Abstract: An imidazolidinedione compound of the formula: ##STR1## wherein X is a chlorine atom or a bromine atom, Y is an oxygen atom or a sulfur atom, and R.sub.1 and R.sub.2 are each a C.sub.1 -C.sub.4 alkyl group, a C.sub.1 -C.sub.4 alkoxy group, a C.sub.1 -C.sub.4 alkylthio group, an ar(C.sub.1 -C.sub.4)alkylthio group, a C.sub.1 -C.sub.4 alkoxy(C.sub.2 -C.sub.4)alkoxy group, a phenyl group, a phenoxy group, a C.sub.1 -C.sub.4 alkylthiophenoxy group, a C.sub.1 -C.sub.8 alkylamino group, a C.sub.2 -C.sub.8 alkenylamino group or a cyano(C.sub.1 -C.sub.4)alkylamino group, which is useful as an agricultural chemical such as insecticides, acaricides, nematocides and/or fungicides with high safety to mammalian animals and human beings.

Abstract: 1-Branched-alkylcarbonyl-3-(3,5-dihalophenyl)imidazolidine-2,4-diones of the formula: ##STR1## wherein X is a chlorine or bromine atom and R is a C.sub.3 -C.sub.5 branched alkyl group, which show high fungicidal activities without any material toxicity to mammals and plants and which can be produced by reacting the corresponding 1-unsubstituted compound with a branched alkanecarboxylic acid or a reactive derivative thereof.

Abstract: 1-Cycloalkylcarbonyl-3-(3,5-dihalophenyl)imidazolidine-2,4-diones of the formula: ##STR1## wherein X is a chlorine or bromine atom, R.sub.1 is a C.sub.3 -C.sub.6 cycloalkyl, tetramethylcyclopropyl, 2,2-dimethyl-3-isobutenylcyclopropyl or 2,2-dimethyl-3-dichlorovinylcyclopropyl group and R.sub.2 and R.sub.3 are individually a hydrogen atom or a methyl group, which show high fungicidal activities without any material toxicity to mammals and plants and which can be produced by reacting the corresponding 1-unsubstituted compound with a cycloalkanecarboxylic acid or a reactive derivative thereof.

Abstract: N-(3,5-Dihalophenyl)-.alpha.-spirocycloalkanesuccinimides of the formula: ##STR1## wherein X is a chlorine or bromine atom and R is a C.sub.3 -C.sub.6 alkylene group, which show high fungicidal activities without any material toxicity to mammals and plants and which can be produced by reacting the corresponding .alpha.-spirocycloalkanesuccinic acid or its anhydride with 3,5-dichloroaniline or 3,5-dibromoaniline.

Abstract: 3-(3',5'-Dihalophenyl)-1-sulfenylimidazolidine-2,4-diones of the formula: ##STR1## wherein X is a chlorine atom or a bromine atom, Y.sub.1, Y.sub.2 and Y.sub.3 are each a chlorine atom or a fluorine atom and R.sub.1 and R.sub.2 are individually a hydrogen atom or a methyl group, which show high microbicidal activities against various fungi without any material toxicity to mammals and plants and can be produced by reacting the corresponding 1-unsubstituted compound with a sulfenyl halide.

Abstract: 3-(3' -Dihalophenyl)-1-sulfonylimidazolidine-2,4-5'-diones of the formula: ##STR1## wherein X is a halogen atom, R.sub.1 is a C.sub.1 -C.sub.12 alkyl group, a C.sub.2 -C.sub.4 alkenyl group or a halogenated C.sub.1 -C.sub.4 alkyl group having 1 to 3 halogen atoms, and R.sub.2 and R.sub.3 are individually a hydrogen atom or a methyl group, which show high microbicidal activities against various fungi and bacteria without any material toxicity to mammals and which plants and can be produced by reacting the corresponding 1-unsubstituted compound with a sulfonyl halide.