1,153,582. Pesticides containing isothiazolecarboxylates. FMC CORP. 7 June, 1966 [8 June, 1965; 11 May, 1966], No. 25224/66. Heading A5E. [Also in Divisions A2, C2 and C5] A method of combating plant-infesting pathogenic organisms comprises applying an effective amount of a compound of the formula wherein R is a hydrogen or a mono- or divalent metal atom, a C 1-14 saturated' or unsaturated pnimary or secondary mono- or divalent aliphatic radical or a protonated amine; n is 1 or 2; X is an O or S atom; and R 1 is a hydrogen atom, methyl radical, or methyl derivative, to the situs of the plants. Specified methyl derivatives include the hydroxymethyl, acetoxymethyl, dimethoxymethyl, carboxaldehyde, and carbaldoxime radicals. The active compounds may be formulated as dusts, wettable powders, emulsifiable concentrates, solutions, and aerosols. The plant-infesting organisms may be controlled by applying the active compound to the seeds of the plant, to the soil either before or during planting, or during the growth of the plant, or to the growing plant. The active compounds may be used in combination with detergents as antiseptic washes and in hide and wood preservation.