The invention provides a copper-based liquid formulation enhancing plant self-defence comprising between 10 and 15% of sodium lignosulphonate, between 15 and 25% of copper sulphate, between 0.20 and 0.40% of MSB and between 1.30 and 1.75% of free amino acids of plant origin, the rest being water, the percentages being expressed by weight with respect to 100% by weight of the final liquid formulation, as well as its application by fertigation, drip irrigation, by spraying, or by distributing it in areas close to the plant in surface irrigation.
