CA1284895C - Use of a (-)-antipode of 2-(4-chlorophenoxy-methyl)-3,3- dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-ol for regulating plant growth - Google Patents

Abstract

Agents for regulating plant growth ABTRACT

The (-)-antipode of 2-(4-chlorophenoxymethyl)-3,3 dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-ol of the formula (I)

Description

~34;~39~

The present invention relates to the use of the (-)-ant;podes ) of 2-t4-chlorophenoxymethyl)-3,3-dimethyl-1-t1,2,4-triazol-1-yl)-butan-2-ol for regulat;ng plant growth.
It is already known that the racemate of 2-(4-chlorophenoxymethyl)-3,3-dimethyl-1-t1,2,4-triazol-1-yl)-butan-2-ol has plant growth-regulating properties (compare EP-OS (European Published Specification) 0,040,345). The activity of this product is good; however, the effect achieved when very low amounts are applied is not always satisfactory.
It has now been found that the (-)-antipode of 2-(4-chlorophenoxymethyl)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-ol of the formula OH
Cl ~ O-CH2-*C-c~c~3)3 15 CH2 tl) 1 ~
~N`N

is distinguished by very good plant:growth-regulating properties.
Surprisingly, the (-)-antipode of 2-(4-chloro-phenoxymethyl)-3,3-dimethyl 1-t1,2,4-triazol-1-yl)-butan-2-ol o~ the formula (I) has considerably better plant growth-regulating properties than the corresponding race-mate, which is known from the prior art as a highly active .
*) The (-)-ant;pode is to be understood here in each case as that enantiomer which rotates the plane of oscilla-tion of linearly polarized llght of the sodium D line to th~ left Le A 24 157 -- :

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3L2~4~95 plant growth regulaeor. Moreover, it ~as not to be expected that the active compound wh;ch can be used according to the invention is distinguished by a very good plant gro~th-regulating activ;ty, wh;lst the (~)-antipode of 2-(4-chlorophenoxymethyl)-3,3-dimethyl-1-(1,2,4-tria-zol-1-yl)-butan-2-ol is largely inactive as a plant gro~th regulator~
Formula (I) provides a definition of the active compound which can be used according to the invention.
In this formula, the symmetrically substituted carbon atom is identified by (*).
The (-)-antipode of 2-(4-chlorophenoxymethyl)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-ol is not yet known. It can be prepared by a procedure in ~hich, in a 1st stage, racemic 2-(4-chlorophenoxymethyl)-2-tert.-butyl-oxirane of the for~ula Cl ~ -CH2 ~ ~CH3)~ (II) -~CH2 is reacted ~ith a strong, optically active acid, such as, for example, (~-camphor-10-sulphonic acid, in the pre-sence of a diLuent, such as, for exampler aceton;trile~
at temperatures between 10 and 60C, the diastereomeric ester mixture thus o~tained is then resolved on the basis of the different physical properties of the components contained therein and, thereafter, in a 2nd stage, the -individual diastereomers are reacted ~ith 1,2,4-triazole in the presence of a diluent, such as, for example, aceto-nitrile, and if appropriate in the presence of a base, such as, for example, potassium carbonate, at temperatures bet~een 40 and 120C.
If (~)-camphor-10-sulphonic acid is used as an optically active acid, the course of the preparation pro-cess described above can be illustrated by the following equation:
Le A 24 157 .. :

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~Z~39~

~1~30 - CH3 ;~ - C t CH3 ) 3 O--CH2 (~ )-An~ipoda ' 1 . ' ,.
OH
Cl ~ -CH2-l-CtCH3)3 Diastereomer.mixture o-soz-~:H2~3 r,h-romato~raph;c separat;on (+)-~amphcrr-10-sulphonic ~ (+)-Camphor-1~-sulphon;c ac;d ester of the (-)- acid ester of the (+)-ant;pode ant;pode ~ ~ .
HN l -t+)-Camphor- HN l ~ (+~-~amp~or-10-~N 10--s~ hon;c ~-=W suLphon; G' acid K2CO3 ac-id K2CO3 O~ OH
Cl ~ -CH2-~ CH3)3 tl ~ -~2-l*_C~cH3~3 fH2 . l H2 ~N

t - ) -An-ip~de t 4 ) -An~ipod~

:

