Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
0 90 3 ~ ~
The present invention relates to novel phenoxyphenoxy-
alkanecarboxylic acid derivatives having a herbicidal
and plant growth regulating action, processes for their
production, compositions which contain these derivatives
as active ingredient and to a method of controlling or
regulating undesirable plant growth which comprises the
use of the novel c~lpounds.
The phenoxyphenoxyalkanecarboxylic acid derivatives of
the invention have the formula I
N02 O-~-A
4 ~ _0 ~ R2 (I)
wherein
Rl represents hydrogen, Cl-C4alkyl or C2-C8alkoxyalkyl,
R2 represents hydrogen or Cl-C4alkyl,
R3 represents halogen, cyano or nitro,
R4 represents halogen, cyano or trifluoromethyl,
A represents cyano or the group -COB,
B represents a radical OR5, SR6 or NR7R8,
R5 represents hydrogen or the cation of a base n M n ~,
wherein
M represents an alkali metal or alkaline earth
metal cation or an ammonio radical
.
... ... . . ..... ........... . ....... .... . .. . . .. .. .. . .. .
~~' 10 ~0 3~7
-- 2 --
R - N R
R R
b c
n as integer 1, 2 or 3 corresponds to the
~alency of the cation, whilst Ra, Rb, Rc and Rd,
each independently of the other, represent
hydrogen, benzyl or an alkyl radical which is
unsubstituted or substituted by -OH, -NH2 or
Cl-C4alkoxy; and R5 further represents
-a Cl-C8alkyl radical which is unsubstituted or
substituted by halogen, cyano, nitro, hydroxyl
or a 5- to 6-membered nitrogen- containing
--- heterocyclic ring system, and a C2-C8alkyl
radical which can be interrupted by oxygen, ~
sulphur, nitrogen, carbonyl or carbonyloxy, .
-a C3-C6cycloalkyl radical,
-a C3-C6alkenyl or alkynyl radical which can be
substituted by halogen,
-a phenyl or benzyl radical which can be substituted
by halogen, cyano, nitro, Cl-C4alkyl, Cl-C4alkoxy
or trifluor~methyl,
R6 represents a Cl-C8alkyl radical which can be
substituted by halogen, cyano, nitro or hydroxyl or
interrupted by oxygen, sulphur, nitrogen, carbonyl
or carbonyloxy,
a C3-C6cycloalkyl radical,
a C3-C6alkenyl or alkynyl radical which can be
substituted by halogen,
a phenyl or benzyl radical which can be substituted
by halogen, cyano, nitro, Cl-C4alkyl, Cl-C4alkoxy
or trifluoromethyl,
R7 represents hydrogen, a Cl-C8alkyl radical which can
- . -
- - .. . . ~ ~ - ~ .
,
- ~. ~ . . .
- ::
10903~
_ 3 _
be substituted by halogen, cyano or hydroxyl, and a
C2-C8alkyl radical which can be interrupted by oxygen,
R8 represents a Cl-C4alkyl radical or a C3-C4alkyl
radical, and
R7 and R8, together with the nitrogen atom to which they
are attached, also represent a 5- to 6-membered
heterocyclic radical which can be interrupted by
oxygen, sulphur, an imino, Cl-C4alkylimino or phenyl-
imino group. ~ -
In the above formula, the alkyl radicals are both
branched and unbranched and contain the indicated number
of carbon atoms. The symbols R7 and R8 preferably re-
present hydrogen or lower alkyl groups. Individual alkyl
groups however can also be unsaturated or aromatic
(phenyl) or araliphatic (benzyl) and both together with
the nitrogen atom to which they are attached can form a
5- to 6-membered heterocyclic ring system.
Herbicidal active c~mpounds based on substituted di-
phenyl ethers are known, for example from Swiss patent
specification 424,326. Recently, herbicidally active
phenoxyphenoxyalkanecarboxylic acids have been described,
in which connection attention is drawn for example to
German Offenlegungsschrift 2,433,067.
The present invention provides a novel group of phenoxy-
phenoxyalkanecarboxylic acid derivatives which, in low
rates of application, are able to influence the growth of
plants in a manner which is agriculturally advantageous.
