Use of Benzothiadiazoles

The present invention relates to the use of benzothiadiazoles as a protection against the effects of abiotic stress on plants.

Abiotic stresses, such as drought, salt or extreme temperatures limit crop production significantly. For example, abiotic stress often causes reductions in overall crop yield or decreases in the quality of plants. Crop losses and crop yield losses of major agricultural crops by abiotic stress represent a significant economic factor. Especially temperature stress such as chill, frost or heat and effects such as dryness or drought are major limiting factors of plant growth and productivity.

Plants often are exposed to cold, for example to temperatures below freezing after sowing. Freezing temperatures often cause plants to stall or suffer enduring damages. Particularly with regard to agricultural crop damages due to frost often cause immense losses in agriculture.

Protection to avoid damages caused by freezing temperatures for example by protective fleece or foil is costly and expensive.

Document EP 0 313 512 A2, the entire contents of which is herein incorporated by reference, discloses benzothiadiazoles for the immunisation of healthy plants against pathogens.

Surprisingly it was found that benzothiadiazoles furthermore can be used to protect plants against the effects of abiotic stress, especially of frost and drought.

UD 40102 / SAM: AL

Therefore, the object underlying the present invention was to provide a novel use of benzothiadiazoles.

The problem is solved by the use of compounds according to general formula (I) as given as follows and/or their salts and/or esters for improving tolerance of a plant against abiotic stress:

wherein:

X is selected from the group comprising hydrogen, halogen, hydroxy, methyl, methoxy and/or COOH;

Y is selected from the group comprising hydrogen, halogen, SO ₃ H, nitro, hydroxy, and/or amino;

Z is selected from the group comprising cyano and/or -CO-A;

A is selected from the group comprising UR, N(R ¹ )R ² and/or U ¹ NC=C) _n (R^R ⁴ ;

U is selected from the group comprising oxygen and/or sulfur;

U ¹ is selected from the group comprising oxygen and/or -N(R ⁵ )-;

R is selected from the group comprising hydrogen, d-Cg-alkyl, d-Cg-alkyl that is substituted by halogen, cyano, nitro, hydroxy, U-Ci-C3-alkyl or by C2-C4- dialkylamino or is interrupted by the CO group, (T)-COOH or (T)COOCi-C ₄ - alkyl, Cs-Cβ-alkenyl, halo-substituted Cs-Cβ-alkenyl, Cs-Cβ-alkynyl, halo-

substituted Cs-Cβ-alkynyl, (T) _n C3-C8-cycloalkyl, and/or a group selected from the group comprising

(T) _n -napht, (T) _n -Si(Ci-C8-alkyl)3, or (T) _n -W;

X ^a , X ^b and X ^c are each independently of each other selected from the group comprising hydrogen, halogen, hydroxy, cyano, COOH, Ci-C3-alkyl-OOC, C ₁ - C ₄ -alkyl, Ci-C ₄ -alkoxy, and/or Ci-C ₂ -haloalkyl having up to 5 halogen atoms, particularly fluorine atoms; or

X ^a is selected from the group comprising Ci-C2-halogenalkoxy having up to 5 halogen atoms, nitro, dimethylamino, phenyl, phenyloxy, benzyloxy, sulfamoyl and X ^b and X ^c are both hydrogen; or

X ^a is selected from the group comprising phenyl, phenyloxy and/or benzyloxy and X ^b is selected from the group comprising halogen and/or methyl and X ^c is hydrogen; or

X ^a , X ^b and X ^c together are 4 or 5 fluorine atoms; napht is a naphthyl radical that is unsubstituted or is substituted by halogen, methyl, methoxy or by nitro;

W is a 5- to 7-membered saturated or unsaturated heterocycle having from 1 to 3 hetero atoms selected from the group comprising O, N and S that is unsubstituted or is substituted by halogen, trifluoromethyl, cyano, Ci-C2-alkyl or by a C ₁ -C ₂ - alkoxycarbonyl-C2-C4-alkyleneimino radical, or is a monosaccharide radical;

- A -

T is a bridge member selected from the group comprising -CH ₂ -, -CH ₂ CH ₂ -, -CH(CH ₃ )-, -CCH ₃ (CH ₃ )-, -CH ₂ CH ₂ CH ₂ -, and/or -CH ₂ CH ₂ O-;