Le A 24 157 . ~: ' ' ~

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The racemic 2-(4-chlorophenoxymethyl)-2-tert.-butyl-ox;rane of the formula (II) required as the starting substance in the abovementioned process is known tcompare EP-OS (European Published Specification~ 0,040,345).
As can be seen from the equaeion sho~n above, not only the (-)-antipode but also the (+)-an~ipode of 2-(4-chlorophenoxymethyl)-3,3-d;methyl-1-(1,2,4-triazol-1-yl)-butan-2-ol can be prepared by the process described.
The active compound according to the ;nvention engages in the metabolism of the plants and can therefore be employed as a growth regulator.
Experience to date of the mode of action of plant growth regulators has shown that an active compound can also exert several different actions on plants. The actions of the compounds depend essentially on the point in time at wh;ch they are used, relative to the stage of development of the plant, and on the amounts of active compound applied to the plants or their environment and the way in which the compounds are applied. In every case, growth regulators are intended to influence the crop plants in the particular manner desired.
PLant growth-regulating compounds can be employed, for example, to inhibit vegetative growth of~the plants.
Such inhibition of growth is, inter alia, of economic inter-est in the case of grasses, since it is thereby possibleto reduce the frequency of cutting the grass in ornamental gardens, parks and sportsgrounds, at verges, at airports or in fru;t orchards. The inhibition of gro~th of herba-ceous and woody plants at verges and in the vicinity of pipelines or overland lines or, quite generally, in areas in which heavy additional growth of plants is undesired, is also of importance~
The use of gro~th regulators to inhibit the growth in length of cereals is also important. The danger of bending ("lodging") of the plants before harvesting is thereby reduced or completely eliminated. Furthermore, Le A 24 157 . . .
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4~35 growth regulators can strengthen the stem of cereals, ~hich again counteracts lodging. Use of growth regula-tors for shortening and strengthening the stem enables higher amounts of fertilizer to be applied to increase the yield, without danger of the cereal lodging.
In the case of many crop plants, inhibition of the vegetative growth makes denser plant;ng possible, so that greater yields per area of ground can be achieved. An advantage of the smaller plants thus produced is also that the crop can be worked and harvested more easily.
Inhibition of the vegetative growth of plants can also lead to increases i-n yield, since the nutr;ents and assimilates benefit blossoming and fruit formation to a greater extent than they benefit the vegetative parts of plants.
Promotion of vegetative growth can also fre-quently be achieved with growth regulators~ This is of great utility if it is the vegetative parts of the plants ~hich are harvested. Promoting the vegetative gro~th can, however, also simultaneously lead to a promotion of generative growth, since more assimilates are formed, so that more fruit, or larger fruit~ is obtained.
Increases in yield can in some cases be achieved by affecting the plant metabolism, without noticeable changes in vegetative growth. A change in the compos;t;on of plants, which in turn can lead to a better quality of the harvested products, can furthermore be achieved with growth regulators. Thus it is possible, for example, to increase the content of sugar in sugar beet~ sugar cane~
pineapples and citrus fruit or to increase the protein content in soya or cereals. Using growth regulators it is also possible, for example~ to inhibit the degradation of desired constituents, such as, for example, sugar in sugar beet or sugar cane, before or after harvesting. It is al-so possible favourably to influence the production or theefflux of secondary plant constituents. The stimulation Le A 24_157 of latex flux in rubber trees may be ment;oned as an example.
Parthenocarpous fruit can be formed under the influence of growth regulators. Furthermore, the gender of the flowers can be ;nfluenced. Sterility of the pollen can also be produced, which is of great importance in the breeding and preparation of hybrid seed.
Branching of plants can be controlled by using growth regulators. On the one hand, by breaking the apical dominance the development of side shoots can be promoted, which can be very desirable, especially in the cultivation of ornamental plants, also ;n connection w;th growth inh;b;t;on. On the other hand, however, ;t ;s also poss;ble to ;nh;b;t the growth of s;de shoots. There is great interest in this action, for example, ;n the cul-t;vat;on of tobacco or ;n the plant;ng of tomatoes.
The amount of leaf on plants can be controLLed, under the ;nfluence of growth regulators, so that defolia-tion of the plants at a desired po;nt ;n t;me ;s achievsd.
Such defoliation is of great importance ;n the mechan;cal harvesting of cotton, but is also of interest for facili-tat;ng harvesting in other crops, such as, for example, ;n v;ticulture. Defol;at;on of the plants can also be carried out to lower the transp;rat;on of plants before they are transplanted.
~ he shedding of fruit can also be controlled with growth regulators. On the one hand, ;t is poss;ble to prevent premature shedding of fruit. However, on the other hand, shedding of fruit, or even the fall of blossom, can be promoted up to a certain degree ("thinning out") in order to interrupt the alternance. ~y alternance there is understood the pecul;ar;ty of some varieties of fru;t to produce very d;fferent y;elds from year to year, for endo-genic reasons. F;nally, us;ng growth regulators ;~ ;s poss;ble to reduce the force requ;red to detach the fru;t at harvest t;me so as to perm;t mechanical harvesting or Le A 24 1_ ,-34~35 facil;tate manual harvesting.
Using growth regulators, it is furthermore pos-sible to achieve an acceleration or retardation of ripen-ing of the harvest product, before or after harvest;ng.
This is of particular advantage, since it is thereby pos-sible to achieve optimum adaptation to market requirements.
Furthermore, gro~th regulators can at times improve the coloration of fruit. In addition, concentrating the ripening within a certain period o~ time is also achiev-able with the aid of growth regulators. This provides thepreconditions for being able to carry out complete mechani-cal or manual harvesting in only a s;ngle pass, for example in the case of tobacco~ tsmatoes or coffee.
Using growth regulators, it ;s furthermore pos-s;ble to influence the latent period of seeds or buds ofplants, so that the plants, such as, for example, pine-apple or ornamental plants in nurser;es, germinate, shoot or blossom at a time at ~hich they normally sho~ no readi-ness to do so. Retarding the shooting of buds or the germination of seeds with the aid of gro~th regulators can be desirable in regions where frost is a hazard, in order to avoid damage by late frosts.
Finally, the resistance of plants to frost, drought or 3 high salt content in the soil can be induced with growth regulators. Cultivation o~ plants in regions which are usually unsuitable for this purpose thereby becomes possible.
The active compound which can be used according to the invention can be converted to the customary formu-lations, such as solutions, emulsions, suspensions, po~-ders, foams, pastes, granules, aerosols, very fine cap-sules in polymeric substances and in coating compositions for seed, as well as ULV formulations.
These formulations are produced in kno~n manner, for example by mixing the act;ve compounds w;th extenders, that is, liqu;d solvents, liquefied gases under pressure, Le A 24 157 12~ '3~