The novel active compounds of the formula I of the present
invention possess a general herbicidal action which is
non-specific to grasses, especially on post-emergent
application, and they can be used as weed kill~rs in
`` 10 90 36 7
crops of mono- and dicotyledonous plants.
The active compounds also possess an advantageous growth-
regulating action (growth inhibition).
In particular, they inhibit the growth of
dicotyledonous plants. Exemplary of the useful applica~ion
of the compounds of the present invention are:
- the reduction of the vegetative growth in soya and
similar leguminosae, resulting in an increase in the
yield of these plants;
- the inhibition of the undesirable growth of suckers in
tobacco plants, the leading shoots of which have been cut,
thus promoting the fonllation of larger and finer leavesi
- the inhibition of the growth of grass and dicotyledonous
~ plants, such as fruit trees, ornamental trees, bushes ~nd
hedgerows, with the object of saving cutting work.
The compounds of the present invention have a low
toxicity to warm-blooded animals and their application
causes no problems. The rate of application is between 0.1
and 5 kg per hectare.
The novel compounds of the formula I are obtained by
reactions of chemical synthesis which are known per se,
for example in accordance with the following reaction
scheme:
. ' ..
: .
: :
-. ~
: . : . : : :
- : "~
- 1()903t~7
_ 5 _
NO2 ~1 NO2 OH
R4 ~ ~1 + HO ~ __,~R~ ~ O _
~ C12 1 ~3
NO2 OH ~ 2 ~
4~ ~ O ~ Cl R4 ~ ~ -~2
Rl
Hal - C - A
R2
~ Rl / Rl
NO2 OC-A NO2 OC-A
R ~ ~ 2 R ~ ~ 202
In the above formulae, Hal is a halogen atom, preferably
a chlorine or bromine atom, and A, Rl, R2 and R4 are as
defined in formula I.
Ortho-nitrochlorobenzene substituted in the para-position -
by the radical R4 is reacted with resorcinol at elevated
temperature in the presence of an acid acceptor. There
should be a slight excess of resorcinol over the chloro-
benzene. When the reaction is complete, the
reaction mass is poured into water and the
resulting diphenyl ether is extracted from the aqueous
suspension with a solvent which is not miscible with
water. A trace of copper powder can be added to hasten
10903ti7
6 -
the condensation. The condensation is advantageously
carried out in an oil bath at about 200C. Attention is
drawn to the following literature: Weygand Hilgetag,
"Organisch-Chemische Experimentierkunst, 3rd edition
1964, 435, US patent specification 3,080,225, German
Offenlegungsschrift 2,433,066, and German Auslege-
schrift 1,187,852.
A nitro group can be introduced into the still free para-
position of the diphenyl ether by nitration in glacial
acetic acid, ethylene chloride or sulphuric acid. A
chlorine at~m can be introduced into this position by
treatment with chlorine in glacial acetic acid. If R3 is
cyano or bromine, the chlorine atom is replaced in this
stage for example by reaction with KCN (see Adv. Chem.
Ser. 132 (1974), 252, or J. Organomet. Chem. 54 (1973)C
57) or KBr or NaBr, or the aniline obtained by reduction
of the N02 group is subjected to a Sandmeyer reaction.
The process of the invention for the production of
phenoxyphenoxyalkanecarboxylic acid derivatives of the
ormula I c~mprises reacting, in a manner known per se,
a diphenyl ether of the formula II
N02 OX . .
R ~ ~ (II)
wherein X represents hydrogen or the cation of an alkali
metal or alkaline earth metal, and R3 and R4 are as
defined in formula I, with an ~-halogenocarboxylic acid
derivative of the formula III
Hal - Cl_ A (III)
wherein A, Rl and R2 are as defined in formula I, and
: . ~, ~ ' . ,' .
, . :
- . . , - . :
~. ~
lV903~;7
-- 7 --
Hal represents a halogen atom, preferably a chlorine or
bromine atom.
The reactants of the formulae II and III are used in
about stoichiometric amounts. The reaction is carried
out advantageously in the presence of an organic solvent
which is inert to the reactants, at a temperature between
room temperature and the boiling temperature of the
reaction mixture, if appropriate, i.e. if X is hydrogen,
in the presence of an acid acceptor.