R ¹ is selected from the group comprising hydrogen, Ci-Cs-alkyl, Ci-Cs-alkyl interrupted by an oxygen or sulfur atom, Ci-Cs-alkyl substituted by halogen, cyano, COOH or by Ci-C ₂ -alkyl-OOC, Ci-Cs-alkyl interrupted by an oxygen or sulfur atom and substituted by halogen, cyano, COOH or by Ci-C ₂ -alkyl-OOC, C ₃ -C ₅ -alkenyl, C ₃ -C ₅ -alkenyl substituted by Ci-C ₃ -alkyl-OOC, C ₃ -C ₅ -alkynyl, C ₃ -C ₅ -alkynyl substituted by Ci-C ₃ -alkyl-OOC, (T) _n -C ₃ -C ₆ -cycloalkyl, (T) _n -C ₃ - Cβ-cycloalkyl substituted by Ci-C ₃ -alkyl-OOC, (T) _n -phenyl and/or (T) _n -phenyl substituted in the phenyl moiety by halogen, hydroxy, methyl, methoxy, CF ₃ , cyano or by COOH;

R ² is selected from the group comprising hydrogen, hydroxy, Ci-C ₃ -alkyl, Ci-C ₃ - alkyl substituted by cyano or Ci-C ₃ -alkoxy, Ci-C4-alkoxy, a 3- to 6-membered saturated or unsaturated heterocycle containing O, N or S as hetero atoms;

R ¹ and R ² together with the atom to which they bond are a heterocycle W;

R ³ is selected from the group comprising hydrogen, cyano, Ci-Cβ-alkyl, phenyl, phenyl substituted by halogen, hydroxy, methyl, methoxy or COOH, and/or a heterocycle W;

R ⁴ is selected from the group comprising hydrogen, Ci-Cβ-alkyl, CONH ₂ , CONH-

CONH-Ci-C ₃ -alkyl, Ci-C ₃ -alkanoyl, Ci-C ₃ -alkanoyl substituted by halogen or by Ci-C ₃ -alkoxy, C ₃ -Cs-alkenoyl and/or C ₃ -Cs-alkenoyl substituted by halogen or by Ci-C ₃ -alkoxy;

R ³ and R ⁴ together with the atom to which they bond are a heterocycle W or a carbocyclic ring W;

W is a carbocyclic radical having from 3 to 7 ring carbon atoms;

R ⁵ is selected from the group comprising hydrogen and/or methyl;

R ⁶ is selected from the group comprising hydrogen and/or Ci-C ₄ -alkyl; n is O or 1.

Furthermore, the invention relates to a composition for improving tolerance of a plant against abiotic stress, comprising a compound applicable in accordance with the invention as an active ingredient.

Preferred embodiments of compounds applicable according to the invention are given in the dependant claims.

Surprisingly it was found that already a singular application of a compound applicable according to the invention can improve the tolerance of a plant against abiotic stresses, especially against frost or drought. Particularly, a singular application of a compound applicable according to the invention already can provide a tolerance of the plant against cold lasting several days, weeks or months.

The term "plants" according to the invention refers to all genera and species of higher and lower plants of the plant kingdom. The term "plants" includes the mature plants, seed, shoots and seedlings, and also parts, such as tubers, seeds or fruits, plant organs, tissues, protoplasts, callus and other cultures, for example cell cultures, derived therefrom. The term "mature plants" refers to plants at any developmental stage beyond that of the seedling. The term "seedling" refers to a young immature plant at an early developmental stage.

Abiotic stress acting on a plant are for example temperature effects such as chill, frost or heat, effects of water such as dryness, drought, wet conditions, or chemical load such as lack of or excess of nutrients, mineral salts, heavy metals, nitrogen or oxygen and/or UV radiation.

In preferred embodiments the abiotic stress is selected from the group comprising drought stress, salinity stress, heat stress, cold stress, frost stress, low nitrogen conditions, low oxygen conditions, low nutrient conditions and/or UV radiation.

It is an surprising advantage that the application of compounds according to general formula (I) can improve the tolerance of plants against abiotic stress factors, preferably against abiotic stress selected from the group comprising drought stress, salinity stress, cold or heat stress, and/or frost stress.

Under an improved tolerance of a plant against abiotic stress, such as cold, particularly is to be understood an improved stability or resistance against abiotic stress, such as cold. An improved resistance or tolerance against cold can provide the advantage that damages to a plant caused by frost or cold can be reduced or inhibited.

Without being bound to a specific theory it is assumed that the compounds applicable according to the invention can activate endogenous defence mechanisms of a plant against abiotic stress factors such as cold.

Such resistance against stress factors, such as cold, particularly can be understood as an induction of a tolerance against stress factors, such as cold, in a plant.

It is especially advantageous that such induction of a tolerance against cold particularly can be a tolerance of a plant against frost. Temperature ranges in which the compounds applicable according to the invention can provide and/or activate a protection of plants against cold are for example in the range from > - 14°C to < 10 ⁰ C, preferably in the range from > - 14 ⁰ C to < 4 ⁰ C, more preferably in the range from > - 14 ⁰ C to < 0 ⁰ C.

Moreover, it was surprisingly found that an application of a compound applicable according to the invention can provide a tolerance of a plant against drought. For example, it was found that a singular application of a compound applicable according to the invention already can provide a plant surviving a drought period of several weeks.

