А mixture of amino acids and carbohydrates, used as supplementary food and for the attracting natural enemies in a plum orchard, is also a nutrient substrate for the fungus Clasterosporium carpophilum Aderh. Treatment of the trees with this mixture promotes the development of the disease and, to a lesser extent, its spread. The spring treatments are the most dangerous for the plant. Since July, the disease is suppressed due to high temperatures and low humidity. In a plum ecosystem, applying of this technique in the second half of the summer will be determined by temperature indices and by how effective it will be as an additional food for the natural enemies.