GB1572470A

GB1572470A - Method of protecting plants against damage by frost

Info

Publication number: GB1572470A
Application number: GB5181/77A
Authority: GB
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1976-02-09
Filing date: 1977-02-08
Publication date: 1980-07-30
Also published as: IL51404A; DE2705034A1; DK143882B; FR2340046A1; ATA81077A; JPS5298158A; FR2340046B1; DK52677A; BE851198A; DD129995A5; CH621043A5; CA1098331A; IL51404A0; NL7701320A; AT353551B; DK143882C; CS212786B2

Abstract

To protect plants against frost damage, the plants, or parts of plants, to be protected are treated before the incidence of frost or the beginning of winter with a composition which contains, as the ingredient which imparts frost resistance, a hydroxamic acid derivative of the formula <IMAGE> in which R1 is optionally substituted C3-C17-alkyl or C5-C7-cycloalkyl or optionally substituted phenyl and R2 and R3 in each case denote hydrogen, C1-C5-alkyl, alkylcarbonyl or arylcarbonyl, but in which R3 can also be the equivalent of a metal, ammonium or quaternary ammonio cation. The process and the composition are particularly suitable for protecting fruit plantations, vegetables and ornamentals, the preferably used hydroxamic acid derivatives being t-C4H9-CO-NHOH and CH3(CH2)4-CO-NHOH.

Description

(54) METHOD OF PROTECTING PLANTS AGAINST DAMAGE BY FROST (71) We, CIBA-GEIGY AG., a Swiss body corporate, of Basle, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention provides a method of protecting plants, in particular plant cultures, such as fruit, vegetables, ornamentals including shrubs and trees, and plant parts against damage by frost.

The prevention of frost damage to crops of cultivated plants is an extremely important problem in agriculture and horticulture. For this reason numerous active substances and measures have been proposed in order to increase the freeze resistance, that is to say the resistance of cultivated and ornamental plants to the action of cold and frost and in this way to prevent frost damage. Besides the application of polymers, foams and mists, the application in question Is often of substances which constitute protectives against the destruction of the plant cells by freezing caused by damage to the membranes. Frost damage is frequently attributable to irreversible structural changes in the cell membranes and consequently of associated proteins, that is to say for example to changes in the permeability which result in the collapse of vital cell functions, such as oxidative phosphorylation.

A large number of substances for protecting plant cells against destruction by freezing have been proposed, but all of them are not entirely satisfactory, because their application is restricted only to specific plants or because they induce phytotoxic side-effects.

It has also been proposed to use growth regulators which lower the metabolism of the plant and bring about a reduction of the vegetative growth and so maintain the plant in the dormant state, so that is becomes much less susceptible to frost.

The surprising discovery has now been made that hydroxamic acid derivatives of the formula I

or of the "tautomeric" formula Ia

wherein R, represents a substituted or unsubstituted alkyl group of 1 to 17 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, an alkenyl group of 2 or 3 carbon atoms, or a substituted or unsubstituted phenyl group, R2 represents a hydrogen atom or a substituted or unsubstituted alkyl group of I to 4 carbon atoms, and R3 represents a hydrogen atom, a methyl group, an alkylcarbonyl group of not more than 11 carbon atoms in the alkyl moiety, an unsubstituted or substituted phenylcarbonyl group, a methylcarbamoyl, an amine or ammonio cation or a metal cation of the formula 1/nMn+ (wherein M is a metal atom and n is its valency), are exceptionally suitable as frost protectives for cultivated plants, such as in particular fruit crops (citrus fruit, peaches, apples etc.), and also vegetables and ornamentals including shrubs and trees.

Suitable metal cations R3 are chiefly those of alkali metals and alkaline earth metals, and also those of trace elements, such as copper, iron and manganese.

According to the present invention there is provided a method of protecting plants or plant parts against frost damage which comprises applying to the plants or plant parts to be protected, just before the onset of or during winter but at least one day before a suspected outbreak of frost, a compound of the formula I or Ia.

Preferably the compound is applied in the form of a composition containing an effective amount of a compound of the formula I or Ia.

