CA1056204A - Process for the promotion and facilitation of fruit abscission - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The invention is a process for the promotion and facilitation of fruit abscission, which process comprises the treatment of the fruit-bearing plants or of the fruit itself with an effective amount of a compound of the general formula I
(I) or with a non-phytotoxic salt of such a compound, the symbols in this formula having the following meanings:
R1 is hydrogen, halogen, an alkyl radical having 1 to 17 car-bon atoms, an alkenyl radical having 2 to 5 carbon atoms phenylalkyl or .alpha.'-furyl;
R2 is hydrogen, C1 to C17 alkyl, cycloalkyl, phenyl, carboxy carbalkoxy, carbanilido, a heterocyclic radical such as pyridyl and furyl, or a group

Description

~056ZID4 The present invention relates to a process for the promotion and facilitation of fruit abscission, preferably of citrus fruits, as an aid to the harvesting thereof, An improvement of fruit abscission, i.e. an appreciable reduction of the picking force to be applied in manual and mechanical harvesting, brings with it great advantages and renders possible appreciable simplifications in the harvesting of large-scale crops; fruit-bearing trees and shrubs are saved from damage due to the tearing away of branches and leaves; and there is a considerable economy of labour.
10 Various abscission agents have already been suggested, but ~hese are frequently unsatisfactory on account of undesirable side-effects, An example of these is cycloheximide, which, in spite of an excellent abscission action in the case of citrus fruits, has a great disadvantage in that it severely damages blossom and unripe fruit on the tree, has a pronounced defoliating action, and gives rise to considerable scarring on ripe fruit.
A further abscission agent to have received mention is ~-chloro-, * *
ethyl-phosphonic acid ("ETHREL", "ETEPHON"), which however, owing to too great a defoliating action, does not always satisfy requirements made of it.
The surprising discovery has now been made that certain oximes, oxime derivatives and their salts do not have the disadvantages of the abscission agents hitherto known, and are extremely suitable as agents for the promotion of fruit abscission The process according to the invention for the promotion and facilitation of fruit abscission comprises the treatment of the fruit-bearing plants with an effective amount of a compound of the general formula I

R R
l \ / 2 (l) or with a non-phytotoxic salt of such a compound, the symbols in this formula having the following meanings:
Rl is hydrogen, halogen, an alkyl radical having 1 to 17 carbon * 2 C trademark - -~ :

atoms, an alkenyl radical having 2 to 5 carbon atoms, phenylalkyl or ~ '-furyl;

R2 is hydrogen, Cl to C17 alkyl, cycloalkyl, phenyl, carboxy, carbalkoxy, carbanilido, a heterocyclic radical such as pyridyl and furyl, or a group /

~ (CH2) n~C

N-OR4 t wherein R'l has the same meaning as Rl, n is an integer from O to 3, Rl and R2 taken together form a C3-C12 ring, and R3 and R4 each independently represent hydrogen and radicals from the group consisting of Cl-C12 alkyl, C2-C5 alkenyl, alkylcarbonyl, phenylcarbonyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl N,N-dialkylcarbamoyl, phenylcarbamoyl, phenylalkyl, alkoxycarbonyl, phenoxycarbonyl, phenylalkoxycarbonyl, alkylthiocarbonyl, phenylthiocarbonyl, ~ -furyl and tetrahydropyranyl, with the proviso that when n is O, Rl and R'l are both hydrogen and R3 is hydrogen, Cl to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, alkyl-thiocarbonyl or tetrahydropyranyl, R4 is not Cl to C12 alkyl, C2 to C~ ~
alkenyl, phenylalkyl, alkylcarbonyl, phenylcarbonyl, N-alkylcarbamoyl, N- ~ :
alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, alkylthiocarbonyl or tetrahydropyranyl, and the further proviso that when n is 0, Rl and R'l are both hydrogen and R4 is Cl to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, alkylcarbonyl, phenylcarbonyl N-alkyl-carbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, althiocarbonyl or tetrahydropyranyl R3 is ~
not hydrogen, Cl to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, N-alkylcarba- ~ -moyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxy-carbonyl, phenoxycarbonyl, alkylthiocarbonyl or tetraphydropyranyl, The compounds of formula 1 are therefore oximes and dioximes, their 0-substituted derivatives and salts. Substituents on the oxygen atom C