The term "hetero atoms" according to the invention also includes elements other than N, O and S, for example Si or P.

The term "halogen" according to the invention is to be understood as meaning fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine.

The term "alkyl" according to the invention is to be understood as meaning straight-chain or branched alkyl groups. Preferred alkyl groups are selected from the group comprising methyl, ethyl and the isomers of propyl, butyl, pentyl, hexyl, heptyl or octyl, such as, for example, isopropyl, isobutyl, tert.-butyl, sec. -butyl and/or isopentyl.

The term "cycloalkyl" according to the invention is to be understood as meaning for example cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

The term "alkenyl" according to the invention is to be understood as meaning propen-1-yl, allyl, buten-1-yl, buten-2-yl or buten-3-yl, and chains having several double bonds.

The term "alkynyl" according to the invention is to be understood as meaning for example propyn-2-yl, butyn-1-yl, butyn-2-yl, pentyn-4-yl, preferably propargyl.

The term "heterocycles" according to the invention is to be understood as being, for example furan, tetrahydrofuran, thiophene, tetrahydropyran, pyrrole, pyrrolidine, imidazole, 1,2,4- triazole, piperidine, pyridine, pyrimidine, morpholine or azacyclo heptane. Preferred heterocycles are selected from the group comprising furan-2-yl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydropyran-2-yl, l,3-dioxolan-5-yl, pyrrol- 1-yl, pyrrol-2-yl, pyrrolidin-1-yl, isoxazol-3-yl, isoxazol-4-yl, l,2-di-thiazolin-5-yl, imidazol-1-yl, 1,2,4- triazol-1-yl, 1,3,4-triazol-l-yl, thiophen-2-yl, piperidin-1-yl, piperidin-4-yl, pyridin-2-yl,

pyridin-3-yl, pyridin-4-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrimidin-5-yl, morpholin-1-yl, azacycloheptan-1-yl and/or benzo-l,2,3-thiadiazol-7'-yl.

The term "monosaccharide radical" is to be understood as being, for example, glucopyranosyl, galactopyranosyl, allofuranosyl or mannityl, the OH groups being free or acetylated or etherifϊed by methyl, benzyl or by isopropylidenyl. Of the radicals mentioned, the diisopropylidenyl derivatives are preferred, whilst of these in turn the following radicals selected from the group comprising diacetone-D-glucosidyl, 1,2,3,4-di-O-isopropyl-idene-D- galactopyranos-6-yl, 1 ,2,5,6-di-O-isopropylidene-D-mannit-3-yl, 1 ,2,5,6-di-O- isopropylidene-alpha-D-allofuranos-3-yl, D-glucofuranos-3-yl, D-galacto-pyranos-6-yl, D- mannit-3-yl, D-allofuranos-4-yl, mannopyranos-1-yl, 2-methyl-D-glucosid-6-yl, 1,2,5,6- tetraacetyl-D-galactopyranos-3-yl and/or 2,3,5-tribenzylribofuranos-l-yl are especially preferred.

In the case where U is oxygen or sulfur, preferred salts of the compounds according to general formula (I) comprise salts of the phytophysio logically tolerable 7-carboxylic acid with primary, secondary or tertiary amines or with inorganic bases.

Suitable cationic radicals for the compounds applicable according to the invention are for example metals and organic bases. Alkali metals and alkaline earth metals are advantageous as metals, but any others may also come into consideration. Suitable organic bases are amines, especially having aliphatic, aromatic, araliphatic and/or cycloaliphatic radicals.

Preferred cationic groups are for example cations of alkali metals, preferably selected from the group comprising Li ⁺ , Na ⁺ and/or K ⁺ , or cations of alkali earth metals, preferably selected from the group comprising Ca ²⁺ and/or Mg ²⁺ . Further preferred cationic groups are for example quaternary ammonium salts which contain at least one nitrogen atom having four substitutes, wherein the substitutes preferably are selected from the group comprising H

and/or Ci-Cs-alkyl radical. Examples for ammonium cations are selected from the group comprising tetramethylammonium, tetraethylammonium, and/or tetra-n-butylammonium.

Suitable bases or compounds having basic character are inorganic bases or base formers, for example selected from the group comprising hydroxides, carbonates and/or hydrogen carbonates of alkali metals and alkaline earth metals, preferably LiOH, NaOH, KOH, Mg(OH) ₂ or Ca(OH) ₂ , and also NaHCO ₃ , KHCO ₃ , Na ₂ CO ₃ or K ₂ CO ₃ .