The active compounds of the formula I and Ia exert a substantially continuous protective action which, on application in the autumn, lasts into the spring. The protective action occurs immediately, so that treatment on the day before an outbreak of frost guarantees satisfactory protection against frost damage.

Preferably, those compounds of the formula I are used in which R, represents a phenyl group or an alkyl group of 3 to 8 carbon atoms, R2 represents a hydrogen atom or a methyl group, and R3 represents a hydrogen atom, one of the cations referred to, especially an alkali metal cation, or a methyl, alkylcarbonyl or phenylcarbonyl group.

The majority of the active compounds of the formula I and Ia are known compounds and are described, for example, in Houben-Weyl, Vol. 8, pp. 684--692; Beilstein, Vol. 9, page 341 and in other literature sources. They are compounds which are stable and soluble in water and ordinary organic solvents.

A number of hydroxamic acid derivatives of the above mentioned type have already been proposed as herbicides and fungicides and as growth stimulators in veterinary medicine (for example US patent specification 3,714,361). Some representatives of this active compound class can cause phytotoxic side-effects. In this event it is expedient to optimise the ratio of frost-protective action to phytotoxic effect by additional measures (choice of dose etc.).

Some hydroxamic acid derivatives also exhibit plant growth-regulating properties, such as growth inhibition and the promotion of fruit and leaf abscission.

Alkyl groups R1 and R2 can be straight-chain or branched. Preferred substituents of such alkyl groups are halogen atoms, such as chlorine, also phenyl (gives benzyl etc.) and alkoxy groups, such as methoxy. Phenyl groups R, and phenyl groups as moieties of phenylcarbonyl groups R3 can be substituted by halogen (such as chlorine), lower alkyl and alkoxy and by nitro groups.

Active compounds which exemplify hydroxamic acid derivatives of the formula

are listed in the following table:

Physical constants Compound R1 R2 R3 m.p. in OC. 1 CH3(CH2)4- H H 63-65 2 C6H5- H -COC6H5 59-61 3 cyclohexyl H H 1300 4 n-C817 H H 76-77 5 n-C11H23 H H 90-99 6 nC17H35 H H 900 7 tert. C4H9 H H 167-168 8 C6H5 H H 127-129

Compound l RZ R2 m.p. in OC. 9 CH3O-C6H4- H H 160-163C 10 n-C6H13 H H 67-69 11 CHA(CH2)4- H Ks amorphous 12 n-C3H7 H H 420 13 n-C4H9 H H 14 n-C7HIs H H 790 15 CH3(CH2)3-CH- H H CH3 16 tert.C4Hg H CH\ 17 CH-(CH,) 3 ; H H y CH3 18 cyclopentyl H H 19 CHO-(CH2)4- H H 20 Cl-(CH2)5- H H 21 m-chlorophenyl H H 22 o-tolyl H H 23 3-methyl-4- chloroph enyl H H 24 CHa(CH2)4 C2Hs H 25 CH(CH)4- CH3 CH3 26 CH3(CH2)4- H t[(CH2)2OH]3 27 CH3(CH2)4- H HNO+(C2H)3

Physical constants Compound Rl R2 R3 m.p. in OC 28 tert. C4Hg H KO > 2500 29 tert.C4H9 H -CO-CH, 114-1160 30 n-Cs H11 CH3 CH3 b.p. Ii = 960 31 tert.C4Hg CH3 - CH3 b.p.l2 = 620 32 n-CsHIl H -COCH2 76-790 33 tert.C4Hg H 3 Fe +++ > 2700 34 iso-C3H7 H H 1160 35 tert.C4Hg H CH3 n2D0= 1.4439 36 tert.C4Hg H -CONHCH2 900 37 n-C4H9 H -COCH3 62-650 38 Cl-(CH2)5- CH3 CH3 b.p.l3 = 1130 39 cyclopropyl H K+ 114-117? 40 cyclopropyl H H 1160 41 tert.C4H9 H -C0-tert.C4H3 147-1480 42 CH2(CH2)2-CH- H Cu++ > 200 C2H5 43 p-toluidyl H H 143-1440 44 2,4-dichlorophenyl H H 158-1j90 45 CH2--CH- H H 115-1160 46 benzyl H H 139-1400 47 CH2 H H 87-890 48 C2H5 H H 68-690 49 ClCH2- H H 85-900 50 tertC4H9 H -CO-C6H3 105-1060 51 tert.C4Hg H -CO-C11H23(n) 36-380 52 tert.C4Hg H -CO oC1 122-1240