. , ~ . , ' ,. : ~ . :

1056~0'~
(R3 and R4) are, as can be seen above, preferably such radicals which are readily split off hydrolytically, aminolytically or metabolically in the plant or in the application agent (spray emulsion) with the formation of the free oxime group (R3=R4=11).
Particularly suitable radicals for R3 and R4 are those used in synthetic chemistry as protective-groups of alcohols (acyl radicals, etc.).
Applicable substituents of substituted radicals Rl, R'l, R2, R3 and R4 are: halogen, the oxo group, alkoxy, phenoxy, dialkylamino, alkyl-thio, hydroxy, amino, nitro, N-pyrridylium, trialkylammonio, etc.
The compounds of formula I can be present as Ci5- and trans-forms.
Preferred compounds for the described field of application are the dioxime derivatives of formula II

1 ~ R'l C-(CH2)m-C / (II) wherein Rl and R'l each independently represent hydrogen, chlorine or methyl groups, m denotes the number 0, 1 or 2, and R3 and R4 represent hydrogen or unsubstituted or substituted alkylcarbonyl, phenylcarbonyl, alkylcarbamoyl, dialkylcarbamoyl, alkoxycarbonyl,phenoxycarbonyl,alkylthiocarbonyl, phenyl-thiocarbonyl or tetrahydropyranyl radicals.
Non-phytotoscic salts of these dioximes are also suitable, both the salts of strong acids and, if R3 and/or R4 is hydrogen, the salts of bases, such as the alkali metal salts and alkaline-earth metal salts~ as well as the salts of other bivalent and trivalent metals, such as Fe, Cu, Zn, Mn, Co and Al, and also the salts of strong amines.
Particularly preferred are glyoxime and derivatives of the glyoxime of formula III
CH CH

C _4_ wherein R3 and R4 each independently represent hydrogenJ al}ylcarbonyl, alkylcarbamoyl and alkoxycarbonyl, as well as salts of glyoxime.
To effect promotion of fruit abscission, particularly of cit-rus fruits, the fruit-bearing trees are treated 3 days to 4 weeks before the harvest with agents containing active substances of the above mentioned for-mulae or salts thereof.
The active substances used according to the invention are related to compounds not previously known and also useful for the facilita-tion and promotion of fruit abscission. The novel compounds are the subject 10 of our Canadian Patent Application Serial No. 220,722 filed on February 25, 1972 and divided out of this application. New active substances not hither-to described in the literature are, for example, glyoxime derivatives of the more restricted formula IV

CH CH
~ (IV) ; R'3-0-N N-0-R~4 wherein R'3 represents hydrogen, Cl to C14 alkyl, alkenyl, phenylalkyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbanoyl, phenoxycarbonyl, alkylthiocarbonyl or tetrahydropyranyl, and R'4 represents alkyl, alkenyl, phenylalkyl, alkylcarbonyl, phenylcarbonyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarba-moyl, alkoxycarbonyl, phenyloxycarbonyl, alkylthiocarbonyl or tetrahydropy-ranyl. The compounds of formula (IV) thus represent another aspect of the ~ -invention.
These compounds are produced in a known manner by a process in which glyoxime or a salt thereof is treated in a solvent such as aceto-nitrile, acetone, ether, etc., and optionally in the presence of an acid-binding agent, e.g. triethylamine, with an agent introducing the radical R'3 or R'4. Suitable agents are, for example, acetyl chloride, phenylisocyanate dimethylcarbamoyl chloride, methylbromideJ chloroformic acid ester, chloro-thioformic acid ester, benzylbromide, alkylisocyanates, alkylisothiocyanates,etc.

C

: . . . .

1(~56204 The following examples describe the preparation of some new oxime derivatives of formula I or IV. Further oxime derivatives which can be used as active substance for the process according to the invention are listed in the following tables. The temperatures are expressed in degrees Centigrade.

C

- lQS6Z04 Exam~le 1: Glyoxime - 0 - monoacetate.