When the reaction is complete, which can take from 1 to
8 hours, the reaction product is isolated, for example by ;
distilling off the solvent and pouring the residue into
ice-water.
Suitable solvents for this reaction are in particular
organic aprotic solvents which dissolve the reactants
but do not react with them. The condensation agents are
inorganic bases, such as NaOH, KOH, NaOCH3 etc., but
also organic bases, such as tertiary amines.
The following Examples illustrate methods of manufacturing
a number of active compounds of the formula I. Further
active compounds obtained in corresponding manner are
listed in the following table.
These phenoxyphenoxyalkanecarboxylic acid derivatives of
the formula I are stable compounds which are soluble in -
conventional organic solvents, such as alcohols, ethers,
ketones, dimethyl formamide, dimethyl sulphoxide etc.
10903~7
Example 1
34,1 g (0,1 mole) of 2-nitro-4-trifluoromethyl-3'-
acetoxy-diphenyl ether are dissolved in 200 ml of acetic
acid and equimolar amounts of chlorine are introduced
into the solution at 40C with good stirring. The reaction
course is followed by gas chromatography. When the
reaction is complete, the resulting solution is poured
into ice-water and extracted with toluene/ethyl acetate
(1:1). The organic solvent is distilled off, giving an
oil which is sapnnified with 30% methanolic sodium
hydroxide solution to give the free phenol, The resulting
oil has a boiling point of 159-165C at 0.03 mm Hg.
Yield: 23,5 g,
23.5 g of 2-nitro-4-trifluoromethyl-3'-hydroxy-4'-chloro-
diphenyl ether are dissolved in 30 ml of ethyl methyl
ketone, To this solution are added 18 ml of methyl 2-
bromopropionate, 18 g of potassium carbonate and a trace
of potassium bromide on the tip of a spatula, The reaction
mixture is stirred overnight at a bath temperature of
80C, Insoluble constituents are removed by filtration
and the solvent is distilled off, The residual oil is
distilled in a high vacuum. Boiling point: 172C/
0,015 mm Hg, Yield: 20,8 g,
CH
N02 OCHCOOCH3
F3C ~ o _ ~ Cl
' : ' ~ ,-~' ' '; .... ':
-
.
, . ': ', ' ''
1(1903~7
g
Example 2
a) 68.2 g of 2-nitro-4-trimethyl-3'-acetoxy-diphenyl
ether are dissolved in 80 ml of ethylene chloride and
nitrating acid (1:1) is added dropwise at 0-5C. When
the addition is complete, the reaction mixture is stirred
for a further 1/2 hour and the reaction product is poured
into water. The precipitated product is extracted with
ethyl acetate/toluene (1:1). The solvent is distilled
off, affording a solid product which is recrystallised
from alcohol/water. Melting point: 129~-130C. Yield:
47 4 g (61.4% of theory).
b) 200 ml of methanol are added to 47.4 g of 2,4'-
dinitro-4-trifluoromethyl-3'-acetoxy-diphenyl ether and,
after addition of the equimolar amount of methanolic KOH,
the reaction mixture is allowed to stand for half an hour.
The solvent is distilled off and the residue is
dissolved in water. After acidification with 2N HCl, the
precipitated phenol is extracted with ethyl acetate/
toluene (1:1). The solvent is dis~illed off, affording
44.5 g of an oil which crystallises on standing. Melting
point: 78-79C.