Salt-forming amines preferably are selected from the group comprising trimethylamine, triethylamine, tripropylamine, tributylamine, tribenzylamine, tricyclohexylamine, triamylamine, trihexylamine, N,N-dimethylaniline, N,N-dimethyltoluidine, N,N-dimethyl-p- aminopyridine, N-methylpyrrolidine, N-methylpiperidine, N-methylpyrrolidine, N- methylimidazole, N-methylpyrrole, N-methylmorpholine, N-methylhexamethyleneimine, pyridine, quinoline, alpha-picoline, beta-picoline, isoquinoline, pyrimidine, acridine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, quinoxaline, N- propyldiisopropylamine, N,N-dimethylcyclohexylamine, 2,6-lutidine, 2,4-lutidine, triethylenediamine and/or heterocyclic amines of the morpholine type.

Preferred compounds are selected from the group comprising benzo- 1,2,3- thiadiazolecarboxylic acid, benzo-l,2,3-thiadiazolethiocarboxylic acid, cyanobenzo- 1,2,3- thiadiazole, Benzo-l,2,3-thiadiazolecarboxylic acid amide, benzo-l,2,3-thiadiazolecarboxylic acid hydrazide, benzo-l,2,3-thiadiazole-7-carboxylic acid, benzo- 1,2, 3-thiadiazole-7- thiocarboxylic acid, 7-cyanobenzo-l,2,3-thiadiazole, benzo- l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester, benzo-l,2,3-thiadiazole-7-carboxylic acid amide, benzo- 1,2,3- thiadiazole-7-carboxylic acid hydrazide, alkyl benzo- 1,2,3-thiadiazolecarboxylate in which the alkyl group contains one to six carbon atoms, methyl benzo- 1,2,3-thiadiazo le-7- carboxylate, n-propyl benzo-l,2,3-thiadiazole-7-carboxylate, benzyl benzo- 1,2,3-thiadiazo Ie- 7-carboxylate and/or benzo- 1,2,3-thiadiazo le-7-carboxylic acid sec-butyl hydrazide.

In preferred embodiments of the compounds applicable according to the invention the substituents X and Y are hydrogen. In further preferred embodiments of the compounds applicable according to the invention the substituent Z is a group COA. In another preferred embodiment of the compounds applicable according to the invention the substituent A is a group UR, wherein U is selected from the group comprising oxygen and/or sulphur. Preferably, U is sulphur.

In further preferred embodiments of the compounds applicable according to the invention the substituent R is selected from the group comprising hydrogen, Ci-Cs-alkyl, Ci-Cs-alkyl that is substituted by halogen, or by Ci-C3-alkoxy, Cs-Cβ-alkenyl, Cs-Cβ-alkenyl substituted by halogen, Cs-Cβ-alkynyl, Cs-Cβ-alkynyl substituted by halogen, benzyl, halo-substituted benzyl, and/or benzylmethoxy.

In especially preferred embodiments of the compounds applicable according to the invention is:

X and Y hydrogen,

Z COA,

A UR,

U sulfur,

R selected from the group comprising hydrogen, d-Cg-alkyl, d-Cg-alkyl that is substituted by halogen or by Ci-C ₃ -alkoxy, Cs-Cβ-alkenyl, Cs-Cβ-alkenyl substituted by halogen, Cs-Cβ-alkynyl, Cs-Cβ-alkynyl substituted by halogen, benzyl, halo-substituted benzyl, and/or benzylmethoxy.

In further especially preferred embodiments of the compounds applicable according to the invention the group COA is a group C0S(Ci-C ₈ -alkyl).

In especially preferred embodiments of the compounds applicable according to the invention the compounds are selected from the group comprising benzo-l,2,3-thiadiazole-7-carboxylic acid, benzo-l,2,3-thiadiazole-7-thiocarboxylic acid and/or their Ci-Cs-alkyl esters.

In further preferred embodiments of the compounds applicable according to the invention the d-Cg-alkyl ester is selected from the group comprising methyl ester, ethyl ester, isopropyl ester, n-butyl ester, tert-butyl ester, n-pentyl ester, n-hexyl ester, n-heptyl ester and/or n-octyl ester. Preferred are Ci-C ₄ -alkyl esters, particularly selected from the group comprising methyl ester, ethyl ester, isopropyl ester and/or tert-butyl ester. Especially preferred are methyl ester and ethyl ester.

In further especially preferred embodiments of the compounds applicable according to the invention the compounds are selected from the group comprising benzo-l,2,3-thiadiazole-7- thiocarboxylic acid and/or its S-Ci-Cs-alkyl esters.

In further especially preferred embodiments of the compounds applicable according to the invention the S-Ci-Cs-alkyl esters are S-Ci-C4-alkyl esters selected from the group comprising S-methyl ester, S-ethyl ester, S-isopropyl ester and/or S-tert-butyl ester. Especially preferred are S-methyl ester and S-ethyl ester.

In especially preferred embodiments of the compounds applicable according to the invention the compound is benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester.