1 Part of acetyl chloride is added dropwise at 0 to a solution of 1 part of glyoxime and 2 parts of triethylamine in S parts of acetonitrile. ~fter being stirred overnight at room temperature, the reaction mixture is concentrated by evaporation to dryness, taken up in water and extracted with ethyl acetate.
The organic phase is dried with magnesium sulphate and concentrated, whereby the product crystallises out as fine, white needles (mp. 124-6).

Exa~le 22: Glyoxime-0,0'-bis-phenylcarbamate. ~ -0.1 Mole of finely powdered glyoxime is suspended ;
in 100 ml of acetonitrile. After the addition of 0.2 mole of phenylisocyanate, stirring is maintained for ca. 15 ~
hours at 20. The fine, pasty precipitate is filtered off ~ ~-and dried in Vacuo; yield: g5%, mp. 180 (decomposition).

ExamPle 2b: Glyoxime-0,0'-bis-dimethylcarbamate.

2 Parts of dimethylcarbamoyl chloride are added dropwise at 30-35 to a solution of 1 part of glyoxime and 2 parts of triethylamine in 5 parts of acetonitrile.
The formed triethylamine-HCl is filtered off and the filtrate concentrated by evaporation. The residue is taken up in ethyl acetate and the solvent evaporated off.
The light-coloured, crystalline product decomposes on being dried in vacuo at 60; mp. 134 (decomposition).
- -æ

. ~
.. . . . . .

~ `~
lOS6Z04 Example 3: Glyoxime-O bis-methyl ether.
An e~cess of methylbromide is introduced into a solution of glyoxime-Na-salt at 0. After a stirring over-night, the precipitated Na Br is filtered off. From the filtrate there are obtained the desired product, mp. 225, and a secondary product, mp. 204.
~i Example ~: Glyoxime-O,O'-bis-ethylthiocarbonate.
2 Parts of chlorothioformic acid-S-ethyl ester are added dropwise at 0 to a solution of 1 part of glyoxime and 2 parts of triethylamine in 5 parts of acetonitrile.
A gas (C02) is evolved during the reaction. The reaction mixture is filtered off from triethylamine hydrochloride and the filtrate concentrated in vacuo. The oily : decomposable residue has a smell of mercaptan.

Example 5: Glyoxime-O,O'-bis-benzyl ether.
22 g of glyoxime is dissolved in 200 ml of 2.5N NaOH
at room temperature and 1 litre of acetone added to the solution, whereby the glyoxime-di-Na-salt precipitates.
This is dissolved in 10 parts of methanol and 2 parts of benzylbromide are added, whereon a slight exothermic reaction occurs. After several hours' stirring, dilution is performed with methylene chloride, the NaBr removed by filtration and, by concentration of the filtrate by evaporation, a white product, mp. 72, obtained (yield:
ca. 65%).
A ~

Example 6: 0,0-bis-tetrahydro-2-pyranylglyoxime.
An amount of 13.2 g of g]yoxime is suspended in 50.4 g of 3,4-dihydro-2H-pyran. After dilution with 50 ml of absolute tetrahydrofuran, 50 mg of dry HCl-gas is introduced. The mixture is heated at 45 until a solution is formed. This is stirred, without further heating, for 6 hours, and is then poured into 500 ml of saturated soda solution. After extraction of the soda solution three times with ether, and drying and concentration of the organic phases by evaporation, a yellow-brown oil is - obtained, which is dried in vacuo at 0.1 mm and 20;
yield: 33.3 g = 86.5%, nD0 : 1.5048. -~

Example 7: 0,0'-bis-isobutyroylglyoxime.
2 Parts of isobutyroyl chloride are added dropwise at 10 to a solution of 1 part of glyoxime and 2 parts of triethylamine in 5 parts of acetonitrile. Filtration is performed after 2 hours' stirring at 20; the filtrate is concentrated by evaporation, taken up in methylene chloride, and washed with water. The product, mp. 92, is obtained from the dried organic phase after concentration by evaporation and recrystallisation from ethyl acetate ;
~80% yield).

