CA1137773A - Method for inhibiting the growth of side shoots on tobacco plants - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The known O-(2-nitro-4-methylphenyl)-O-methyl-N-isopropyl-phosphoramidothioate of the formula

Description

The present invention relates to the use, as agents for regulating plant growth, of a certain amido-thiono-phosphoric acid ester, which is a known compound.
It is already known that similar amido-thiono-phosphoric acid esters have herbicidal properties (see German Auslegeschrift (German Published Specification) 2,001,771).
It is also known that a product which is commercially available under the trade name "Off-Shoot-T" and is based on fatty alcohols with 6, 8, 10 and 12 carbon atoms can be employed for regulating plant growth, in particular for suppressing the growth of side shoots of tobacco (see Farm. Chem. Handbook 1975, Meister Publishing Co., Willoughby, Ohio, 1~75 and Pesticide Dictionary D
147). However, the action of this product is not always satisfactory, l especially when low amounts are used.
,;`j It has now been found that the compound O-(2-nitro-4-methylphenyl)-O-methyl-N-isopropylphosphoramidothioate of the formula ~, ' NO~
~ 3 > S ~ CH3 (I) ! /HC-HN
, /

is particularly suitable for inhibiting the growth of side shoots (suckers) on tobacco plants.
Accordingly, the present invention provides a method for inhibiting the growth of side shoots on tobacco plants which comprises applying to the plants or their habitat an effective amount of 0-(2-nitro-4-methylphenyl)-O-methyl-N-isopropyl-phosphoramidothio-, .:

7 ~3 ate of the formul.a H C \~ I O ~ - CH3 (I) Surprisingly, the compound tI) which is used according to the invention exhibits a considerably more powerful side shoot-inhibiting activity on tobaeco plants than Off-Shoot-T, which is known from the state of the art and is an active compound of hiyh aetivity and the same type of aetion. The substance used according to the invention thus represents a valuable enrichment of the art.
The eompound (I) used according to the invention is known (see German Auslegeschrift (German Published Speeifieation)

2,001,771). However, its use for regulating plant growth, speeifi-eally for inhibiting the growth of side shoots on tobaceo plants, is new.
The compound I used aceording to the invention can be prepared by a process in which (a) an O-methyl-N-isopropyl-amido-thiono-phosphoric aeid ester halide of the general formula H3C ~ S
/ P-Hal (II) in whieh Hal represents ehlorine or bromine, is reaeted with a phenol derivative of the general formula N ~ CH3 (III)

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in wh.ich M represents hydrogen, an alkali metal or ammonium, if appropriate in the presence of an acid-binding agent, such as potassium carbonate or sodium carbonate, and iE appropriate in the presence of an inert organic solvent, for example acetonitrile, a-t temperatures between 30C and 110C, preferably between 40C and 70C, or in which (b) an 0-(2-nitro-4-methylphenyl)-N-isopropylami.dothiono-phosphoric acid ester halide of the general Eormula NO
Hal S ~CH3 ( IV) : i-H7C3-NH
in which Hal has the meaning stated above, '~l, is reacted with an alkali metal methoxide of the general formula I M'-O-CH (V) :il, in which M' represents sodium or potassium, :~
i in the presence of an inert organic solvent, for example a lower :l alcohol, at temperatures between 30C and 110C, preferably between :, 40C and 70C, or in which .. (c) an O-methyl~O-(2-nitro-4-methylphenyl)-thionophosphoric acid ester halide of the general formula NO~

\ P - o ~ = C~3 (VI1 in which Hal has the meaning stated above, , is reacted with isopropylamine in an inert organic solvent, such as acetonitrile, at temperatures between 30C and 110C, preferably between 40C and 70C.

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Experience -to date of the mode of action of plant growth regulators has shown that an active compound can exert one or ` several different actions on plants~ The actions of the compounds depend essentially on the point in time at which they are used, relative to the stage of development of the seed or 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 the present case, compound (I) has outstanding properties when used on tobacco plants, normally at the stage of removing the apical vegetative tips, in the inhibition of side~shoot or sucker growth.
This provides the preconditions for being able to carry out complete mechanical or manual harvesting o~ tobacco plants in only a single pass.
The active compound (I) can be converted into the cus-tomary formulations, such as solutions, emulsions, suspensions, ' powders, foams and ULV cold mist and warm mist formulations.
These formulations may be produced in known manner, for example by mixing the active compounds with extenders, that is to say liquid or solid carriers, optionally with the use of surface-active agents, that is to say emulsifying agents and/or dispersing 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 diluents or carriers, especially solvents, there are suitable in the main, aromatic hydrocarbons, such as xylene, toluene or alkyl naphthalenes, chlorinated

