1. A plant disease control composition comprising a carboxamide compound represented by the formula (I): wherein R 1 represents a hydrogen atom or a methyl group, and R 3 represents a methyl group, a difluoromethyl group or a trifluoromethyl group and one or more QoI compounds selected from group (A) consisting of dimoxystrobin, azoxystrobin, fluoxastrobin, pyraclostrobin, kresoxim methyl, picoxystrobin, trifloxystrobin and N-methyl-alpha-methoxyimino-2 - [(2,5-dimethylphenoxy) methyl] phenylacetamide. The plant disease control composition of claim 1, wherein the weight ratio of the carboxamide compound to the QoI compound (s) is 0.1 / 1 to 10/1 for the carboxamide compound / QoI compound (s) ratio. A method for controlling a plant disease that includes the step of treating a plant or soil where a plant grows, an effective amount of a carboxamide compound represented by the formula (I): in which R 1 represents a hydrogen atom or a methyl group and R 3 represents a methyl group, a difluoromethyl group or a trifluoromethyl group and one or more QoI compounds selected from the group (A) consisting of dimoxystrobin , azoxystrobin, fluoxastrobin, pyraclostrobin, kresoxim methyl, picoxystrobin, trifloxystrobin and N-methyl-alpha-methoxyimino-2 - [(2,5-dimethylphenoxy) methyl] phenylacetamide. The plant disease control method according to claim 3, wherein the weight ratio of the carboxamide compound to the QoI compound (s) is 0.1 / 1 to 10/1 for the carboxamide compound / QoI compound (s) ratio. A method for controlling a plant disease according to claim 3 or 4, wherein the plant or soil where the plant grows represented by the formula (I): in which R 1 represents a hydrogen atom or a methyl group and R 3 represents a methyl group, a difluoromethyl group or a trifluoromethyl group and one or more QoI compounds selected from the group (A) consisting of dimoxystrobin, azoxystrobin, fluoxastrobin, pyraclostrobin, kresoxim methyl, picoxystrobin, trifloxystrobin and N-methyl-al