A particularly preferred applicable compound has a structure according to general formula (II) as given as follows:

Preferred plants are selected from the group comprising cereals, beet, pomes, drupes and soft fruit, leguminous plants, oil plants, cucumber plants, fibre plants, citrus fruit, vegetables, lauraceae, or plants such as maize, tobacco, nuts, coffee, sugar cane, tea, vines, hops, bananas and natural rubber plants, and/or ornamentals.

Preferred cereals are selected from the group comprising wheat, barley, rye, oats, rice, spelt, flax seed, sorghum and/or related crops. Preferred beet are selected from the group comprising sugar beet and/or fodder beet. Preferred pomes, drupes and soft fruit are selected from the group comprising apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries, blueberries and/or blackberries. Preferred leguminous plants are selected from the group comprising beans, lentils, peas, and/or soybeans. Preferred oil plants are selected from the group comprising rape, mustard, poppy, olives, sunflowers, coconut, castor oil plants, cocoa beans, and/or groundnuts. Preferred cucumber plants are selected from the group comprising cucumber, marrows, and/or melons. Preferred fibre plants are selected from the group comprising cotton, flax, hemp and/or jute. Preferred citrus fruit are selected from the group comprising oranges, lemons, grapefruit, and/or mandarins. Preferred vegetables are selected from the group comprising spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes and/or paprika. Preferred lauraceae are selected from the group comprising avocados, cinnamon and/or camphor. Preferred ornamentals are selected from the group comprising flowers, shrubs, deciduous trees and/or conifers.

In preferred embodiments the plants are selected from the group comprising cereals, fruit plants and/or vegetables.

Agricultural crops which are particularly suitable target crops for the application of the compounds according to the invention are selected from the group comprising cucumbers, tobacco, vines, rice, cereals, for example wheat, pears, pepper, potatoes, tomatoes and/or apples.

Further agricultural crops which are particularly suitable target crops for the application of the compounds applicable according to the invention are selected from the group comprising cotton, vegetables for example cucumber or beans, barley, grass, oats, coffee, maize, fruit plants, rice, rye, soybeans, vines, wheat, ornamentals, sugar cane and/or a plurality of seeds.

Particularly suitable cereals are selected from the group comprising barley, oats, rye and/or wheat.

Particularly suitable fruit plants are selected from the group comprising fruit trees, vines, soft fruit, berries, strawberries, blueberries and/or raspberries

Particularly suitable fruit trees are selected from the group comprising apple trees, pear trees, cherry trees, plum trees, prune plum trees, apricot trees and/or peach trees.

The present invention relates also to the use of the compounds applicable according to the invention to manufacture a composition particularly a composition for improving tolerance of a plant against abiotic stress, preferably for improving frost tolerance and/or tolerance against drought.

In preferred embodiments said composition comprises as an active ingredient a compound applicable according to the invention, particularly selected from the group comprising benzo- l,2,3-thiadiazole-7-thiocarboxylic acid and/or its S-Ci-Cs-alkylesters.

In particularly preferred embodiments said composition comprises as an active ingredient benzo-l,2,3-thiadiazole-7-thiocarboxylic acid and/or its S-Ci-Cs-alkylesters.

In especially preferred embodiments said composition comprises as an active ingredient benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester.

In preferred embodiments said composition is formulated as a liquid, gel or solid form formulation.

The compounds according to general formula (I) are normally applied in the form of compositions and can be applied to the plant or to the surrounding thereof, simultaneously or in succession, with further compounds. These further compounds can be fertilisers or micronutrient donors or other preparations that influence plant growth. They can also be selective herbicides, insecticides, fungicides, bactericides, nematicides, molluscicides or mixtures of several of these preparations, if desired together with further carriers, surfactants or application-promoting adjuvants customarily employed in the art of formulation.

Suitable carriers and adjuvants can be solid or liquid and correspond to the substances ordinarily employed in formulation technology, e.g. natural or regenerated mineral substances, solvents, dispersants, wetting agents, tackifϊers, thickeners, binders or fertilisers.

A preferred method of applying a compound according to general formula (I), or an agrochemical composition which contains at least one of said compounds, is foliar application. However, the compounds according to general formula (I) can also penetrate the

plant through the roots via the soil (systemic action) if the locus of the plant is impregnated with a liquid formulation, or if the compounds are applied in solid form to the soil, e.g. in granular form (soil application). The compounds according to general formula (I) may, however, also be applied to seeds (coating) by impregnating the seeds either with a liquid formulation containing a compound according general formula (I), or coating them with a solid formulation (dressing). Furthermore, in some cases other methods of application may be possible, for example the specific treatment of the plant stem or buds.

The compounds according to general formula (I) are used in unmodified form or, preferably, together with the adjuvants conventionally employed in the art of formulation. For this purpose compounds according to general formula (I) are formulated in known manner e.g. into emulsifϊable concentrates, coatable pastes, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granulates, and also encapsulations in e.g. polymer substances. As with the nature of the compositions, the methods of application, such as spraying, atomising, dusting, scattering, coating or pouring, are chosen in accordance with the intended objectives and the prevailing circumstances.

