The invention comprises acids of exo-cis configuration conforming to the formula <FORM:0760686/IV(b)/1> wherein R1 and R2 each represents hydrogen or an alkyl, hydroxyalkyl or cycloalkyl radical, or together represent a polymethylene or oxapolymethylene radical; and the water-soluble salts thereof. Lists of suitable R1 and R2 substituents are specified; these have preferably 1 to 12 carbon atoms. Suitable polymethylene and oxapolymethylene radicals are tetramethylene, pentamethylene, hexamethylene, and 3-oxapentamethylene radicals. Watersoluble salts are those of alkali metals, alkaline earth metals, aluminium and heavy metals; ammonium, mono-, di-, and trialkylammonium, mono-, di-, and trialkanolammonium, mixed alkylalkanolammonium, and mono-, and dicycloalkylammonium salts (lists of each being specified); and salts of heterocyclic amines such as morpholine, piperidine, pyrrolidine, and hexamethyleneimine. The compounds are prepared by reacting exo-cis-3,6-endoxohexahydrophthalic anhydride with ammonia or a primary or secondary amine in an aqueous or nonaqueous medium such as hexane, kerosene, benzene, toluene or xylene. A list of suitable amine reactants is specified. Salts are obtained by employing excess of amine reactant or by subsequent neutralization of the free acid. A list of suitable acids is specified. The examples describe the preparation of 3,6-endoxohexahydrophthalamic acid, N,N-diisopropyl- and N-butyl-3,6-endoxohexahydrophthalamic acid, butylammonium N-butyl-, dibutylammonium N,N-dibutyl-, diethylammonium N,N-diethyl-, diisopropylammonium N,N-diisopropyl-, and ammonium 3,6-endoxohexahydrophthalamate, all of exo-cis configuration.ALSO:Herbicides, defoliants and like plant response agents comprise acids of exo-cis configuration conforming to the formula: <FORM:0760686/I/1> wherein R1 and R2 each represents hydrogen or an alkyl, hydroxyalkyl or cycloalkyl radical, or together represent a polymethylene or oxapolymethylene radical; or the water-soluble salts thereof, together with at least one additional ingredient compatible therewith. Lists of suitable R1 and R2 substituents are specified; these have preferably 1 to 12 carbon atoms. Suitable polymethylene and oxapolymethylene radicals are tetramethylene, pentamethylene, hexamethylene, and 3-oxapentamethylene radicals. Specified water-soluble salts are those of sodium, potassium, calcium, strontium, magnesium, aluminium, iron, cobalt, nickel, zinc, cadmium, mercury and copper; ammonium, mono-, di-, and tri-alkylammonium, mono-, di-, and trialkanolammonium, mixed alkylalkanolammonium and mono-, and dicycloalkylammonium salts (lists of each being specified); and salts of heterocyclic amines such as morpholine, piperidine, pyrrolidine, and hexamethyleneimine. The additional ingredient may be (1) a liquid carrier in which the active ingredient is dissolved or dispersed such as water, oils of petroleum, animal, vegetable, or synthetic origin (e.g. kerosene, fuel, lubricating, soybean, linseed, castor, sperm and cod liver oils), (2) a wetting or dispersing agent such as a fatty alcohol sulphate, an aliphatic, aromatic or alkaryl sulphonate, an alkyl polyglycolether or the anologous thioether (examples are specified), (3) a solid carrier such as a clay (e.g. Fuller's earth, pyrophyllite, talc, bentonite, kieselguhr and diatomaceous earth), sulphur, volcanic ash, calcium carbonate, lime, by-product lignin, lignocellulose, flour (e.g. from wood, walnut shell, wheat, soybean, potato and cotton seed) (4) a humectant such as glycerine, diethylene glycol, ethylene glycol, polyethylene glycols, water-soluble sugars and sugar-containing mixtures (e.g. glucose, fructose, galactose, mannose, arabinose, xylose, sucrose, maltose, lactose, raffinose and trehalose), dextrins (e.g. white dextrin, canary dextrin and British gum), honey, molasses, maple syrup, maple sugar, corn syrup and other starch syrups, (5) any combination of (1), (2), (3) and (4). The resulting compositions may also include fungicides, insecticides, bactericides and other types of plant response