Nutrients Sulfur: Generalities
Sulfur has two important functions on the plants: nourishment and care from fungal diseases.
Regarding nutrition, sulfur is considered a secondary element (mesoelement) that is important for the life of all plants and for the quality of production, sulfur needs are lower than macroelements (nitrogen, phosphorus, potassium) but higher than trace elements. It is contained in plants in average percentages of 0.15-0.20%. Most of this element is found in the form of mineral deposits consisting of elemental sulfur, pyrite fossils and volcanic deposits. In soils, most of Sulfur is linked to the organic substance, but the most active is the mineral fraction that is absorbed by the plants. This element demonstrates its importance for plants in the formation of many compounds: it enters the composition of enzymes, vitamins, stimulates the absorption of nitrogen and phosphorus and is also indispensable for the activity of some soil bacteria, the sulfobacteria which oxidize sulfur in sulphate, making it available to crops. It is then necessary for the formation of proteins, being the basic constituent of two amino acids: cystine and methionine. It improves the chemical-physical characteristics of the soil, reduces the pH and favors the absorption of meso and microelements, thus reducing any deficiencies. The beneficial effects of sulfur on plants, must not only be attributed to its direct contribution, but also to the indirect actions it has against the soil, improving its chemical and physical characteristics and increasing its fertility.
The symptoms of a solfocarenza of the plants, above all if not marked, are difficult to ascertain, but generally the most obvious and recurrent are:
· Small plants
· Delay in maturation
· Young pale green leaves (also the ribs)
· Yellowing of the leaves starting with the oldest ones
· Shortening of internodes
· White and intensely branched roots.
In addition to the properties just described of sulfur at this point it is also important to remember its anticryptogamic effect. Sulfur is undoubtedly the "prince" product in the antioidic defense. Its action differs from common "systemic" fungicides because it does not penetrate into the tissue and plant sap and therefore does not cause toxicity and resistance.
Powdery mildew is a fungal disease that occurs on the leaves of affected plants with a whitish efflorescence, of a powdery appearance. Subsequently the whitish spots necrotize starting from the central part with curling of the main vein and death of extensive leaf portions, with consequent general deterioration of the plants. Treatments made in a preventive or curative manner with sulfur-based products avoid the onset of this serious disease while preserving the growth and flowering of our plants.