NOVELTY - Substituted benzoxa(thia)zole compounds (I) and their salts are new.    USE - (I) are useful to combat plant pathogenic fungus and treat transgenic plants (all claimed) e.g. wheat, barley, corn, cotton, soybeans and rice. (I) are useful to combat bacteria, insects, arachnids, helminths, nematodes and molluscs in agriculture, gardens, forest and hygienic sector. (I) are useful as herbicides, safeners, growth regulators, antimycotics, virucide, an agent to combat Mycoplasma like organism and Rickettsia like organism, insecticides and an intermediate product or precursor for the synthesis of further active agent. (I) are useful to protect technical materials such are adhesive, paper, cardboard, textile, leather, wood and plastic article against the attack of fungus. The ability of (I) to combat Spodoptera frugiperda was tested in Zea mays. The results showed that N-(4-(2,4-dichlorophenoxy)phenyl)-1,3-benzoxazol-7-carboxamide at a concentration of 500 g/hectare exhibited a fungicidal efficiency of greater than or equal to 80%.    ADVANTAGE - (I) exhibit good plant and environmental compatibility, and favorable warm blood toxicity. (I) provide plants with high yields, quality, increased tolerance against high or low temperatures, dryness or salinity, increased flowering rate, high nutritional value and/or good storage stability.    DETAILED DESCRIPTION - Substituted benzoxa(thia)zole compounds of formula (I) and their salts are new.    X1-X3 = O or S;    R1 = H, halo, 1-4C-alkyl, OH, SH, 1-8C-alkoxy, (1-8C-alkoxy)carbonyl, amino, 1-8C-alkylamino, di-(1-8C-alkyl)amino, 1-8C-alkylthio, 1-8C-alkylsulfinyl or 1-8C-alkylsulfonyl;    R2 = halo, OH, CN, nitro, 1-8C-alkyl, 1-8C-alkoxy, 1-8C-alkylthio, 1-8C-alkylsulfinyl, 1-8C-alkylsulfonyl, 1-4C-alkoxy-1-4C-alkyl, (1-4C-alkyl)thio(1-4C-alkyl), (1-4C-alkyl)sulfinyl(1-4C-alkyl), (1-4C-alkyl)sulfonyl(1-4C-alkyl), 1-8C-haloalkyl, 1-8C-haloalkoxy, 1-8C-haloalkylthio, 1-8C-haloalkylsulfinyl, 1-8C-haloalkylsulfonyl, halo-1-4C-alkoxy-1-4C-alkyl, halo-1-4C-alkylthio-1-4C-alkyl, halo-1-4C-alkylsulfinyl-1-4C-alkyl, or halo-1-4C-alkylsulfonyl-1-4C-alkyl;    m = 0-4, where R2 is same or different, when m is 2-4;    R3 = halo, OH, CN, nitro, 1-8C-alkyl, 1-8C-alkoxy, 1-8C-alkylthio, 1-8C-alkylsulfinyl, 1-8C-alkylsulfonyl, 1-4C-alkoxy-1-4C-alkyl, (1-4C-alkyl)thio(1-4C-alkyl), (1-4C-alkyl)sulfinyl(1-4C-alkyl), (1-4C-alkyl)sulfonyl(1-4C-alkyl), 1-8C-haloalkyl, 1-8C-haloalkoxy, 1-8C-haloalkylthio, 1-8C-haloalkylsulfinyl, 1-8C-haloalkylsulfonyl, halo-1-4C-alkoxy-1-4C-alkyl, halo-1-4C-alkylthio-1-4C-alkyl, halo-1-4C-alkylsulfinyl-1-4C-alkyl or halo-1-4C-alkylsulfonyl-1-4C-alkyl;    