Ex~ Glyoxime-0-mono-N-methylcarbamate.
An amount of 0.4 mole of methylisocyanate is slowly added dropwise at 30 to a solution of 35 g of glyoxime A - ~qo -: :

1056Z~D4 in 1 litre of abs. ether. After being stirred overnight at 20, the reaction mixture is concentrated cold by evaporation to dryness. The residue is taken up in acetonitrile, and insoluble substance removed by filtration (bis-methylcarbamate); concentration by evaporation is then repeated. The dark residue (50 g) decomposes spontaneously on drying in vacuo at 40; mp. 40 (slow heating up).

,' Example 9: 0-Acetyl~0'-N-methyl-carbamoylglyoxime.
]0 1 P&rt of methylisocyanate is added to a solution of 1 part of mono-0-acetylglyoxime (Example 1) in 5 parts of acetonitrile, and stirring carried out for 4 hours at 20. The precipitated product is filtered off;
mp. 138; yield 90%.

Exam~le 10: --18.7 g of chloroacetaldoxime is dissolved in 200 ml of sulpholane and 50 ml of ether, and 19.8 g of pyridine added to the solution. The reaction mixLure is stirred overnight at 20, and the formed suspension filtered. The residue is dried in vacuo at 12 mm Hg and 20 for 16 hours; yield: 33.2 g = 97%; mp. 100-110.

Example 11: Glyoxime-0,0'-bis-methylcarbonate.

2 Parts of chloroformic acid methyl ester are added dropwise at 0 to a solution of 1 part of glyoxime and .
~ - ~,1. -los62al4 2 parts of t~iethylamine in 5 parts of acetonitrile.
After completion of the reaction, the precipitated product is filtered off and the residue stirred with water. A white product, mp. 225 (decomposition), is obtained after filtration and drying.
,~
Exam~ Glyoxime-O,O'-bis-N-methylthiocarbama~e.
2 Parts of methylisothiocyanate are added to 1 part of glyoxime in 10 parts of acetonitrile. After some time, a spontaneous heating to 40 occurs, whereby the reaction mixture becomes reddish. After a stirring time of several hours, the solvent is evaporated off: a red-brown oil is obtained (n20 : 1.595).

Example 13: Preparation of zin -bis-(glyoxime).
2.3 g (0.1 mole) of Na is dissolved in 50 ml of methanol(abs.), and the solution, after completion of the reaction, heated to boiling. With continuous stirring and refluxing, an addition is slowly made dropwise of 6.8 g (0.05 mole) of ZnC12 in 100 ml of methanol. The solution is cooled and the precipitated sodium chloride filtered in a separating funnel by the solution being pressed with N2 through a glass suction filter. Washing is then performed twice with 20 ml of methanol. A solution of 8.8 g (0.1 mole) of glyoxime in 100 ml of methanol is placed into a flask and, with gentle heating, the solution of Zn (OCH3) added dropwise. The precipitate is filtered off , ~

~nd dried: 2.~ g, Zn content 36 8%, mp.~ 250. After standing for 4 hours, the mother liquor is concentrated to ca. 80 ml. Trituration w:ith a spatula is performed and a nicely crystallised substance commences to precipitate. It is filtered, washed and dried;
- yield: 6.0 g; Zn content: 28.3%, mp. ~ 300.

Example 14 An amount of 2.4 g of magnesium powder is suspended in 50 ml of absolute methanol, and the suspension stirred until no further hydrogen is liberated. An addition is then made dropwise o:E 8 . 8 g of glyoxime in 100 ml of methanol. After 30 minutes, the methanol is evaporated off in vacuo. Residue 11.0 g of magnesium glyoximate, mp. ~ 220.

The preparation of the calcium salt and aluminium salt, respectively, is effected by the same procedure, with calcium hydride or aluminium being used instead o E magnesium.

- . ~ , : : `
105620~ ~

No Formula physical constants . . . bPX = boiling pointC a~ x T~r mp. = mel~ing point ,,~ ,., .. ... , ,__ . ., 1 Cri3(C~i2)3C(CII3)=NOIi bPll 65 . 2 (c~i3)3cc(cH3)=N-oll mp. 75

3 C l~ C(CH )=N-OH mp, 43 . 13 ~I (C2~5) N OH mp. ~0 S C5Hll-cH=N-oH mp. 51 6 (C}3~)2C=N-OH mp. 61 7 C2H5(CH3)C=NH bp. 25 70-78 8 (C~3)2C=N-OCOCIi2cH2-cOoll ? rnp.
9 1CH2=N-O~-}IC1] :
mp. 135 (decon]p.) C}l3-cH=N-Gll bp. 113-115 11 (Cll~)2c-cscc ~ . mp. 17~I