Advantageous rates of application are normally from 30 g to 5 kg of the compound applicable according to the invention per hectare, preferably from 100 g to 2 kg compound per hectare, most preferably from 100 g to 600 g compound per hectare.

The formulations, i.e. the compositions, preparations or mixtures containing the compound according to general formula (I) as active ingredient and, where appropriate, a solid or liquid adjuvant, are prepared by homogeneously mixing and/or grinding the compound with extenders, e.g. solvents, solid carriers and, where appropriate, surface-active compounds (surfactants).

Suitable solvents are for example aromatic hydrocarbons, preferably the fractions containing 8 to 12 carbon atoms, e.g. xylene mixtures or substituted naphthalenes, phthalates such as dibutyl phthalate or dioctyl phthalate, aliphatic hydrocarbons such as cyclohexane or paraffins, alcohols and glycols and their ethers and esters, such as ethanol, ethylene glycol, ethylene glycol monomethyl or monoethyl ether, ketones such as cyclohexanone, strongly polar solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethylformamide, as well as vegetable oils or epoxidised vegetable oils, such as epoxidised coconut oil or soybean oil; or water.

The solid carriers used e.g. for dusts and dispersible powders, are normally natural mineral fillers such as calcite, talcum, kaolin, montmorillonite or attapulgite. In order to improve the physical properties it is also possible to add highly dispersed silicic acid or highly dispersed absorbent polymers. Suitable granulated adsorptive carriers are porous types, for example pumice, broken brick, sepiolite or bentonite, and suitable nonsorbent carriers are, for example, calcite or sand. In addition, a great number of pregranulated materials of inorganic or organic nature can be used, e.g. especially dolomite or pulverised plant residues. Particularly advantageous application-promoting adjuvants are also natural (animal or vegetable) or synthetic phospholipids of the series of the cephalins and lecithins.

Depending on the nature of the compound according to general formula (I) to be formulated, suitable surface-active compounds are non-ionic, cationic and/or anionic surfactants having good emulsifying, dispersing and wetting properties. The term "surfactants" is also understood as comprising mixtures of surfactants.

Cationic surfactants are preferably quaternary ammonium salts which contain, as N- substituent, at least one Cs -C22 alkyl radical and, as further substituents, unsubstituted or halogenated lower alkyl, benzyl or hydroxy-lower alkyl radicals.

The term "lower alkyl" according to the invention is to be understood as meaning particularly C ₁ -C ₈ alkyl radicals.

Both so-called water-soluble soaps and also water-soluble synthetic surface-active compounds are suitable anionic surfactants.

Suitable soaps are the alkali metal salts, alkaline earth metal salts or unsubstituted or substituted ammonium salts of higher fatty acids Of CiO-C ₂₂ , e.g. the sodium or potassium salts of oleic or stearic acid or of natural fatty acid mixtures which can be obtained e.g. from coconut oil or tallow oil.

Synthetic surfactants that may be used are especially fatty alcohol sulfonates, fatty alcohol sulfates, sulfonated benzimidazole derivatives or alkylsulfonates. The fatty alcohol sulfonates or sulfates are usually in the form of alkali metal salts, alkaline earth metal salts or unsubstituted or substituted ammonium salts and contain a Cs-C ₂₂ alkyl radical.

Non- ionic surfactants are preferably polyglycol ether derivatives of aliphatic or cycloaliphatic alcohols, saturated or unsaturated fatty acids and alkylphenols, said derivatives containing 3 to 30 glycol ether groups and 8 to 20 carbon atoms in the (aliphatic) hydrocarbon moiety and 6 to 18 carbon atoms in the alkyl moiety of the alkylphenols.

The compositions may also contain further auxiliaries such as stabilisers, antifoams, viscosity regulators, binders, tackifϊers as well as fertilisers or other active ingredients for obtaining special effects.

Agrochemical compositions preferably contain 10 % by weight to 90 % by weight, preferably 30 % by weight to 80 % by weight, particularly 50 % by weight to 60 % by weight, relating to the total weight of the agrochemical composition, of a compound according to formula (I).

The present invention relates also to a method for improving the resistance of a plant against abiotic stress, preferably for improving frost tolerance and/or tolerance against drought, wherein a compound according applicable to the invention is administered as an active ingredient to a plant and/or its surrounding.

In preferred embodiments of said method benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S- methyl ester is administered as an active ingredient to a plant and/or its surrounding.

The Examples which follow serve to illustrate the invention in more detail but do not constitute a limitation thereof.

Terms denoting genes and botanical names, as used herein, are represented in italics.