c) 17.2 g of 2,4'-dinitro-4-trifluoromethyl-3'-hydroxy-
diphenyl ether are dissolved in 50 ml of 2-butanone and,
after addition of 13.4 g of methyl 2-bromopropionate,
13.8 g of potassium carbonate and a trace of potassium
iodide on the tip of a spatula, the reaction mixture is
stirred overnight at a bath temperature of 80C. The
reaction mixture is subsequently filtered and the
filtrate is concentrated. The residual oil is distilled
in a high vacu~tm. Boiling point: 217C/0.05 torr. Yield:
6.2 g of the compound of the formula
1(J903t~7
- 10 -
F3C ~ ~ N02
N02 OCH-COOCH3
CH3
R
N02 O-C-A
R4 ~ o ~ R3
- . _ .. . _ _ _ _
Rl R2 R3 R4 A . Physical
constant (~C)
. .. _ _ .. . I
CH3 H Cl CF3 COOCH3 b.p.:~72/0.015
CH3 H Cl Cl COOCH3 oil
CH3 H N02 CF3 COOCH3 b.p.:217/0.05
CH3 H Br CF3 COOCH3
CH3 H Br Cl COOCH3
CH3 H N02 Cl COOCH3 m.p. 87-88
CH3 H CN CF3 COOCH3
CH3 H N02 CF3 Cooc~l2cH=cH2
CH3 H N02 Cl COSCH3
CH3 H Cl Cl COOC2H4N(C2H5 2
CH3 H Cl CF3 CN
CH3 H Cl CF3 Cooc2H4ocH3 b.p. 200/0~001
CH3 H N02 CF3 (C2H5)2
CH3 H Cl CF3 COOCH3
~H3 H Cl CF3 COOH m;p. 168-170
CH3 H Cl Cl COOH m.p. 125
CH3 H N02 CF3 COOH r~
CH3 H Cl CF3 00~ Na ~b _ _
:. : .
. . . .
.: ', . .- ~ ' ~
. .
. . . . . . . .
. . . . . . .. .
90 3 ~ 7
. . .. . . .
Rl R2 R3 ~4 A Phys cal
._ . . __ _ . .
CH3 H Cl CN COOCH3 oil
CH3 H N02 CN COOCH3 b.p. 188/0.35
CH3 H Cl CF3 CoocH2cH=cH2 b.p. 200-230/
CH3 H Cl CF3 COSCH2CH=CH2 0.001
CH3 H Cl Cl COOC2H5 nD5 1.5705
CH3 H Cl Cl . n25 1.5596
CH3 H Cl Cl COOiC4Hg nD5 1.5604
H H N02 CF3 COOCH3 m.p. 107-108
H H N02 CF3 COOH m,p, 98-104
C2H5 HCl CF3 COOCH3
CH3 H Br CF3 COOCH3
CH3 H I CF3 COOCH3
CH3 H CN CF3 COOCH3
CH3 CH3 Cl CF3 COOC2H5
CH3 H Cl CF3 ; COSCH3 oil
CH3 H Cl CF3 COOCH2 ~ .p,:235/O,OOl
CH3 H Cl CF3 COOiC4Hg oil
CH3 H Cl CF3 COOCH2CH2Cl oil
CH3 H Cl CF3 COO-sec.C4Hg .p.:200/O,OOl
CH3 H Cl CF3 COOn-C3H7 .p.:190/O,OOl
CH3 H Cl CF3 COOCH2C_CH oil
CH3 H Cl CF3 CoocH2cHc2H5 .p.:200/O,OOl
CH3cH
CH3 H Cl CF3 COON=C ~ 3 oil
. CH3
CH3 H Cl CF3 COO ~ oil
CH3 H Cl CF3 CH3 oil
", ~ .
. . ~ .
.
1090367
- - 12
Rl R2 R3 R4 A Physical
, _ _ __ , , ,_, _ constant ( C)
CH3 H Cl CF3 COOCH2CH2N~ .
CH3 H Cl CF3 2CH2cH3
CH3 H Cl CF3 CONH .
CH3 H Cl CF3 CO ~ . .
CH3 H Cl CF3 CO- ~ . .
CH3 H Cl CF3 CoocH2cH3 .
CH3 H Cl CF3 CONOCH~ oil
CH3 H Cl CF3 COS ~ b.p.:230/O.OOl
CH3 ~ Cl CF3 COO ~ il
CH3 H Cl CF3 _ _ ~ .
.. . ...... .. ..
, ~ . - - -
.. ~.. ... ~ . :
.' ' .
.. . ...
~ , . ' .
90367
- 13
The invention also relates to herbicidal and plant
growth-regulating compositions which contain a novel
active compound of the formula I, as well as to methods
of controlling weeds by pre- and post-emergent
application and of inhibiting the growth of mono- and
dicotyledonous plants, especially grasses, cereals, soya
and tobacco shoots.
