1. Oxadiazoles, n-xides and / or their useful salts for agriculture, or methods for controlling phytotoxin fungi, or methods for controlling harmful phytotoxin fungi, including the treatment of fungi or materials, plants, soils or seeds to protect them from chemical attack, An effective amount containing at least one compound, nitrous oxide or an acceptable salt in agriculture； and an agrochemical composition containing at least one of the compounds and an agrochemical composition containing seeds. Claim 1: use of formula compounds (1),or the N-oxides, or salts thereof acceptable in agriculture, to combat harmful phytopathogenic fungi, characterized in that: A is phenyl or an aromatic heterocycle of 5 or 6 members, wherein the ring member atoms of the aromatic heterocycle include, in addition to carbon atoms, 1, 2, 3 or 4 heteroatoms selected from N, O and S as ring member atoms； and wherein the cyclic groups A are unsubstituted or substituted with 1, 2, 3 or 4 identical or different RA groups； wherein RA is halogen, cyano, di-C₁₋₆-alkylamino, C₁₋₆-alkyl, C₁₋₆-alkyloxy, C₁₋₆-alkylthio, C₁₋₆-alkylsulfinyl, C₁₋₆-alkylsulfonyl,C₂₋₆-alkenyl, C₂₋₆-alkynyl, C₃₋₈-cycloalkyl or C₃₋₈-cycloalkoxy； and wherein any of the aliphatic or cyclic portions are unsubstituted or substituted with 1, 2, 3 or 4 identical or different Rᵃ groups； wherein Rᵃ is halogen, cyano, C₁₋₆-alkyl, C₁₋₆-haloalkyl, C₁₋₆-alkoxy, C₁₋₆-haloalkoxy, C₁₋₆-alkylthio, C₁₋₆-haloalkylthio or C₃₋₈-cycloalkyl or C₁₋₄-alkoxy-C₁₋₄-alkyl； L is -C (= O) -,-C (3DS) - o -S (3DO) -In this paper, the author analyzes the characteristics of； R 1 is a single-state or saturated double cycle carbon, partially unsaturated, consisting of 3 to 10 members； or a saturated single-state or double cycle, partially unsaturated, consisting of 3 to 10 members； in this single-state or double cycle ring atom, in addition to the carbon atom, it also includes 1 or 2 carbon atoms,3 or 4 extra heteromorphic atoms selected from n or s as ring a