Example 1

Determination of tolerance against frost of thale cress after application of benzo- 1,2,3- thiadiazole-7-thiocarboxylic acid-S-methyl ester

About 300 seeds (accession Columbia-0) each of the herbaceous plant thale cress (botanical name: Arabidopsis thaliana) were distributed on potting soil (392 cm ³ , potting soil of Balster, Frόndenberg, Germany) in flower pots (7x7x 8cm, Gόttinger). Germination of the seeds was initiated by a stratification of 2 days at 4°C in the dark. Following, the plants were grown at 20 ⁰ C, 65 % relative humidity, and 8 hours light per day in a growing chamber (approx. 3x5 m, York International). The plants were watered as necessary until the soil became evenly moist. On the day before treatment with benzo- l,2,3-thiadiazole-7-thiocarboxylic acid-S- methyl ester, the plants were watered for the last time and excess water was removed immediately before treatment.

After 3 weeks of growing, the plants in 3 pots containing approx. 300 plants each were evenly sprayed with ca. 1 ml of an aqueous solution of Bion® (Syngenta) containing 100 μM of benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester. Another pot of plants received control treatment with ca. 1 ml of an aqueous solution of Bion® containing all components in the same concentration as used for the treatment, except for benzo-l,2,3-thiadiazole-7- thiocarboxylic acid-S-methyl ester. The solution was made by dissolving the active ingredient and formulation without active ingredient, respectively, in mains water using a laboratory mixer. Thereafter, the plants were kept for 3 days in the growing chamber. Three days after the spray treatment the plants were exposed to a frost stress of -14°C for 3.5 hours. Thereafter, the plants again were kept in the growing chamber under the aforementioned conditions. Seven days after the frost stress the appearance of the plants was evaluated.

It was found that almost all control plants treated with the formulation without active ingredient died because of the frost stress. In contrast, a large part of the plants namely about 30-50% treated with the solution of Bion® containing benzo- l,2,3-thiadiazole-7- thiocarboxylic acid-S-methyl ester recovered und showed afterwards visually unscathed growth.

Example 2

Determination of tolerance against frost of thale cress after application of benzo- 1,2,3- thiadiazole-7-thiocarboxylic acid-S-methyl ester

The treatment of thale cress with an aqueous solution of Bion® (Syngenta) was performed under the conditions as described in example 1 , wherein different therefrom, by two pots were treated with concentrations of 25 μM, 50 μM or 100 μM of benzo- 1,2,3-thiadiazo le-7- thiocarboxylic acid-S-methyl ester. Damage was evaluated seven days after the frost stress.

It could be seen that already when using a treatment with 25 μM benzo-l,2,3-thiadiazole-7- thiocarboxylic acid-S-methyl ester 30% to 50% of the plants survived the frost stress visually unscathed.

Also a large part of the plants namely about 30-50% treated with 50 μM or 100 μM of benzo- l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester recovered und showed afterwards visually unscathed growth.

In contrast, nearly all control plants in the control flower pots died because of the frost stress.

These examples show that a treatment of thale cress with benzo-l,2,3-thiadiazole-7- thiocarboxylic acid-S-methyl ester can protect the plants against frost stress.

Example 3

Determination of the gene expression of alternative oxidase Ia in thale cress after application of benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester

About 300 seeds (accession Columbia-0) each of thale cress (Arabidopsis thaliana) were distributed on potting soil (392 cm ³ , potting soil of Balster, Frόndenberg, Germany) in flower pots (7x7x 8cm, Gόttinger). Germination of the seeds was initiated by a stratification of 2 days at 4°C in the dark. Following, the plants were grown at 20 ⁰ C, 65 % relative humidity, and 8 hours light per day in a growing chamber (approx. 3x5 m, York International). The plants were watered as necessary until the soil became evenly moist. On the day before treatment with benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester, the plants were watered for the last time and excess water was removed immediately before treatment.

After 3 weeks of growing, 3 pots containing approx. 300 plants each were evenly sprayed with ca. 1 ml per pot of an aqueous solution of Bion® (Syngenta) containing 100 μM of benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester. Another three pots of plants received a control treatment with ca. 1 ml per pot of an aqueous solution of Bion® containing all components in the same concentration as used for the treatment, except for benzo- 1,2,3- thiadiazole-7-thiocarboxylic acid-S-methyl ester. Thereafter, the plants were kept for 3 days in the growing chamber.

Approx. 200 mg of the aboveground parts of the control plants and of the plants treated with 100 μM of benzo- l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester were removed for the determination of the gene expression of alternative oxidase Ia at 24, 48 and 72 hours after treatment.

The plant tissue was initially frozen in liquid nitrogen and stored at -80 ⁰ C in a freezer (Model C660 Premium, New Brunswick Scientific, Edison, NJ, USA) until further processing of the collected tissues.

