magnesium deficiency is found in sandy soils and calcareous soils.
Soils with acidic pH (less than 6) which have lost most of their cations (desaturated soils) despite a sufficient exchangeable Mg content.
A K/Mg ratio > 8 in petioles at the veraison stage is a good indicator of the risk of Mg deficiency.
For rosé wines
Like white wines, rosés can benefit from nitrogen and sulfur additions during maturation (post-veraison). This helps prevent stuck fermentation during vinification and accentuates floral notes. This strategy is well-suited to grape varieties such as Cinsault, Grolleau, and Grenache Gris.
Magnesium improves resistance to oxidation, especially in Syrah, Cabernet Sauvignon, and Grenache. When supplemented with phosphorus, rosé wines gain brightness and color, imparting a certain liveliness that is highly appreciated by consumers.
For white wines
Foliar nitrogen and sulfur additions, in sulfate form, help improve the thiol potential of white wines. These elements are essential for the synthesis of sulfur amino acids (SAAs) that form glutathione. This is then consumed by yeasts and reappears following alcoholic fermentation. This strategy can be applied to fruity white wines (typically a Colombard) to obtain certain notes of citrus, grapefruit, or even boxwood, accentuated by the presence of glutathione.
On grape varieties with terpenic aromas, fine and discreet (Gewurztraminer, Macabeu, Grenache, Roussanne, etc.), the combination of sulfur and phosphorus is more effective. Indeed, phosphorus is involved in the energy metabolism of cells, which reinforces these terpenic aromas and provides an interesting and complex complement.
For red wines
Magnesium deficiencies are very often observed during ripening in grape varieties such as Cabernet Sauvignon, Cabernet Franc, or Pinot Noir.
This deficiency is regularly observed following heavy rains before the harvest.
These rains are followed by an absorption of potassium and nitrogen from the soil into the woods. This phenomenon disrupts the ripening of the berries and induces a greater risk of end-of-cycle diseases. Phosphorus helps strengthen the vine's natural defenses while magnesium will accentuate the color and the fat character, which is accompanied by a fairly clear enrichment in polyphenols.
Winemaking can be impacted by the fertilization program and strategy in the vineyard. Numerous studies demonstrate the effects of foliar application at veraison, as well as optimal nutrition during fruit development.
Fertilization is too rarely considered as a pillar and ally in vineyard nutrition strategies. And yet, nutrients, provided in the right dose, at the right time and in the right form, greatly contribute to producing quality wines, revealing their typical characteristics and authenticity.