12 2H5 C~ -CO-O-c~2-cH2-cl C~3 . .
13 (n-C~Hg)2C=N-OH bp. 15 125 14 lI 35 2 mp. 65-66 1.5 (C~ C-C(n-C3H7)-N-OH rnp. 5 .. .. .. ,, , .. ,.. ., ., -- , : . ~ ~ :
, .
- : :

lOS6204 . ~
Compound Formula Physical consl:ants No. bPX =boilin~ pointC at x Torr mp. = melting point . _ __ . _ ~ . . _ 16 (CH~C=N-OH mp. 1~5 17 l(CH~C=N-Oi-l) mp. 56-5~ .

1~3 I(CH~C=N-OI1] mp. 90 ~N-OI-I ¦ mp. 118 [t,~;~CH=Ci~-CH=J\I'-OH ] P 12 65 21 1CC13-C]I=N-OH) P 12 74 22 1 ~c~2-cl~=N-o~] mr). 103 23 1CH3CO-C(CH3)=N-OH] ~ mp, 78 24 [CH3CO-CII=N-OH] mp. 69 CN CH2 CH=N OH mp. 110 26 1~o2-cll2-cH=N-oNa mp. 200 (decomp) (methazonic acid) 27 [Cl-CH2-CH=N-OH ] bp. 70 (decomp.) 28 C2H500C_cH=N_ol~ mp. 5 3 5 5 29 [(CH3)21`~_CH2 CH=N O~I] bp.~8 105 [c~3-s-cl~2-cl~=N-oH ~ bp. 1 56-5~
. '.''' ` ---~ 1056204 . .. ~
Compound Formula Pllysica1 constants .: bPX = boiling pointC at . x Torr . mp. G melting point . __ __ .. . _ . _ _ _ _ . .

l H~-Cll2_cll=N_oll ~ mp. ~l8-50~ (decom4 32 ~ )2C~-c(c~3)=NoH mp. 162 ¦ 3 ¦130-l~=C (C~l )-Cll- ~Cl ~ mp. 135 34 ~ ,C;-C~I=N-013 mp . 126-128 O : .

~ NH-c-cH-N-o~l mp.

36 ~C-c(c~l3)--N-o}I mp. 1].3-115 37IIIOOC-C(CI~3)=N-O~I ] mp. 1~0 -~ :
3~¦ N aOOC-C (CH;~, )=N -0~1~ mp - 340 ;
39 I~OOC-CH=N-OII 14l~0 ( 2 ) @~N-oH mp. 122 .
~C -iI
41 ~N l~-OII mp. 109-112 .:

4 2 ~,J_ CH=NOH mp, ~38 _ ~0 .
Cl' ' ~.
43 ~,/? C~l=NOH mp. 130-1~)8 :1 , ., : .

~ 1056204 . . . . . ~
Compound Fo rmula Phys i c a 1 c on s t an t s No. bPX -boiling point C a~:
x Torr mp . -- me 1 t ing point _ . _ . _ _ _ _ 4 4 02N -O- CT I .-NOH
mP. 129-134 ~ C1-~O~-C 7 N 017 ~ mP. 110 4 6 CH, O ~ _ C~ 3_N ~
OCI-13 mP . 213-211i I 7 ¦ <O} C772 5 ~ bP 100 /

4 8 HON=CH - ( CH2 ) 2CT~=N -0;1 n~P . 152-154 4~ I~ON-C (CH ~)CH2-C (CH;~)C=N-OTI] mP. 1()8-170 1H-O-I~J=C (C1 )CH=N-O~I ] - mi>. 144 51 ~IO-N=C (C1 ) -C (C1 )--NOT1 mP . 201 52 HO-~ =C (CH3)C (CJ~3)=N OH mp. 24() 53 ¦HON=C (Cll3) -C (C] )=N-OI-I ] mp . 187 54 ICT~3COON-CH-C(C1)--N-OCOCTI;5 ~ mp 91-93 mP. 11~
(EJ Z Isomeres ) ( 2 )3 CH N OT~ mP. 170-1~0 .- . . .
56 HON = CH-!C =NOII mP. 157 . CH3 ... . . . .......... ............ _ . .. . .... . .. . . ._ .