At first, total RNA was isolated by means of TRI Reagent (Molecular Research Center, Cincinnati, OH, USA) according to manufacturers instructions, lμg of the isolated total RNA was incubated with 1 Unit DNasel/lOμl at 37° C for 30 minutes to inhibit contamination of the preparation with DNA. The DNase was inactivated afterwards by heating to 70° C for 15 minutes. Subsequently, the RNA was circumscribed into cDNA. For that purpose, 2,5 μM DNA random nonamers (Invitrogen), 1 mM Deoxy-NTPs (Fermentas GmbH, St. Leon Rot), M-MuLV-Buffer (Fermentas) and 200 Units of Revert Aid M-MuLV Reverse Transcriptase (Fermentas) were added per 20 μl reaction mixture and incubated at 37° C for 1 hour. The reaction was stopped by heating to 70° C for 10 minutes.

The amplification of gene specific DNAs was performed using Real-time RT-qPCR, an ABI PRISM 7000 Sequence detector (Applied Biosystems, Foster City, CA, USA), SYBR Green Master Mix (Applied Biosystems, Foster City, CA, USA) and gene specific oligonucleotide primers (Invitrogen) for the alternative oxidase (AOX) Ia gene. The final concentration of the gene specific primers was 0.2 μM each. 2 μl of the diluted cDNA were used as template. The conditions of the PCR reactions were as follows: An initial activation step for the polymerase was performed at 95°C for 10 minutes. Following, 40 amplification cycles at 95°C for 15 seconds each and an incubation at 60 ⁰ C for 1 minute were performed. The Real-time DNA amplification was recorded and analysed by the software ABI PRISM 7000 SDS 1.0 Software (Applied Biosystems, Foster City, CA, USA). The expression of the gene coding for Actin2 was used as in internal standard for adjusting to minor differences in the amount of the DNA templates.

Before treatment with 100 μM of benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester, control plants showed ca. 5% expression of the gene coding for the alternative oxidase Ia (AOXIa), relating to a relative graduation of 0 % to 100%. The expression of AOXIa in the control plants increased only marginally to about 8%, 10%, and 8 % on the first, second, and third day, respectively, after treatment with benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S- methyl ester.

In contrast, in plants exposed to 100 μM benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S- methyl ester, the expression of the gene alternative oxidase Ia (AOXIa) increased to beyond 20% on the first day after treatment, to beyond 60% on the second day after treatment, and amounted still to beyond 30% on the third day after benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester treatment, relating to a relative graduation of 0 % to 100%.

This shows that benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester induces the expression of the gene coding for alternative oxidase Ia (AOXIa) in thale cress. It is assumed

that the gene product is involved in an increased production of heat and the frost tolerance in thale cress induced by benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester.

Example 4

Determination of tolerance against drought of thale cress after application of benzo- 1,2,3- thiadiazole-7-thiocarboxylic acid-S-methyl ester

About 300 seeds (accession Columbia-0) of thale cress (scientific name: Arabidopsis thaliana) were distributed on potting soil (392 cm ³ , potting soil of Balster, Frόndenberg, Germany) in flower pots (7x7x8cm, Gόttinger). Germination of the seeds was initiated by stratification for 2 days at 4°C in the dark. Following, the plants were grown at 20 ⁰ C, 65 % relative humidity, and 8 hours light per day in a growing chamber (approx. 3x5 m, York International). The plants were watered as necessary until the soil became evenly moist. On the day before treatment with benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester, the plants were watered for the last time and excess water was removed immediately before treatment.

Experiments were performed both with 3-week- old and mature thale cress plants , which were grown 6 weeks under the aforementioned conditions. Plants of mature thale cress were individualised 3 weeks after bulk planting and, then, single plants were grown for another 3 weeks under the aforementioned conditions.

After being grown for three or six weeks, respectively, the plants in 2 pots each were evenly sprayed with 1 ml of an aqueous solution of Bion® (Syngenta) containing 100 μM of benzo- l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester. Another pot of plants received control treatment with 1 ml of an aqueous solution of Bion® containing all components in the same concentration as used for the treatment, except for benzo-l,2,3-thiadiazole-7-thiocarboxylic

acid- S -methyl ester. The solution was made by dissolving the active ingredient and formulation without active ingredient, respectively, in mains water using a laboratory mixer.

Thereafter, the plants were kept for 18 days in the growing chamber at 20 ⁰ C, and 8 hours light per day with 65 % relative humidity. During this 18-day-period the plants were not watered at all. After 18 days the appearance of the plants was evaluated.

It was found that essentially all control plants treated with the formulation without active ingredient died because of the drought. In contrast, the plants treated with the solution of Bion® containing benzo-l,2,3-thiadiazole-7-thiocarboxylic acid-S-methyl ester showed a visually unscathed growth despite of the period of 18 days of drought.

This example shows that a treatment of thale cress with benzo-l,2,3-thiadiazole-7- thiocarboxylic acid-S-methyl ester can protect plants against drought.