The invention concerns a method for prophylaxis of infections by fungi, particularly by oomycetes, and of bacterial infections in crop and ornamental plants. Areas of application are vine, fruit, vegetable and ornamental plant growing. The problem underlying the invention is that of developing a method for prophylaxis of infections by fungi, particularly by oomycetes, and of bacterial infections, particularly by downy mildew (Peronosporales) and Pseudomonas syringae, in vine and vegetable cultivation. Surprisingly it has been found that selected proteases, alone and in combination with complementary enzymes, effectively prevent the infection of plants by certain phytopathogenic organisms. The protected plant is not infected. Hence propagation of the pathogen within the plant stock is prevented. The method of the invention is characterized in that an aqueous solution of a protease, alone or in combination with β-glucanases and/or chitinases, is prepared, stabilizers, stickers and wetters are added, and the additized solution is applied by conventional techniques to the plants a number of times within the vegetation period, preferably ahead of weather-related phases of high infection threat.