. . .
. . ~. .

. ~ _ . .. .. . ~
Compound Formula Physical const:ants .. bPX - boiling pointC at . mp. - mel.ting point .~
57 [ Cl13COO -N=C}i -Cl l -. N -OCOCI-i3] mp . 125 58 CH3COO-N=Cf-l-CH=N-()H mp . 120-124 ~econ:, ~ ~ :

59 [ ic3~7cooN=cll_cll_N_OcOc ll ] mp. 92 :-[C6H5COON=CH_cH=N_ococ6H 3 mp. 172-170 :
61 [C11l123COON ClI-CH=N-ococ H ] mp. ].00-105 62 [CTl~111COO-N--CH-CII=N-O-CONHCH3] mp. 136 63 [ C~}~9NHCOO-N=CH-CH-NOC()NHCl~Hg ] mp. 112~

64 CH 50-'N=C}I-CH=N-OC~3 mp.~ 215 - :
1 C6H5NHCOO-N=C}I-CII=N-OCONH-C~H5] mp. 1~0 ::
66 6~CH3-o-c6H4-coo-N=cH-c}~=N-ooc6~ )CH3] mp; 200-205 67 HO-N=CH-CH=N-OH mp. 172 . .

68 12H25 O-N=C~-C~I=N-O-C12H25 mp. 59 :: ~
69 CH2=CH-CH2-0-N=CH-CII=N-O-CH2-CIl= C~l2 mp. 20 ~. ;

CH3-'NH-CO-O-N_CH-CH_N-OH mp. 40 (D~colnp. ) 71 ~ Cl 12 - O -N=CH -C}l=N -OCH2 -~ mp . 72 72 CH3-COON=CH-C}I~N-OCONHCH~; mp. 13~3 73 CH3COO-N=CH-C~I=N-OCONH-C6H5 mp. lG4 ~ . . . ~ .
. Compound Formula Pl~ysical constan~.s : No. l~p = boiling pointC at . mp. melting point . ................... _ . _ . ._ 74 C2HsGcoo~ H-cll~N-ocooc2~l5 (cH3)2c~l-c~l2ocoo-N-cH-cl~ -ocoo-cll2-cll(cH3)2 mp. 94 76 ~ C112-0-cOO.. ,l=cllc~l=N

77 /~0-COO-N=C11-C11~N-OCOO~r~

78 C~l3o-~l2cil2-ocool~-c~l-cll~N-ocoocH2c~l-Oc~l .

79 Br-cll2cll2ocooilcll-cl~l!-ocoocll2cll2-Br C112(:~1-C~12-OCOO-~i=C1J-C11=1~-OCOOC~i2-C11=C;12 .

8l C1130C00,1-C11-C1~ -0-COOC~13 ~1p, 22~

82 (CH3)2~COO-N=CH-C11=N-OCO,'(CH3)2 mp. 134 83 C2llsscoo-Nc~lc~ ocosc2H5 red oil 84 ~O}S_COO!I=CII-CHNOCOS- ~

~ojoN=cHcH=lJoloJ n~ = l,504 86 CH3NHCS-0~ CI~-CH=M-OSSI~IICI~3 nD = l, 595 87 ( HO-N=CH-CH-N-OH
mp,> 200 . ~I~`e salt 88 Zn sal~ mp. > 260 89 Mn salt mp. > 260 Co salt mp. > 260 91 Cu salt mp- > 2C0 92 Na2 sal t ~p . > 250 - 18 - .