andtor solid carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispers-ing agents, and/or foam-forming agents~ In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents. As liquid solvents, there are suitable in the main: aromatics, such as xylene, toluene or alkyl naphthalenes, chlorinated aromatics or chlorinated aLiphatic hydrocarbons, such as chlorobenzenes, chLoroethyLenes or methyLene chLoride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as ~ell as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl iso-butyl ketone or cyclohexanone, strongly polar solYents, such as dimethylformamide and dimethylsulphox;de, as well as uater. By liquefied gaseous extenders or carriers are meant liquids which are gaseous at normal temperature and under normal pressure, for example aerosol propellants, such as halog~nated hydrocarbons as well as butane, pro-pane, nitrogen and carbon diox;de. As sol;d carr;ersthere are suitable: for example, ground natural minerals, such as kaolins, clays, talc, chalk, ~uartz, attapulgite, montmorillonite or diatomaceous earth, and ground syn-thet;c m;nerals, such as highly-dispersed s;l;cic ac;d, alum;na and s;l;cates. As solid carriers for granules there are su;table: for example, crushed and frac~ionated natural rocks such as calcite, marble, pumice, sepiolite and dolomite, as well as synthetic granules of inorganic and organic meals, and granules of organic material such 3û as sawdust, coconut shells, maize cobs and tobacco stalks.
As emulsifying and/or foam-forming agents there are suit-able: for example, non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethyl-ene-fatty alcohol ethers, for example alkylaryl polyglycol ethers, alkylsulphonates, alkylsulphates, arylsulphonates as ~ell as albumin hydrolysation products. As dispersing Le A 24 157 agents there are suitable: for example, lign;n-sulph;te waste ~iquors and methyLceLluLose.
Adhesives such as carboxymethylcellulose and natural and synthetic polymers in the form of powders, granuLes or Latices, such as gum arabic, poLyv;nyl alcohol and poLyvinyL acetate, as weLL as natural phosphoLipids, such as cephalins and Lecithins, and synthetic phospho-l;p ds, can be used in the formulations. Further addi-tives can be mineral and vegetable oils.
It is possible to use colorants such as inorganic p;gments, for example iron oxide, titanium oxide and Prussian 8Lue, and organic dyestuffs, such as aLizarin dyestuffs, azo dyestuffs and metal phthalocyanine dye-stuffs, and trace nutrients such as salts of iron, mangan-ese, boron, c~pper, cobalt, molybdenum and zinc.
The formulations in general contain bet~een 0.1 and 95 per cent by weight of active compound, preferably between ~.5 and 90~.
The active compound uhich can be used according 2û to the invention can be present in the formulations as a mixture with other known active compounds, such as fungi-cides, ;nsect;c;des, acar;c;des and herbicides, and also as mixtures with ~ertili~ers and other growth regulators.
The active compound can be used as such, in the form of its formulations or as the use forms prepared therefrom, such as ready-to-use solutions, emulsifiable concentrates, emulsions, foams, suspensions, ~ettable powders, pastes, soluble powders, dusting agents and gran-ules. They are used in the customary manner, for example by ~atering, spraying, atomizing, scatter;ng, dusting, foaming, coating and the like. Furthermore, it is pos-sible to apply the active compound in accordance uith the ultra-low volume process or to inject the active compound preparation or the act;ve compound ;tself into the soil.
It is also possible to treat the seeds of plants.
The amounts applied can be varied with;n a sub-Le A 24 157 -,, ~L2~4~35 stantial range. In general, 0.01 to 50 kg, preferably 0.05 to 10 kg, of active compound are used per hectare of soil surface.
As regards the time of application, the rule is that the growth regulator is applied within a preferred per;od of time, the exact definition of which depends on the climatic and vegetative circumstances.
The preparation and use of the act;ve compound which can be used accord;ng to the invention are illustra-ted in the foLlouing examples.
Preparation Examples Example 1 C 1~3_ CH2-~C-C ( CH3 ) 3 ~2 ~¢~N ~ n~ ipode 1st stage OH
CI ~ -CH2-l_C(C~3)3 O-S02-CH2 ~