Physical constants Compound R1 R2 R3 m.p. in OC 53 n-C4Hg H H 54 n-C ,H,-CH- H H CHa 55 iso-C4H9 H H 7275 56 n-C4H9-CH- H H C2Hs C2H5 C,H, y C2H5 58 CH3-CH=CH-- H H

Hydroxamic acid derivatives of the "tautomeric" formula

Physical Compound R1 Ra R2 constants 59 N-C5H11 CH3 CH3 b.p. 40 = 700C 60 phenyl H C2H, m.p. 60 - 650C 61 CH3 C2Hs m.p. -25 - 260C Suitable carriers and additives in the compositions of the present invention can be solid or liquid-and correspond to the substances customarily used in the art of formulation, for example natural or regenerated mineral substances, solvents, dispersants, wetting agents, thickeners, binders or fertilisers.

For application, the compounds of the formula I can be formulated as follows: Solid formulations: dusts, tracking agents, microgranules.

Liquid formulations: a) water-dispersible active substance concentrates: wettable powders, pastes, emulsions; b) solutions.

Solid formulations (dusts, tracking agents) are obtained by mixing the active substances with solid carriers. Suitable carriers are, for example: kaolin, talc, bolus, loess, chalk, limestone, ground limestone, attaclay, dolomite, diatomaceous earth, precipitated silica, alkaline earth silicates, sodium and potassium aluminium silicates (feldspar and mica), calcium and magnesium sulphates, magnesium oxide, ground synthetic materials, fertilisers, for example ammonium sulphate, ammonium phosphate, ammonium nitrate, urea, ground vegetable products, such as corn meal, bark dust, sawdust, nutshell meal, cellulose powder residues of plant extractions, activated charcoal etc. These substances can either be used singly or in admixture with one another.

Poiymer granules can also be prepared by impregnating a finished, porous polymer granulate (urea/formaldehyde, polyacrylonitrile, polyester and others), which has a specific surface area and a favoura'ole predetermined adsorption/desorption ratio, with the active substances, for example in the form of their solutions (in a low boiling solvent) and removing the solvent. Polymer granules of this kind in the form of microgranules having a bulk density of 300 g/litre to 600 g/litre can also be manufactured with the aid of atomisers. The dusting can be carried out from aircraft over extensive areas of cultures of useful plants.

It is also possible to obtain granules by compacting the carrier with the active substance and carriers and subsequently comminuting the product.

To these mixtures can also be added additives which stabilize the active substance and/or nonionics, anionics and cationics, which, for example, improve the adhesion of the active ingredients on plants or parts of plants (tackifiers and agglutinants) and/or ensure a better wettability (wetting agents) and dispersibility (dispersing agents).Examples of such substances are: olefin/chalk mixture, cellulose derivatives (methyl cellulose, carboxymethyl cellulose), hydroxyethyl glycol ethers of monoalkyl and dialkyl phenols having 5 to 15 ethylene oxide radicals per molecule and.8 to 9 carbon atoms in the alkyl moiety, lignin-sulphonic acids, the alkali metal and alkaline earth metal salts thereof, polyethylene glycol ethers (carbowaxes), fatty alcohol polyethylene glycol ethers having 5 to 20 ethylene oxide radicals per molecule and 8 to 18 carbon atoms in the fatty alcohol moiety, condensation products of urea and formaldehyde, and also latex products.

Water-dispersible concentrates, i.e. wettable powders, pastes and emulsifiable concentrates, are compositions which can be diluted with water to the desired concentration. They consist of active substance, carrier, optionally additives which stabilize the active substance, surface-active substances and anti-foam agents and, if appropriate, solvents.

