Process for conferring a protection against a pathogen upon a plant by elicitation by an aqueous composition, the active agents of which are extracted from edible fungi (parasol mushroom, pleurotus, button mushroom). An alkaline extraction is carried out, then an enzymatic hydrolysis, to obtain a fraction less than 100 kDa. The process consists in spraying the aerial parts of the plant with the composition obtained in this way； this thereby acts to combat cryptogamic diseases of plants such as vines, fruit trees, vegetable crops and cereals.