12.5 9 (0.05 mole~ of (+)-camphor-10-sulphonic acid are added to 12 g (0.û5 mol~) of racemic 2-(4-chloro-phenoxymethyl)-2-tert.-butyl-oxirane in 150 ml of aceto-nitrile at 20C, while ~tirring. The mixture is left to stand at room temperature for 16 hours, poured into ~ater and extracted with methylene chloride. The organ;c phase is washed t~ice ~ith ~ater, dried over magnesium Le A 24 157 ~ 284~39~

sulphate and concentrated in vacuo. 18 g of the diastereo-mer mixture of 2-(4-chlorophenoxymethyl)-3,3-dimethyl-2-hydroxy-1-butyl t~)-camphor-10-sulphonate are obtained as a viscous oil, from Nhich a pure diastereomer ~melting point: 103C) partly crystallizes out The diastereomer mixture is resolved by means of HPLC on silica gel in the system hexane/isopropyl ether.
This gives a) 5.2 g of fraction 1 as a colourless oil with an optical rotat;on of C320 = +21~6 (CHCl3, C = 0.67) and b) 5.0 g of fraction 2 of melting point 103C with an optical rotation of ~]2g = +32.8 (CHCl3, C = 1 02~.
Znd stage 0~
C 1~0- CH2- *C - C ~ CH3 ) 3 I
lH2 ~ N (-)^Antipode 5.2 g (11 mmol) of 2-(4-chlorophenoxymethyl)-3,3-dimethyl-2-hydroxy-1-butyl ~)-camphor-10-sulphonate according to fraction 1 of the first stage are heated under reflux with 3 9 ~43 mmol) of 1,2,4-triazole and 3 g (21 mmol) of potassium carbonate in 60 ml of acetonitrile The reaction mix~ure is then poured onto water and extrac-ted with methylene chloride and the organic phase is con-centrated. The crude product is purified by means of column chromatography in the system chloroform/ethyl acetate ~3:1). 2.2 g (68% of theory) of the (-)-antipode of 2-(4-chlorophenoxymethyl~-3,3-dimethyl-1-~1,2,4-triazol-1-yl)-butan-2-ol of melting point 57C and with an optical rotation of ~]2~ = -111.4~ (CHCl3) are obtained.