The compositions of the present invention can be in the
conventional formulations.
The compositions of the present invention are ob-
tained in known n~anner by homogeneously mixing and grinding
active substances of the general formula I with suitable
carriers, with or wi~hout the addition of dispersants or
æolvents which are ine~-t to the active substances. The
active substances can be processed to the following
formulations:
solid formulations: -
dusts, tracking powders, granules (coated granules,
impregnated granules and homogeneous granules);
active subs~ance concentrates which are dispersible in water:
wettable powders, pastes, emulsions;
liquid formulations: solutions.
The concentration of active substance in the above
described compositions is between 0.1 and 95%, preferably
between 1 and 80%. Formulations can be diluted to
c~ncentrations as low as 0.001%. The rates of application
are ordinarily from 0.1 to 10 kg, preferably from 0.25 to
5 kg, of active substance per hectare. The active
compounds of the formula I can be formulated for
e~ample as follows (parts are by weight):
- 109(~ '7
- 14
Dusts: The following subs~ance are used to prepare
a) 5% and b) 2% dust:
a) 5 parts of 2-chloro-5-~2'-nitro-4'-tri-
fluoromethyl-phenoxy)--phenoxy-propionic acid
methyl ester,
parts of talci
b) 2 parts of active substance '
1 part of highly dispersed silicic acid
97 parts of talc.
The active substances are mixed with the carriers and ground.
Granulate: The following,su~stances are used to prepare
a 5% granulate:
parts of the above active substance
0.25 part of epichlorohydrin
-0.25 part of cetyl polyglycol ether
3.25 parts of polyethylene glycol
~ 1 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. Then poly-
ethylene glycol and cetyl polyglycol ether are added. The
resulting solution is sprayed on kaolin and subsequently
evaporated in vacuo.
Wettable Po~ders
.
The following constituents are used for prepare
a) a 50%, b) a 25% and c) a 10% wettable powder: -
a) 50 parts of 2-chloro-5-(2'-nitro-4'-trifluoro-
methyl-phenoxy)-a-phenoxy-propionic acid
methyl ester,
parts of sodium dibutylnaphthylsulphonate.
3 parts of naphthalenesulphonic acid/phenolsul-
phonic acid/formaldehyde condensate (3:2:1),
parts of kaolin,
22 parts of Champagne chalk;
.: ~ :, . . ......................... . -
- - -.
1~90;~t~7
15 -
- b) 2~ parts of the above active substance,
parts of sodium oleylmethyltauride,
; 2.5 parts of naphthalenesulphonic acid/formaldehyde
condensate,
0.5 part of carboxymethyl cellulose,
parts of neutral potassium aluminium silicate,
62 parts of kaolin;
c) 10 parts of the above active substance,
3 parts of a mix~ure of the sodium salts of
saturated fatty alcohol sulphates,
parts of naphthalenesulphonic acid/formaldehyde
condensate.
82 parts of kaolin.
The indicated active substance is applied to the
- corresponding carriers (kaolin and chalk) and then these
are mixed and ground, to yield wettable powders of e~cellent
wettability and suspension power. By diluting these we~table
powders with water it is possible to obtain suspensions of
the desired concentration of active substance. Such
suspensions are used for controlling weeds and grass-like
weeds in crops of cultivated plants by the preemergent
method and for treating areas of grass.
~,
'
0 90 3 ~ 7
_ 16 -
Paste
. _
The following substances are used to manufacture a
45% paste: -
parts of 2_chloro-5-(2'-nitro-4'-trifluoro-
methyl phenox~)--phen~xy-propionic acid
methyl ester,
S parts of sodium aluminium silicate,
14 parts o cetyl polyglycol ether with 8 moles
of the ethylene oxide,
1 part of oleyl polyglycol ether with 5 moles
of the ethylene oxide,
2 parts of spindle oil,
parts of polyethylene glycol,
23 parts of water.
- The active substance is homogeneously mixed with the
adjuvants in appropriate devices and ground, yieldin~ a
paste from which, by ~ilution with water, it is possible
to obtain suspensions of the desired concentration o~
active substance. The suspensions are suitable for treating
areas of grass.