n = 0-5, where R3 is same or different, when n is 2-5;    R4 = halo, OH, CN, nitro, 1-8C-alkyl, 1-8C-alkoxy, 1-8C-alkylthio, 1-8C-alkylsulfinyl, 1-8C-alkylsulfonyl, 1-4C-alkoxy-1-4C-alkyl, (1-4C-alkyl)thio(1-4C-alkyl), (1-4C-alkyl)sulfinyl(1-4C-alkyl), (1-4C-alkyl)sulfonyl(1-4C-alkyl), formyl, 1-8C-alkylcarbonyl, 1-8C-alkylamino, di-(1-8C-alkyl)amino, 1-8C-haloalkyl, 1-8C-haloalkoxy, 1-8C-haloalkylthio, 1-8C-haloalkylsulfinyl, 1-8C-haloalkylsulfonyl, halo-1-4C-alkoxy-1-4C-alkyl, halo-1-4C-alkylthio-1-4C-alkyl, halo-1-4C-alkylsulfinyl-1-4C-alkyl, halo-1-4C-alkylsulfonyl-1-4C-alkyl, phenyl (optionally substituted by halo, CN, nitro, 1-6C-alkyl, 1-6C-alkoxy, 1-6C-alkylthio, 1-6C-haloalkyl or 1-6C-haloalkylthio), heteroaryl or heterocyclyl; and    s = 1 or 2, where two adjacent residue R2 is 4C-alkenylene, when s is 2.    INDEPENDENT CLAIMS are included for:    (1) an agent comprising (I), diluent and/or surface active agents;    (2) the preparation of (I);    (3) a nitrobenzoic acid derivative of formula (VIIIa) or its salt;    (4) an aminobenzoic acid derivative of formula (VIIa) or its salt;    (5) a 3-amino-benzoic acid methyl ester compound of formula (VIa) or its salt;    (6) a benzoxa(thia)zole carboxylic acid ester compound of formula (Va) or its salt;    (7) a benzoic acid compound of formula (IVa) or its salt;    (8) a nitro-benzene compound of formula (Xa); and    (9) a 3-nitro-benzoyl chloride compound of formula (XIa).    R4a-R4e, R4g = 1-8C-alkylsulfinyl, 1-4C-alkoxy-1-4C-alkyl, (1-4C-alkyl)thio(1-4C-alkyl), (1-4C-alkyl)sulfinyl(1-4C-alkyl), (1-4C-alkyl)sulfonyl(1-4C-alkyl), formyl, 1-8C-alkylcarbonyl, 1-8C-alkylamino, di-(1-8C-alkyl)amino, 1-8C-haloalkyl, 1-8C-haloalkylthio, 1-8C-haloalkylsulfinyl, 1-8C-haloalkylsulfonyl, halo-1-4C-alkoxy-1-4C-alkyl, halo-1-4C-alkylthio-1-4C-alkyl, halo-1-4C-alkylsulfinyl-1-4C-alkyl, halo-1-4C-alkylsulfonyl-1-4C-alkyl, aryl, hetaryl or heterocyclyl; and    R4f = halo, OH, CN, nitro, 1-8C-alkyl, 1-8C-alkoxy, 1-8C-alkylthio, 1-8C-alkylsulfinyl, 1-8C-alkylsulfonyl, 1-4C-alkoxy-1-4C-alkyl, (1-4C-alkyl)thio(1-4C-alkyl), (1-4C-alkyl)sulfinyl(1-4C-alkyl), (1-4C-alkyl)sulfonyl(1-4C-alkyl), formyl, 1-8C-alkylcarbonyl, 1-8C-alkylamino, di-(1-8C-alkyl)amino, 1-8C-haloalkyl, 1-8C-haloalkoxy, 1-8C-haloalkylthio, 1-8C-haloalkylsulfinyl, 1-8C-haloalkylsulfonyl, halo-1-4C-alkoxy-1-4C-alkyl, halo-1-4C-alkylthio-1-4C-alkyl, halo-1-4C-alkylsulfinyl-1-4C-alkyl, halo-1-4C-alkylsulfonyl-1-4C-alkyl, phenyl (optionally substituted by halo, CN, nitro, 1-6C-alkyl, 1-6C-alkoxy, 1-6C-alkylthio, 1-6C-haloalkyl or 1-6C-haloalkylthio), heteroaryl or heterocyclyl.