Wettable powders and pastes are obtained by mixing and grinding the active substances with dispersing agents and pulverulent carriers in suitable devices until homogeneity is attained. Suitable carriers are, for example, those already mentioned for the solid formulations. In some cases it is advantageous to use mixtures of different carriers.As dispersing agents there can be used, for example, condensation products of sulphonated naphthalene and sulphonated naphthalene derivatives with formaldehyde, condensation products of naphthalene or naphthalene sulphonic acids with phenol and formaldehyde, as well as alkali metal, ammonium and alkaline earth metal salts of ligninsulphonic acid, in addition alkylarylsulphonates, alkali metal and alkaline earth metal salts of dibutylnaphthalene sulphonic acid, fatty alcohol sulphates, such as salts of sulphated hexadecanols, heptadecanols, octadecanols, and salts of sulphated fatty alcohol glycol ethers, the sodium salt of oleyl methyl tauride, ditertiary acetalene glycols, dialkyldilauryl-ammonium chloride and fatty acid alkali metal and alkaline earth metal salts.

Suitable anti-foam agents are for example silicones.

The active substance is so mixed, ground sieved and strained with the additives mentioned above that, in wettable powders, the solid particle size of 0.02 to 0.04 mm and in pastes, of 0.03 mm, is not exceeded. Emulsifiable concentrates and pastes are manufactured by using dispersing agents, such as those cited previously above, organic solvents, and water. Examples of suitable solvents are alcohols, aromatic hydrocarbons with a low freezing point (below -20"C), such as o-xylene, m-xylene, toluene, and mineral oil fractions which boil between 120 and 350"C.

The solvents must be practically odourless, not phytotoxic, and inert to the active substances.

Furthermore, the compositions according to the invention can be applied in the form of solutions. For this purpose the active substance or several active substances of the general formula I are dissolved in suitable organic solvents, mixtures of solvents or in water. Aliphatic and aromatic hydrocarbons, chlorinated derivatives thereof, alkylnaphthalenes and mineral oils, singly or in admixture, can be used as organic solvents.

The above described compositions contain between 0.1 and 95%, preferably between I and 80%, of active compound. Application formulations can be diluted to the desired concentration.

The active substances of the formula I can be formulated for example as follows: Dusts The following substances are used to obtain a) a 5% and b) a 2% dust: a) 5 parts of active substance, 95 parts of talc; b) 2 parts of active substance, I part of highly disperse silicic acid, 97 parts of talc.

The active substances are mixed with the carriers and ground.

Granules The following substances are used to produce 5% granules: 5 parts of active substance, 0.25 parts of epicblorohydrin, 0.25 parts of cetyl polyglycol ether, 3.50 parts of polyethylene glycol, 91 parts of kaolin (particle size 0.3--0.8 mm).

The active substance is mixed with epichlorohydrin and the mixture is dissolved in 6 parts of acetone. The polyethylene glycol and cetyl polyglycol ether are then added. The resultant solution is sprayed on kaolin, and the acetone is subsequently evaporated in vacuo.

Wettable powder: The following constituents are used for the preparation of a) a 70%, b) and c) a 25%, and d) a 10% wettable powder: a) 70 parts of active substance, 5 parts of sodium ligninsulphonate, 1 part of sodium dibutylnaphthalenesulphonate, 24 parts of silicic acid, b) 25 parts of active substance, 4.5 parts of calcium ligninsulphonate, 1.9 parts of Champagne chalk-hydroxyethyl cellulose mixtureAl:l), 1.5 parts of sodium dibutylnaphthalenesulphonate, 19.5 parts of silicic acid, 19.5 parts of Champagne chalk, 28.1 parts of kaolin.

c) 25 parts of active substance, 2.5 parts of isooctylphenoxy-polyoxyethyleneethanol, 1.7 parts of Champagne chalk/hydroxyethyl cellulose mixture (1:1), 8.3 parts of sodium aluminium silicate, 16.5 parts of kieselguhr, 46 parts of kaolin.

d) 10 parts of active substance, 3 parts of a mixture of the sodium salts of saturated fatty alcohol sulphates, 5 parts of naphthalenesulphonic acid/formaldehyde condensate 82 parts of kaolin.