Emulsifiable Concentrate
The following ingredients are mixed to manufacture a
25% emulsifiable concentrate:
parts of 2_chloro-5-(2'-nitro-4'-trifluoro-
methyl-phenoxy)-~-phenoxy-propionic acid
methyl ester, - ~-
.
parts of a mixture of nonylphenolpolyoxy- -
ethoxy-ethylene and calcium dodecylenesul-
phonate,
3S parts of 3,5,5-trimethyl-2-cyclohexan-1-one,
parts of dimethyl formamide.
- . . ~ .. .. .
., - ~ , . -
. : - - , , .
-' 10903G7
- 17
This concentrate can be diluted with water to give emulsions
in the desired concentrations.
Instead of using the respective active substance indicated
in the foregoing formulation examples, it is also possible
to use another of the compounds comprised by the formula I.
The active substances contained in the compositions
of the present invention influence the plant growth in
different ways. Thus they inhibit, delay or prevent
primarily the growth and germination. Their action is
consequently both a pre- and post-emergent herbicidal and,
growth-inhibiting action.
Compositions of the present invention, which contain
as active component at least one compound of the formula I,
are particularly suitable for inhibiting and controlling
the growth of monocotyledonous and dicotyledonous plants,~-
such as grasses, shrubs, trees, crops of cereals and legum-
inous plants, sugar cane, tobacco plants, soya, onion and
potato tubers, ornamentals, fruit trees and vines.
The primary effect attained by the compounds of the
formula I consists in the desired reduction of the plant
size, in particular of the growth in height. In general, a
certain change in the form of the plant is allied to this
reduction in size. As a direct consequence of the reduction
of the growth in height the plant is strengthened: leaves
and stems are better developed. By shortening the distances
between internodes in monocotyledonous plants the breaking
strength is increased. In this way it is possible to prevent
to a great extent harvest losses caused by thunderstorms,
prolonged rainfall etc., which usually result in a lodging
of crops of cereals and leguminous plants, and thereby to
facilitate harvesting. As side-effect, the reduced gro~th in
height of useful plants results in a saving of fertilisers.
This also applied equally to ornamental plants and ornamental
grass plots, turf for sporting activities, grass-covered
" open spaces etc.
~.
.
, ~
90 3
- 18 -
One of the greatest problems posed by pure grass
cultivations, however, is the actual cutting of the grass
itself, whether in open spaces of urban areas, industrial
sites, playing fields, along main roads, on airport runways,
on railway embankments or the embankments of water bodies.
t In all these cases it is necessary to cut the turf or grass
periodically. This operation is not only time-consuming,
complicated and expensive in respect of labour and machinery,
but involves the personnel concerned and traffic users in
considerable hazard.
For this reason there is an urgent need in areas
with extensive traffic networks to maintain and tend the
grassy covering for strengthening road shoulders and
embankments on traffic routes on the one hand, and on the
other to keep it at a reasonable height by simple means
during the entire vegetation period. This need is fulfilled
in a very advantageous manner by applying the compounds of
the formula I.
~n analogous fashion, the labour expended on cutting
can be reduced by treating trees, shrubs and hedges,
principally in urban and industrial areas, with the compounds
of the present invention of the formula I.
The use of the active compounds of this invention
of the formula I can also advantageously influence the
growth of shoots and/or the fertility of fruit trees and
vines.
Ornamental plants o pronounced growth in length can
be reared as compact potted plants by treating them with the
active compounds of this invention.
The active compounds of the formula I are also useful -'
for inhibiting the growth of undesired suckers, for example
in tobacco and ornamental plants, thereby avoiding the labour-
consuming detaching of these suckers by hand. They are also
useful for inhibiting the formation of shoots in stored
tubers, for example those of ornamental plants, onions and
-- ~9(~3~i7
- 19 _
potatoes, and inally for increasing the yield of cultivated
plants with marked vegetative ~rowth, such as soya and sugar
cane, by accelerating the transition from the vegetative
to the generative growth phase by applying the active
compounds of the invention.
Preferably the active compounds of the formula I are
used to inhibit- the growth of grasses, cereal crops, tobacco
plants, soya and ornamental plants.