agents. Preferred active ingredients are dimethylammonium exo-cis-N, N-dimethyl-, diethylammonium exo-cis-N, N-diethyl, and dibutylammonium exo-cis-N, N-dibutyl-3, 6-endoxohexahydrophthalamate, exo-cis-N, N-diethyl-, and exo-cis-N, N-diisopropyl-3, 6-endoxohexahydrophalanic acid. The examples describe (1) a dust comprising exo-cis-N-butyl-3, 6-endoxohexahydrophthalamic acid, talc and sodium dodecylbenzene sulphonate (2) a composition suitable for application as an aqueous dispersion comprising dimethyl-ammonium exo-cis-N, N-dimethyl-, or butyl-ammonium exo-cis-N-butyl-3, 6- endoxohexahydrophthalamate, Fuller's earth and lignin sulphonate (3) an oil-in-water emulsion prepared by stirring an aqueous solution of exo-cis-N, N-diisopropyl-3, 6-endoxohexahydrophthalamic acid and sorbitol oleate ethylene oxide with diesel oil.ALSO:Herbicides, defoliants and like plant response agents comprise acids of exo-cis configuration conforming to the formula <FORM:0760686/VI/1> wherein R1 and R2 each represents hydrogen or an alkyl, hydroxy-alkyl or cycloalkyl radical, or together represent a polymethylene or oxapolymethylene radical; or the water-soluble salts thereof, together with at least one additional ingredient compatible therewith. Lists of suitable R1 and R2 substituents are specified; these have preferably 1 to 12 carbon atoms. Suitable polymethylene and oxapolymethylene radicals are tetramethylene, pentamethylene, hexamethylene, and 3 - oxapentamethylene radicals. Specified water-soluble salts are those of sodium, potassium, calcium, strontium, magnesium, aluminium, iron, cobalt, nickel, zinc, cadmium, mercury and copper; ammonium, mono-, di-, and trialkylammonium, mono-, di-, and trialkanolammonium, mixed alkylalkanolammonium and mono-, and dicycloalkylammonium salts (lists of each being specified): and salts of heterocyclic amines such as morpholine, piperidine, pyrrolidine, and hexamethyleneimine. The additional ingredient may be (1) a liquid carrier in which the active ingredient is dissolved or dispersed such as water, oils of petroleum, animal, vegetable, or synthetic origin (e.g. kerosene, fuel, lubricating, soybean, linseed, castor, sperm and cod liver oils), (2) a wetting or dispersing agent such as a fatty alcohol sulphate, an aliphatic, aromatic or alkaryl sulphonate, an alkyl polyglycolether or the anologous thioether (examples are specified) (3) a solid carrier such as a clay (e.g. fuller's earth, pyrophyllite, talc, bentonite, kieselguhr and diatomaceous earth), sulphur, volcanic ash, calcium carbonate, lime, byproduct lignin, lignocellulose, flour, e.g. from wood, walnut shell, wheat, soybean, potato and cotton seed) (4) a humectant such as glycerine, diethylene glycol, ethylene glycol, polyethylene glycols, water-soluble sugars and sugar-containing mixtures (e.g. glucose, fructose, galactose, mannose, arabinose, xylose, sucrose, maltose, lactose, raffinose and trehalose), dextrins (e.g. white dextrin, canary dextrin and British gum), honey, molasses, maple syrup, maple sugar, corn syrup and other starch syrups (5) any combination of (1), (2), (3) and (4). The resulting compositions may also include fungicides, insecticides, bactericides and other types of plant response agents. Preferred active ingredients are dimethylammonium exocis-N, N-dimethyl-, diethylammonium exocis-N, N-diethyl, and dibutylammonium exo-cis-N, N-dibutyl-3, 6-endoxohexa-hydrophthalamate, exo-cis-N, N-diethyl-, and exo-cis-N, N-diisopropyl-3, 6-endoxohexahydrophalanic acid. The examples describe (1) a dust comprising exo-cis - N - butyl - 3, 6 - endoxohexahydrophthalamic acid, talc and sodium dodecylbenzene sulphonate (2) a composition suitable for application as an aqueous dispersion comprising dimethylammonium exo - cis - N, N - dimethyl -, or butylammonium exo-cis-N-butyl-3, 6- endoxohexahydrophthalamate, fuller's earth and lignin sulphonate (3) an oil-in-water emulsion prepared by stirring an aqueous solution of exo-cis-N, N-diisopropyl-3, 6-endoxohexahydrophthalamic acid and sorbitol oleate ethylene oxide with diesel oil.