Liquid fertilizer for the prevention and treatment of zinc, manganese or sulfur deficiencies. Its composition and the special form of sulfur (Liquid Bioassimilable Sulfur – LBS, product of nanotechnology) ensures good absorption and mobility in plants. Thus the product moves systematically whether it has been absorbed by the leaves or by the root. The content of the product in the trace elements zinc and manganese contributes to a more efficient photosynthesis and to the synthesis of auxins and helps both in the good vegetative growth and in the thickening of the fruits. Sulfur in turn is an important macronutrient for the production of nucleic acids, amino acids and many other substances including lignins. Its application to tomato plants in the face of stress achieves a significant increase in chlorophyll content in the leaves and better photosynthesis, high calcium deposition, increased concentration due to activation of the hormones salicylic acid and jasmonic acid2 and much reduced concentration of oxidin2).