1. A composition for controlling plant diseases comprising a carboxamide compound represented by the formula (I): [Chem. 1] wherein R is a hydrogen atom or a methyl group, iRpredstavlyaet a methyl group, a difluoromethyl group or trifluoromethyl group, and one or more dithiocarbamate compounds selected from the group (A), consisting of mancozeb, maneb, thiram and tsineba.2. A composition for controlling plant diseases according to claim 1, wherein the weight ratio of the carboxamide compound to dithiocarbamate compound (s) is from 0.01 / 1 to 1/1 carboxamide compound / dithiocarbamate compound (s) .3. A method for controlling plant diseases, which comprises the step of treating a plant or soil where a plant grows with an effective amount of the carboxamide compound represented by the formula (I): [Chem. 2] wherein R represents a hydrogen atom or a methyl group, iRpredstavlyaet a methyl group, a difluoromethyl group or trifluoromethyl group, and one or more dithiocarbamate compounds selected from the group (A), consisting of mancozeb, maneb, thiram and tsineba.4. A method for controlling plant diseases according to claim 3, wherein the weight ratio of the carboxamide compound to dithiocarbamate compound (s) is from 0.01 / 1 to 1/1 carboxamide compound / dithiocarbamate compound (I) .5. A method for controlling plant diseases according to claim 3 or 4, wherein the plant or the soil where the plant grows, or wheat are soil where it grows wheat respectively.1. Композиция для борьбы с заболеваниями растений, включающая карбоксамидное соединение, представленное формулой (I):[Хим. 1]где R1 представляет собой атом водорода или метильную группу, иR2 представляет собой метильную группу, дифторметильную группу или трифторметильную группу,и одно или более дитиокарбаматных соединений, выбранных из группы (A), состоящей из манкозеба, манеба, тирама и цинеба.2. Композиция для борьбы с заболеваниями растений по п.1, где массовое соотношение карбоксамидного соединения к дитиокарбама
