The most common symptoms of nitrogen deficiency in nitrogen vines include shrinkage of the lower leaves, along with slow growth and relatively small grapes. Conversely, excessive nitrogen fertilisation can lead to excessive growth rates and shoot production, thus allowing fierce competition for these shoots and inhibiting fruit growth. As a result, the fruit produced will be of low quality and insufficient sugar content, while the acid content may increase. In addition, overgrowth of the vine has another negative consequence. Because too much foliage grows, it causes shade and insufficient air circulation. These conditions, in turn, increase the risk of disease outbreaks.
Potassium:Potassium deficiency manifests itself in the form of shrinkage around and between the leaves. At the same time, potassium deficiency can cause major problems for output. Symptoms include reduced yields, delayed ripening and smaller grapes. It may also affect the sugar content of the fruit and reduce its commercial value. On the other hand, excess potassium may lead to deficiencies in other nutrients such as magnesium or zinc, as they are competing elements.
Boron: deficiencies in boron can cause problems in grapes such as shrinkage of young leaves, uneven growth of leaves and berries, reduced fruit yield and absence of seeds in the fruit.
Magnesium: Magnesium is essential for the synthesis of sugars, which play the most important role in defining the distinctive organoleptic characteristics of each grape. Magnesium deficiency often occurs due to the high intake of potassium. It is also common in sandy, acidic soils. Symptoms include shrivelling and leaf margin necrosis.
Phosphorus: Phosphorus deficiency is not as common as nitrogen deficiency. However, it is often found in cold periods, in acidic or alkaline soils, in soils with a low organic matter content or in soils rich in iron. Symptoms of phosphorus deficiency first appear as small red spots on the leaves. This includes a reduction in photosynthetic capacity, fertility and fruit set. As a result, the yield of the vine is reduced.
Calcium: In sandy soils with a pH below 5.5, combined with a high degree of drought or an increase in sodium, calcium deficiency can occur. Contrary to other deficiencies, calcium deficiency does not manifest itself in the leaves but in the fruit.
Iron: we may observe iron deficiency in alkaline water-logged soils with increased levels of copper or manganese. Symptoms appear mainly on the youngest leaves, causing shrivelling between the veins of the leaves.
Zinc: Zinc deficiency manifests itself mainly in the young leaves. The young leaves become pale and at the same time we can observe asymmetry (one half of the leaf is much smaller and distorted than the other).