1. A synergistic antimicrobial composition comprising (a) flumetsulam and (b) an isothiazolone-based biocide selected from the group consisting of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 2-n-octyl -4-isothiazolin-3-one and N-n-butyl-1,2-benzisothiazolin-3-one, where the mass ratio of flumetsulam to 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one is from 15: 1 to 1:15, the mass ratio of flumetsulam to 2-n-octyl-4-isothiazolin-3-one is from 7: 1 to 1: 5 and the mass ratio of flumetsulam to N-n-butyl-1,2- benzisothiazolin-3-one is from 15: 1 to 1: 15.2. The composition of claim 1, wherein the isothiazolone-based biocide is 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, and the weight ratio of flumetsulam to 4,5-dichloro-2-n-octyl- 4-isothiazolin-3-one is from 10: 1 to 1: 10.3. The composition of claim 1, wherein the isothiazolone-based biocide is 2-n-octyl-4-isothiazolin-3-one, and the weight ratio of flumetsulam to 2-n-octyl-4-isothiazolin-3-one is from 5: 1 up to 1: 3.4. The composition of claim 1, wherein the isothiazolone-based biocide is Nn-butyl-1,2-benzisothiazolin-3-one, and the weight ratio of flumetsulam to Nn-butyl-1,2-benzisothiazolin-3-one is from 10: 1 to 1: 10.5. A synergistic antimicrobial composition comprising (a) diclosulam and (b) an isothiazolone-based biocide selected from the group consisting of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one and 2-n-octyl-4 -isothiazolin-3-one, where the mass ratio of diclosulam and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one is from 7: 1 to 1: 3, and the mass ratio of diclosulam and 2-n- octyl-4-isothiazolin-3-one is from 7: 1 to 1: 1.5 or from 1: 3 to 1: 7.6. The composition of claim 5, wherein the isothiazolone-based biocide is 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, and the weight ratio1. Синергетическая противомикробная композиция, включающая (а) флуметсулам и (b) биоцид на основе изотиазолона, выбранный из группы, включающей 4,5-дихлор-2-н-октил-4-изотиазолин-3-он, 2-н-октил-4-изотиазолин-3-он и N-н-бутил-
