The invention discloses application of
guaiacol to preventing and treating tobacco diseases and a method for applying the
guaiacol. The application and the method have the advantages that the
guaiacol can be applied to the field of
agriculture, the tobacco diseases can be prevented and treated by the aid of the guaiacol, and accordingly novel application of the guaiacol is developed; the guaiacol,
chitosan and other auxiliaries can be sprayed in a matched manner when the guaiacol is applied, and accordingly the tobacco diseases can be effectively prevented and treated; the guaiacol is low in production cost as compared with existing other
disease-preventive and
disease-resistant pesticides, and accordingly the application and the method are worthy of being popularized.