_._ . ... . _ .
Compound Formula Physical constants No. bPX = boiling pointC at x Torr mp. melting point . _. _ 93 ethanolamine-salt viscous oil 94 Ca salt mp. > 250~

Mg salt mp. > 250 -96 Al salt mp. > 250 97 ~ CH-C- ~ mp. 153~155 OH NOH

98 ~ C-C ~ mp. 166-169 HON NOH

99 C2H5C(CH3)=N_C_NH_cH2 CH2C L
. .. I

100 ~ CH-N-O-C-O-CH CH C L

-19_ ~ \

The active substances of formula I are not phytotoxic in the usual application concentrations, and they have low toxicity towards warm-blooded animals. They moreo~er produce no morphological changes of the plants or cause damage to them.
They promote, in particular, the development of abscission layers, particularly between stalks and petioles. Consequently, fruits of all kinds, e.g. stone fruit ~cherries), berries, grape vines, pomaceous fruit (apples) or oil fruits (olives), and particularly citrus fruits such as oranges, lemons, grapefruit, etc., can be separated from the fruit stems, manually or mechani-cally, without any great amount of force being applied. Damage to foliage and branches which normally occurs when fruit is removed by the shaking of trees and shrubs, or by the plucking of the fruit from the branches, is large-ly avoided, and the production capacity of the trees thus increased.
~ The extent and nature of the action are governed by the most di-verse factors, depending on the type of plant, particularly, however, on the applied concentration and on the time of application with regard to the stage of development of the plant and the fruit. Thus, for example~ plants of which the fruit is to be sold, or in some other way utilised, are treated immediate-ly after blossoming or at an appropriate length of time before the gathering of the fruit. The active substances are applied preferably in the form of liquid preparations, these being applied to parts of plants above the soll, to the surface of the soil or into the soil. Application to parts of plants above the soil is preferred, for which purpose solutions or aqueous disper-sions are most suitable.
The active substances of formula I are used together with suitable carriers, solvents and/or other additives. Suitable carriers and additives can be solid or liquid, and correspond to the substances normally used in formulation practice, such as, e.g. natural or regenerated mineral substances, :, sblven~s, dispersing agents, wetting agents, adhesives and thickening or bonding agents.

- 1 9~ -C

~056Z04 The applied amounts are largely governed by the purpose and nature of the application (treatment of the soil or of parts of plants). The usual amounts applied in the case of soil treatment and for crops are between 0.1 and 10 kg of active substance per hectare of land under cultivation.
The agents for promoting abscission which contain active sub-stances of formula I can be formulated as aqueous or non-aqueous solutions and dispersions, emulsifiable concentrates, wettable powders or dusts, option-ally with additional amounts of antioxidants, such as hydroquinone. Such formulations can contain 2 to 95 per cent by weight, preferably 80 to 90 per cent by weight, of active substance, and can be prepared by the techniques normally applied in agricultural chemistry.
Preferred preparations are aqueous ones having a content of 0.1 to l~ of a nonionic wetting agent.
About 0.1 to 16 kg, preferably l to 4 kg, of active substance is employed per hectare of area under cultivation.
The time of application to promote fruit abscission is shortly before harvesting, i.e. 3 days to 4 weeks before harvesting.
The determination of the abscission action on citrus plants was made by the following methods:
A.) On freshly sprouted branches of Citrus sinensis var. Volkameriana, the leaf surf~ce was cut off from 8 leaves, leaving only the leaf-stalks on the branch. Two such branches in each case were then sprayed with active-substance solutions of 4000 and 2000 ppm active-substance content, respective-ly. The test was evaluated after 7 days on the basis of the number of shed leaf-stalks. In all the control tests, no leaf-stalk was shed.
B.) Parts of branches of orange trees (variety Hamlin or Pineapple or Valencia) carrying at least 20 oranges were sprayed with active-substance solutions shortly before harvesting. The evaluation of the test results was made after 7 days, with two different systems being employed:

a) Measurement of the plucking force and determination of the reduc-C
_ . - ' , ' ' ' .

' tion thereof effected, with respect to the untreated control specimens.
b) Number of shed oranges (without shaking) in per cent, compared with the untreated control specimens (0O).
All active substances tested produced, with no or negligible shed-ding of leaves, an intense development of abscission layers on the fruit-stal~s,an appreciable reduction of plucking force, and some of them even good values with regard to the shedding of fruit.
" Especially good results have so far been obtained with compounds Nos. 8, 17, 42, 67, 97 and 98.
! 10 In the case of Hamlin oranges with a 4000 ppm concentration of active substance 0-(2-chloroethoxycarbonyl)-butaneoxime, the plucking forces required after 7 days were less than a quarter of those required for untreated oranges, these being 9 to 11 kg per orange. Similarly good reductions in plucking force were obtained with dichloroglyoxime, whilst the plucking forces on application of glyoxime and N,N-die.hylhydroxylamine decreased already .rith 500 ppm to practically zero, i.e. shedding of fruit occurred.

a ~
. .. . ~
. .. .