The rates of application very and depend on the time
of application. In general they are between 0.1 and 5 kg of
active substance per hectare for. preemergence application
and up to 4 kg per hectare for treating existing crops.
The facilitation of fruit abscission in the mechanical
and manual harvesting of olives and citrus fruit has become
of great ~conomic importance. Leaf abscission and defoliation
is important in the harvesting of cotton.
The active substances of the present invention develop
their action both via the parts of plants above the soil
(contact action), especially the leaves, and via the soil,
as preemergent herbicide (inhibition of germination).
The action of the compounds of the formula I as
strong growth inhibitors is evident from the fact that
most of the species of plants treated in the post-emergent
state exhibit stationary growth after a test period of
three weeks, whilst the treated parts of the plants assume
a dark green colouration. The leaves, however, do not drop.
In some plant species this growth inhibition occurs even
at a rate of application of 0.5 kg/ha and below. As not all
plant species are equally strongly inhibited in their growth,
a selective use is possible by choosing a specific low rate
of application.
The active substances of the invention are also of
interest for combination with a number of herbicides of the
phenylurea and triazine series for use in cereal crops,
maize, sugar cane, and in fruit culture and viticulture.
~ '
.: -
. .
- 1090367
:
- 20 -
In areas where there is a high risk of erosion, the
active substances of the invention can be used as growth
inhibitors in a very wide variety of crops. The weed cover
is not eliminated, but only so strongly inhibited that it
no longer competes with the cultivated plants.
In addition, the active substances of the formula I
are distinguished by a very pronounced preemergent
herbicidal action and are thus also strong germination
inhibitors.
The- following test methods were employed to establish
the usefulness of the compounds of the formula I as
herbicides (pre- and postemergen~).
Preemer~,ent herb idal action_~ermination inhibition)
In a greenhouse, imrnediately after sowing the test plants
in seed dishes the surface of the soil is treated with an
aqueous suspension of the active substances obtained from
a 25% wettable powder. Four different concentration series
were used, corresponding to 4, 2, 1 and 0.5 kg of active
substance per hectare respectively. The seed dishes are
kept in the greenhouse at 22-25C and 50 to 70% relative
humidity. The test is evaluated 3 weeks later according to
the following rating:
1 ~ plants have not germinated or are totally
w~thered
2-8 = intermediate stages of damage
9 = plants undamaged (as untreated control).
Post-emer~ent herbicidal action (Contact herbicide)
A large number (at least 7) of weeds and cultivated plants,
both mono- and dicotyledonous, were sprayed after emergence
in the 4- to 6-leaf stage with an aqueous active substance
emulsion in rates to 0.5, 1, 2 and 4 kg of active substance
per hectare and kept at 24-26C and 45-60% rela~ive humidity.
The test was evaluated, as in the preemergent test, 5 and 15
days after treatment in accordance with the same rating.
The tested compounds of the present invention had a strong
.. . . . -
.
.. ~ . ...
. .
- . : .
..
'
109 ~ 3 ~7
_ 21 -
contact herbicidal action on some plants and in many others
effected stationary growth as a symptom of the growth-
inhibiting properties.
Growth inhibition in ~rasses
Seeds of the grasses Lolium perenne, Poa pratensis, Festuca
ovina, and Dactylis glomerata were so~.~n in plastic dishes
filled with an earth/turf/sand mixture (6:3:1). The emergent
grasses were cut back weekly to a height of 4 cln above the
soil and 1 day after the last cut were sprayed with aqueous
spray mixtures of an active substance of the formula I. The
amount of active substance corresponded to a rate of appli-
cation o~ 5 kg of active substance per hectare. The growth
of the grasses was evaluated 10 and 21 days after appli-
cation.
Growth _nhibition in cereals
Spring wheat (Triticum aestivum), summer barley (Hordeum vul-
gare) and rye (Secale) was sown in sterilised soil in plastic
beakers and reared in a greenhouse. The cereal shoots were
treated 5 days after sowing with a spray broth of the active
substance. The leaf application corresponded to 6 kg of
active substance per hectare. Evaluation is made 21 days
later.