The active substances are intimately mixed in suitable mixers with the additives, and the mixture is then ground in appropriate mills and rollers to yield wettable powders which can be diluted with water to give suspensions of the desired concentration. Such suspensions are very suitable for treating plants to influence growth and development.

Emulsif able concentrate: The following substances are used to produce a 25% emulsifiable concentrate: 25 parts of active substance, 2.5 parts of epoxidised vegetable oil, 10 parts of an alkylarylsulphonate/fatty alcohol polyglycol ether mixture, 5 parts of dimethyl formamide, 57.5 parts of xylene.

By diluting such a concentrate with water it is possible to manufacture emulsions of the desired concentration, which are suitable for application to plants for inhibiting growth.

The use of the active compounds in the form of dusts, tracking agents, wettable powders and emulsifiable concentrates, as well as frost-resistant solutions and aerosols, is particularly preferred.

The compounds of the formula I which are absorbed by plants and not prematurely metabolised and effect a slight growth inhibition without being noticeably phytotoxic, therefore best fulfill the expectations which can be placed in frost protectives.

The protective action of the compositions of the invention against frost was determined and evaluated by means of the following tests: I ) Frost-resistant test on beans Bean plants of the Felix variety were reared in a greenhouse in earthen-ware pots and sprayed with an aqueous preparation of the active compounds listed hereinafter at the commencement of flowering. The concentration of active compound in the spray broth was 1000 ppm. Eighteen plants were sprayed per treatment. Untreated plants were used as controls. Seven days after the application the test plants were placed in a climatic chamber, the temperature was slowly lowered to -l C, kept thereat for a brief time, and thereafter slowly raised again to room temperature.Evaluation was made 10 days after this cold treatment and each plant was inspected for frost damage using the following evaluation scale: - = all plants withered (as control)

(+) = + = # intermediate stages +++ = all plants without any trace of frost damage.

Results

Compound Frost-protective action 1 (+) 2 (+) 4 (+) 8 + 10 + 11 + 29 + 35 (+) 36 (+) 37 ++ 38 (+) 39 + 40 ++ 41 + In another test the bean plants were treated twice with a preparation of compound I, namely (a) twice at a concentration of 100 ppm and (b) twice at a concentration of 500 ppm. One week after the second treatment, the plants were exposed for 1 hour to a temperature of -4"C and then restored to normal.

conditions.

The test was evaluated one week later. Whereas the damage to untreated bean plants was 100%, i.e. total, the frost damage to plants treated with active substance at a concentration of 100 ppm was 40% and only 15% to plants treated with active substance at a concentration of 500 ppm.

2) Frost-resistant test on citrus plants Citrus trees were treated with compound 1 in the concentrations indicated below one day before a frost predicted in a weather forecast. in the hollowing night the temperature fell for 4 to 5 hours to -30C. Six days later the following results of the damage caused could be determined::

Treatment with spray Hamlin oranges and Valencia oranges broth % age damage to Compound 1 concentration in old leaves new leaves blossoms 500 0 80 60 1000 0 70 60 1500 0 70 60 untreated 0 90 90 3) Frost-resistant tests in fruit cultures a) For these tests, devices (cages) were used which make it possible to produce frost conditions on individual branches of a pear tree. Compound I was sprayed on blossom-bearing branches of pear trees at a time when the blossoms were just on the point of opening, viz. at the time of the greatest susceptibility to frost.Some days after this spray treatment, "cages" were placed over the treated and untreated branches of the same tree and then, at night, a frost with a minimum temperature of -3 C was artificially produced in these cages. A few days later the frost damage to the blossoms was determined by microscopic examination and the following results were obtained: treatment with 2000 ppm of compound 1 = 74% damage treatment with 4000 ppm of compound 1 = 26% damage untreated branches = 97% damage b) Peach trees were sprayed in the autumn with a liquid preparation of compound I just as the leaves were beginning to turn in colour and wither.In January, branches were collected and subjected for 24 hours to a cold treatment in the course of which the temperature was lowered stepwise by 2"C an hour to a minimum temperature of -21 0C and then raised again. The microscopic examination of many buds (embryos) was made two days later in order to ascertain how many had perished and how many had survived.