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aromatic or chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic or alicyclic hydrocarbons, such as cyclohexane ~` or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and ~, esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, or strongly polar solvents, such as dimethylformamide and dimethylsulphoxide, as well as water.
As solid carriers there may be used ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous ear~h, and ground synthetic minerals, such as highly-dispersed silicic acid, alumina and silicates. As solid carriers for granules ` 15 there may be used crushed and fractionated 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 as sawdust, coconut shells, maize cobs and tobacco stalks.
As emulsifying and/or foam-forming agents there may be used non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylaryl polyglycol ethers, alkyl sulphonates, alkyl sulphates, aryl sulphonates as well as albumin hydrolysis products. Dispersing agents include, for example, lignin sulphite waste liquors and methylcellulose.
Adhesives such as carboxymethylcellulose and natural and synthetic polymers in the form of powders, granules 30 or latices, such as gum arabic, polyvinyl alcohol and ;~
polyvinyl acetate, can be used in the formulations.
It is possible to use colorants such as inorganic pigments, for example iron oxide, titanium oxide and Prussian Blue, and organic dyestuffs, such as alizarin ~ 35 dyestuffs, azo dyestuffs or metal phthaloFyanine dyestuffs, ::

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77~;3 ~ and trace nutrients, such as salts oE iron, manganese, boron, ?,~ copper, cobalt, molybdenum and zinc.
The formulations in general contain from 0.1 to 95 per cent by weight of active compound, preferably from 0.5 to 90 per ; cent by weight.
The active compound according to the invention can be present in the formulations as a mixture with other active compounds, such as fungicides, insecticides, acaricides and herbicides, and - also as a mixture with fer-tilisers and other growth reyulators.
` 10 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, wettable powders, pastes, soluble powders, dusting agen-ts and granules. These may be used in the customary manner, for example by watering, spraying, atomising, scattering, dusting, ` foaming and gassing.
- The active compound concentrations can be varied within a substantial range. In general, 0.01 to 50 kg, preferably 0.05 to 10 kg, of the active compound are employed per hectare.
In the following Example, the activity of the compound (I) . , .
used according to the invention is illustrated.
,~ The known comparison compound is identified as follows:
Off-Shoot-T = a commercially available growth regulator based on ~ fatty alcohols with 6, 8, 10 and 12 carbon atoms.
;~ Inhibition of growth of side shoots of tobacco ; Solvent: 30 parts by weight of dimethylformamide Emulsifier: l part by weight of polyoxyethylene sorbitan monolaurate To produce a suitable preparation of active compound, , . . ~

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! 1 part by weight of active compound was mixed with the stated amounts of solvent and emulsifier and the mixture was made up to the desired concentration with water.
Tobacco plants were grown in a greenhouse until the 7th foliage leaf had unfolded. In this stage, the apical vegetative l tips of the plants were removed and the plants were sprayed with 'f the preparations of active compound until dripping wet. After 3 I weeks, the side shoots of the planls were broken ofE and weighed.
i The weight of the side shoots of the treated plants was compared with that of the control plants. 100% inhibition denoted the absence of side shoots and 0~ denoted a growth of side shoots which corresponded to that of the control plants.
The active compounds, active compound concentrations and results can be seen from the table which follows.
T A B L E C
Inhibition of growth of side shoots of tobacco Active Compound Active compound con- Inhibition of centration in ~growth in ~
3~ :
' 20 - - =
(control) Off-Shoot-T 0.2 20 Compound (I) 0.2 92 Compound (I) 0.4 99 Compound (I) 0.6 99 _eparative Examples Example 1 3 \ p _ O ~ CH3 (I) i-EI7C3N ~

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18.8 g (0.1 mol) of O-methyl-M-isopxopylamidothiono-phosphoric acid ester chloride were added dropwise to a mixture of 15.3 g (0.1 mol) of 2-nitro-4~methyl-phenol, 14.0 g of anhydrous potassium carbonate and 100 ml of acetonitrile at 50C to 60C, whilst stirring intens-~ ively.
- The mixture was stirred at 70C for a further 5 hours in order to bring the reaction to completion. The inorganic salt formed was filtered off and the filtrate was distilled to remove the solvent. The residue was taken up in 100 ml of benzene and the benzene solution was washed with 1% strength aqueous sodium carbonate solution and dried over anhydrous sodium sulphate. After distilling off the benzene and recrystallising the residue from a mixture of carbon tetrachloride/n-hexane, O-t2-nitro-4-methylpheny~-O-methyl-N-isopropylphosphoramidothioate was obtained. M.p. 54-56C.

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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Method for inhibiting the growth of side shoots on to-bacco plants which comprises applying to the plants or their habitat an effective amount of O-(2-nitro-4-methylphenyl)-O-methyl-N-iso-propyl-phosphoramidothioate of the formula (I)

2. Method as claimed in claim 1 wherein said compound is used in admixture with an agriculturally acceptable carrier.

3. Method as claimed in claim 1 wherein said compound is applied to an area of tobacco plant cultivation in an amount of 0.01 to 50 kg per hectare.

4. Method as claimed in claim 1 wherein said compound is applied to an area of tobacco plant cultivation in an amount of 0.05 to 10 kg per hectare.

5. Method as claimed in claim 1, 2 or 4 wherein said compound is applied directly to the vegetative parts of the tobacco plant.

6. Method as claimed in claim 1, 2 or 4 wherein said compound is applied directly to the vegetative parts of the tobacco plant in the form of an aqueous spray.