The invention relates to a method for applying a natural extract from the vine with the aim of enhancing resistance of grapes to fungal infection and maturation, including the spraying of and irrigation with said extract on the vine and stalks in grape crops or directly on the harvested grapes with the purpose of preserving the grapes during storage. The invention also relates to the above-mentioned treatments using any natural or manufactured extract from the vine obtained by extraction with ethanol or another appropriate solvent with the purpose of enhancing natural resistance of the grapes.