The invention provides a method for inducing the
immune system of plants by utilizing 4-methyl-1,23-thiadiazole-5-
formic acid (NK-F001), 4-methyl-1,23-thiadiazole-5-
formic acid (NK-F002), 4-methyl-1,23-thiadiazole-5-
formic acid (NK-F003) and methyl thiadiazole
formamide (SZG-7) to enable the plants to generate
plant virus resistance to protect the plants. The invention also provides the application of the
combined use of any two or three of 4-methyl-1,23-thiadiazole-5-formic acid (NK-F001), 4-methyl-1,23-thiadiazole-5-formic acid (NK-F002) and 4-methyl-1,23-thiadiazole-5-formic acid (NK-F003), methyl thiadiazole
formamide (SZG-7) and diazosulfide (active ester, BTH), Tiadinil (TDL) and DL-beta-propalanine, virazole, ningnanmycin, antofine,
virus satellite No.1 and
virus satellite No.2 and XY-13 and XY-30 to improve the
plant immunity to induce the plants to generate antiviral activity and processed dosage forms of the single preparations and the mixtures and the composition and the content of effective components in the dosage forms. The invention discloses the range of the plants which can be induced by the compounds and composites thereof, the antivirus range of the induced plants, and the application of the compounds and composites thereof in protecting the plants in the field of agricultural field and horticultural filed.