Le A _ 15_ ~8~

Example 2 OH
C~2 - *C - C ~ CH3 9 3 An~ i pod~

1st stage In this context, compare Example 1, 1st stage, fraction 2.
2nd stage Cl{~)-CH2-*C-C(CH3)3 ~ N (~)-An~;pode 8.0 9 ~17 mmol~ of 2-~4-chlorophenoxymethyl)-3,3-dimethyL-2-hydroxy-1-butyl (f)-camphsr-1a-sulphonate according to fraction 2 of the 1st stage of Example 1 are heated under reflux ~ith 5 g (72 mmol) of 1,2,4-triazole and 5 9 (35 mmoL) of potassium carbonate ;n 80 ml of acetonitrile for 8 hours, while stirr;ng. The reaction mixture is then poured onto water and extracted ~ith methylene chloride and the organic Phase is concentrated.
The oily residue is dissolved in cyclohexane. The sym-metric tr;azole derivative thereby crystallizes out (1.2 9 of melting point 220C), and is filtered offO
The f;ltrate is concentrated in vacuo and the oily residue is brought to crystall;zation uith petroleum eeher.

3.2 9 ~57% of theory) of the (~)-antipode of 2-~4-chloro-phenoxymethyl)-3,3-dimethyl~ 1,2,4-triazol-1-yl)-butan-Le A 24 157 -:.' , . :
: ~ , . ' -' 3~ 5 2-ol of melting point 57C ~ith an optical rotation of C~]20 = ~113 (CHCl3) are obtained~
The compounds shown below are tested in respect of their plant growth-regulating properties in the follow-ing use examples:

= OH
C1 ~ O-cH2~ c~cH3)3 I
lH2 N SRac~ma~e) ~B) c ~ :
Gl ~ -~2~~C~c(~3)3 C~2 I

f1N~N ~ An~ipode Il 11 N--OH
Cl{~O-CH~-*C-i:(CH3)3 ~2 1- ) -Ant ipode _ (accordin~ to the invention) Le A 24 157 .

9~

Example A
Growth of grass (Festuca pratens;s~
-Solv2nt: 30 parts by ~eight of dimethyLformamide Emulsifier: 1 part by weight of polyoxyethylene S sorbitan monolaurate To produce a suitable preparation of active com-pound, 1 part by weight of active compound ;s mixed w;th the stated amounts of solvent and emulsifier and the mix-ture ;s made up to the desired concentration with water.
Grass tFestuca pratensis) is gro~n in a greenhouse up to a he;ght ;n gro~th of 5 cm. In th;s stage, the plants are sprayed ~ith the preparat;ons of active com-pound until dripping uet. After 2 weeks, the add;t;onal grouth ;s measured on alL the plants and is calculated in per cent of the additional growth of the control plant`s.
100X denotes an additional gro~th corresponding to that of the controls, values below 100% ;ndicate growth inhi-bition and values above 100% indicate promotion of growth.
The act;ve compounds, act;ve compound concentrat;ons and results of the experiments can be seen from the follow-ing table.

Le A 24 157 ~IL2~ 5 Table A
Gro~th of grass (Festuca pratens;s) Act;ve compoundConcentrat;on ;n % ~dditional growth in %
_ _ ~ - = 100 (Control) (I) 0.05 ~4 ) (accord;ng to the invent;on) (~) 0.05 1û8 .
) dark green leaf colour Le A 24_157 ~L~2~34~395 Example B
Gro~th of barley Solvent: 30 parts by weight of dimethylformamide Emulsifier: 1 part by weight of polyoxyethylene sorbitan monolaurate To produce a suitable preparation of active com-pound, 1 part by weight of active compound is mixed with the stated amounts of solvent and emulsifier and the mix-ture is made up to the desired concentration with water.
Barley plants are grown in a greenhouse to the 2-leaf stage. In this stage, the plants are sprayed with the preparations of active compound untiL dripping ~et.
After 2 weeks, the additionaL gro~th is measured and caL-culated in per cent of the additional growth of the con-troL pLants. 100X denotes an additionaL growth corre-sponding to that of the controls, values below 10û% indi-cate growth inhibition and values above 100% indicate promotion of grouth.
The active compounds, active compound concentrat;ons and results of the experimen~s can be seen from the follow-ing table:

Le A 24 157 :
` ' :' '` ~ - , ~2~ 395 Table B
Growth of barley Add;tional growth Active compound Concentration ;n % ;:n (Control) tI) 0.05 28 (according to~~ 0.025 29 the ;nvent;on) 0.01254~
0~006253 t~) 0,05 ~7 o ~ nzs99 - ~.0125~2 a.oo6299 tA) 0.05 60 0.025 4~
0~012~70 0.0062a1 *) dark green leaf colour Le A 24 157 ,, ' : "~

~2~8g5 Example C
Growth of sugar beet .
Solvent: 30 parts by weight of dimethylformam1de Emulsifier: 1 part by weight of polyoxyethyLene sorbitan monolaurate To produce a suitable preparation of active com~
pound, 1 part by ~eight of active compound is mixed with the stated amounts of solvent and emulsifier and the mixture is made up to the desired concentration with water.
Sugar beet is grown in a greenhouse until for-mation of the cotyledons is compLete. In this stage, the plants are sprayed with the preparation of active com-pound until dripping wet. After 14 days~ the additional growth is measured and calculated in per cent of the additional growth of the control plants. 100X dentoes an additional growth corresponding to that of the controls, values below 100% indicate growth inhibition and values above 100% indicate promotion of growth.
The active compounds, active compound concentrations and results of the experiments can be seen from the follow-ing table.

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- 1q -Table C
Gro~th of sugar beet Addit;onal gro~th Act;ve compound Concentration ;n % in Z

- - ' 10~
(Control) ~I) 0~05 S *) (accordins to 0.025 g *) the invent;on)0.0125 18 *) 0~0062 28 *) O~i ~12 * ~
~ ,. 025 65 * ) 00~125 7~4 *) D ~ 0062 7~ ~ ) (A) 0,05 ~ *) 025 1 8 * ) 0.0125 2:~ *) *) dark green leaf colour, thick leaves **) leaf deformations Le A 2~ 157 ' - ..
'~' ' -~34~3~35 ExampLe D
Growth of soya beans Solvent: 30 parts by weight of d;methylformamide Emulsifier: 1 part by ~e;ght of polyoxyethylene sorbitan S monolaurate To produce a suitable preparation of active com-pound, 1 part by weight of active compound is mixed ~ith the stated amounts of solvent and emulsifier and the mix-ture is made up to the desired concentration with ~ater.
Soya bean plants are grown in a greenhouse until the 1st secondary leaf has unfolded completely. In this stageO the plants are sprayed with the preparations of active compound until dr;pping wet. After 2 weeks, the additionaL growth is measured and calculated in per cent of the additional growth of the control plants. 100%
denotes an additional growth corresponding to that of the - controls, values below 100~ indicate gro~th inhibition and values above 100% indicate promotion of gro~th.
The active compounds, active compound concentrat;ons and results of the experiments can be seen from the follow-ing table.

Le A 24 157 .
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Table D
Gro~th of soya beans Active compound Concentrat;on in % Additiorxal growth -- - = 100 (Control) 59 * ) (according to o,oz~ ~o ~) the ;nvent;on) 0~0125 14 *~
0,0062 17 *) ~B) 0.05 66 0.02~ 99 0.0125 ~7 0~0062 94 (A) 0.05 12 *) 0~025 14 *) O.~lZ5 ~1 *) 0.~62 26 *) dark green leaf colour Le A 24 157 ' ~ ' ' ~ ~ ' - ' '~ ' ' . '

Claims (6)

1. A method of regulating the growth of plants which comprises applying to such plants or to a locus in which plants are growing or to be grown, a plant-growth regulating effective amount of an (-)-antipode o? 2-(4-chlorophenoxymethyl)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-ol of the formula (I) (I) substantially free of the (+)-antipode.

2. A method according to claim 1 wherein the compound is applied in the form of a composition containing said compound as active ingredient in admixture with a suitable carrier or diluent.

3. A method according to claim 2 wherein the active ingredient concentration in said composition is between 0.1 and 95% by weight.

4. A method according to claim 2 wherein the active ingredient concentration in said composition is between 0.5 and 90% by weight.

5. A method according to claim 1, 2, 3 or 4 wherein the compound is applied to an area of cultivation at a rate of be-tween 0.01 and 50 kg/ha.

6. A method according to claim 1, 2, 3 or 4 wherein the compound is applied to an area of cultivation at a rate of be-tween 0.05 and 10 kg/ha.