Claims (10)

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

1. Process for the promotion and facilitation of fruit abscission, which process comprises the treatment of the fruit-bearing plants or of the fruit itself with an effective amount of a compound of the general formula I

(I) or with a non-phytotoxic salt of such a compound, the symbols in this formula having the following meanings :
R1 is hydrogen, halogen, an alkyl radical having 1 to 17 carbon atoms, an alkenyl radical having 2 to 5 carbon atoms phenylalkyl or .alpha.'-furyl;
R2 is hydrogen, C1 to C17 alkyl, cycloalkyl, phenyl, carboxy carbalkoxy, carbanilido, a heterocyclic radical such as pyridyl and furyl, or a group wherein R? has the same meaning as R1, n is an integer from 0 to 3, R1 and R2 taken together form a C3-C12 ring, and R3 and R4 each independently represent hydrogen and radicals from the group consisting of C1-C12 alkyl, C2-C5 alkenyl, alkylcarbonyl, phenylcarbonyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl N,N-dialkylcarbamoyl, phenylcarbamoyl, phenylalkyl, alkoxycarbonyl, phenoxycarbonyl phenylalkoxycarbonyl, alkylthiocarbonyl, phenylthiocarbonyl, .alpha.-furyl and tetrahydropyranyl, with the proviso that when n is 0, R1 and R? are both hy-drogen and R3 is hydrogen, C1 to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, alkylthiocarbonyl or tetrahydropyranyl, R4 is not C1 to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, alkylcarbonyl, phenyl-carbonyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, alkylthiocarbonyl or tetra-hydropyranyl, and the further proviso that when n is 0, R1 and R? are both hydrogen and R4 is C1 to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, alkyl-carbonyl, phenylcarbonyl N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkyl-carbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl,alkylthiocarbonyl or tetrahydropyranyl R3 is not hydrogen, C1 to C12 alkyl, C2 to C5 alkenyl, phenylalkyl, N-alkylcarbamoyl, N-alkylthiocarbamoyl, N,N-dialkylcarbamoyl, N-phenylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, alkylthiocarbonyl or tetra-hydropyranyl.

2. A process according to Claim 1 wherein R1 is chlorine.

3. Process according to Claim 1, wherein the active substance em-ployed is a compound of formula II

(II) wherein R1 and R? each independently represent hydrogen, chlorine or methyl, m denotes the number, 0, 1 or 2, and R3 and R4 each independently represent hydrogen or alkylcarbonyl, phenylcarbonyl, alkylcarbamoyl, dialkylcarbamoyl, alkoxycarbonyl, phenoxycarbonyl, alkylthiocarbonyl, phenylthiocarbonyl or 2-tetrahydropyranyl radicals.

4. Process according to Claim 3 wherein amine salts, alkali metal and earth-alkaline metal salts, as well as the salts of Fe, Cu, Zn, Mn, Co or Al of a compound of formula II in which R3 and/or R4 denote(s) hydrogen, are employed.

5. Process according to Claim 1 comprising the use of a compound of formula III

(III) wherein R3 and R4 each independently represent hydrogen, alkylcarbonyl, alkyl-carbamoyl or alkoxycarbonyl.

6. Process according to Claim 5 wherein glyoxime or a non-phyto-toxic salt thereof is employed.

7. Process according to Claim 1, 2 or 3 for the promotion and facilitation of fruit abscission of citrus fruits, in which process the citrus fruit-bearing plants are treated, 3 days to 4 weeks before harvesting of the fruit, with an effective amount of a compound of formula I or II, or of a salt of such a compound.

8. Process according to Claim 1 comprising the treatment of cit-rus trees with glyoxime.

9. Process according to Claim 1 wherein dimethyl glyoxime or a non-phytotoxic salt thereof is employed.

10. Process according to Claim 1 wherein dichloroglyoxime or a non-phytotoxic salt thereof is employed.