Result %age of surviving buds treatment with 1000 ppm 74% treatment with 2000 ppm 83% treatment with 8000 ppm 88% untreated 63% WHAT WE CLAIM IS: 1. A method of protecting plants or plant parts against frost damage which comprises applying to the plants or plant parts to be protected just before the onset of or during winter but at least one day before a suspected outbreak of frost a compound of the formula I

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. below one day before a frost predicted in a weather forecast. in the hollowing night the temperature fell for 4 to 5 hours to -30C. Six days later the following results of the damage caused could be determined:: Treatment with spray Hamlin oranges and Valencia oranges broth % age damage to Compound 1 concentration in old leaves new leaves blossoms 500 0 80 60 1000 0 70 60 1500 0 70 60 untreated 0 90 90 3) Frost-resistant tests in fruit cultures a) For these tests, devices (cages) were used which make it possible to produce frost conditions on individual branches of a pear tree. Compound I was sprayed on blossom-bearing branches of pear trees at a time when the blossoms were just on the point of opening, viz. at the time of the greatest susceptibility to frost.Some days after this spray treatment, "cages" were placed over the treated and untreated branches of the same tree and then, at night, a frost with a minimum temperature of -3 C was artificially produced in these cages. A few days later the frost damage to the blossoms was determined by microscopic examination and the following results were obtained: treatment with 2000 ppm of compound 1 = 74% damage treatment with 4000 ppm of compound 1 = 26% damage untreated branches = 97% damage b) Peach trees were sprayed in the autumn with a liquid preparation of compound I just as the leaves were beginning to turn in colour and wither.In January, branches were collected and subjected for 24 hours to a cold treatment in the course of which the temperature was lowered stepwise by 2"C an hour to a minimum temperature of -21 0C and then raised again. The microscopic examination of many buds (embryos) was made two days later in order to ascertain how many had perished and how many had survived. Result %age of surviving buds treatment with 1000 ppm 74% treatment with 2000 ppm 83% treatment with 8000 ppm 88% untreated 63% WHAT WE CLAIM IS:

1. A method of protecting plants or plant parts against frost damage which comprises applying to the plants or plant parts to be protected just before the onset of or during winter but at least one day before a suspected outbreak of frost a compound of the formula I

or a compound of the formula Ia

wherein R, represents a substituted or unsubstituted alkyl group of 1 to 17 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, an alkenyl group of 2 or 3 carbon atoms, or a substituted or unsubstituted phenyl group, R2 represents a hydrogen atom or a substituted or unsubstituted alkyl group of 1 to 4 carbon atoms, and R3 represents a hydrogen atom, a methyl group, an alkylcarbonyl group of not more than 11 carbon atoms in the alkyl moiety, an unsubstituted or substituted phenylcarbonyl group, a methylcarbamoyl group, an amine or ammonio cation or a metal cation of the formula 1/n (wherein M is a metal atom and n is its valency).

2. A method according to claim 1 for protecting a culture of fruit, vegetables or ornamental plants.

3. A method according to claim 1 or 2 in which there is applied a compound of the formula I or Ia in which R, represents a phenyl group or a straight-chain or branched alkyl group of 3 to 8 carbon atoms, R2 represents a hydrogen atom or a methyl group, and R3 represents a hydrogen atom, an alkali metal cation or a methyl, alkylcarbonyl or phenylcarbonyl group.

4. A method according to claim 1 or 2, wherein there is applied n pentanecarbohydroxamic acid of the formula CHa(CH2)aCO-NHOH.

5. A method according to claim 1 or 2, wherein there is applied 2-methyl propane-2-carbohydroxamic acid of the formula

6. A method according to claim I or 2 wherein a compound of the formula I or of the formula Ia specifically identified herein is applied.

7. A method according to any one of the preceding claims, wherein the compound of the formula I or of the formula Ia is applied in the form of a composition.