Mixtures are described comprising two or more compounds selected from at least two of the following groups: i) salicylic acid and/or its functional analogous products (ESA), ii) promoting compounds (PRO) and iii) modulating compounds (MOD), and their use for stimulating the natural defence systems of plants and for inducing resistance in plants. The use is also described, of two or more compounds selected from at least two of the following groups: one or more compounds belonging to the ESA group and/or one or more compounds belonging to the PRO group and/or one or more compounds belonging to the MOD group, individually adopted by means of application programs which envisage alternating application, to stimulate the natural defence systems of plants and inducing resistance in plants.