Chitosan is characterized by protecting crops from pathogen and pest attacks, directly or indirectly, such as improving crop quality, or maintaining production stability during storage after harvesting. Chitosan is an elicitor that activates the self-defense capacity of the plant. Pathogens penetrate plants through three mechanisms: By their own means, by wounds and by natural openings (including stomata). Stomatal openings in plants provide a gateway for many pathogens, reducing these openings can provide an effective method to prevent the attack of pathogens that have chitin as a component of their cell wall. The products of the QUITOSANO line of ORANGESAFT activate mechanisms in the plant that order the closure of stomata.