QUITTFOSS P, is a product that basically combines two active ingredients: the polymer of Chitosan (poly-D-glucosamine) and the phosphorous acid. The two active ingredients are elicitors of the secondary metabolism, through the modulation of PAL (Phenylalanine Ammonium Liasa) and, therefore, Activators of the Immune System of plants through the SAR mechanism. The idea of combining pure phosphorous acid with this polymer is to stabilize it with the latter avoiding the use of a salt. The purpose is to have a product that only combines chitosan with phosphite ion in high quantities, in order to have a very good eliciting signal of the SAR mechanism, which among other things allows to produce high levels of phytoalexins. Excellent source of phosphorus and very good complement for the prevention of fungal attacks to the root system.