Agricultural disease treatment agent comprises pure silicic acid 5-1500, disease and plant ash 3-300 mg, insecticide or fungicide (3-9 K minimum dynamo-dilution), and anionic surfactant of 100-800 cm3 minimum dynamo-dilution. Anionic surfactant without 0-500 cm3 dynamo-dilution is also applied. The mixture is made upto 1 litre with water.