LIQUID HERBICIDAL COMPOSITION HAVING EXTENDED PENETRATING AND SYSTEMIC ACTIVITY

HERBICIDE LIQUIDE A PENETRATION ET ACTIVITE SYSTEMIQUE TEMPORISEES

English Abstract

LIQUID HERBICIDAL COMPOSITION HAVING
EXTENDED PENETRATING AND SYSTEMIC ACTIVITY
Abstract of the Disclosure
A liquid herbicidal composition is dis-
closed which retains its penetrating and systemic
activity after application to susceptible flora under
normal ambient conditions for a period of at least
six hours by combining at least two different salts
of at least one herbicidally active compound and a
polyhydric alcohol. The salts are preferably amine,
ammonium or alkali metal salts of herbicidally active
acidic compounds which are halogenated carboxylic
acids, aromatic carboxylic acids and the halogenated
aromatic carboxylic acids and particularly deriva-
tives of phenoxy acids or benzoic acids, organic
arsenic acids as well as halogenated aliphatic car-
boxylic acids. The polyhydric alcohol is preferably
a polyhydric diol having 2 to 6 carbon atoms or
glycerol. Chelating and dispersing agents may also
be included in the formulation. The herbicidal
composition upon application to noxious vegetation
has the unexpected property of retaining its phyto-
toxic activity throughout the maximum residence time
necessary for effective weed and brush control by
virtue of the fact that the composition not only
resists crystallization but also displays no tendency
throughout such maximum exposure time to either burn
or otherwise damage the external cellular layers of
the plant being treated which would impede active
agent penetration into the plant, or reversion to
acid form that could produce outer cellular layer
burn or scaling with the same detrimental effect on
penetration of the herbicide and systemic activity.

Claims

The embodiments of the invention in which an
exclusive right or privilege is claimed are defined as
follows:
1. An aqueous liquid herbicidal composition
especially adapted for aircraft application while
retaining the properties of extended penetrating and
systemic activity comprising:
a liquid eutectic mixture consisting essentially
of at least two different salts of at least one
herbicidially active compound, said salts having
a stable pH of no less than about 6 and being
selected from the group consisting of
methylamine, ethylamine, isopropylamine,
monomethanolamine, monoethanolamine,
monoisopropanolamine, dimethylamine,
diethylamine, diisopropylamine, dimethanolamine,
diethanolamine, diisopropanolamine,
trimethylamine, triethylamine, triisopropylamine,
trimethanolamine, triethanolamine,
triisopropanolamine, ammonium, sodium, potassium,
and lithium salts of herbicidally active acidic
compounds selected from the group consisting of
2,4-dichlorophenoxyacetic acid,
2,4-dichlorophenoxypropionic acid,
2,4-dichlorophenoxybutyric acid,
2-methyl-4-chlorophenoxyacetic acid,
2-methyl-4-chlorophenoxypropionic acid,
2-methyl-4-chlorophenoxybutyric acid,
2,4,5-trichlorophenoxy acetic acid,
2,3,6-trichlorobenzoic acid,
2-methoxy-3,6-dichlorobenzoic acid,
2-methoxy-3,5,6-trichlorobenzoic acid,
4-chloro-2-oxobenzothiazolin-3-ylacetic acid,
4-amino-3,5,6-trichloropicolinic acid,
trichloroacetic acid, 2,2-dichloropropionic acid,
13

3-amino-2,5-dichlorobenzoic acid, methane arsonic
acid, 2,3,6-trichlorophenylacetic acid and
3,6-endoxohexahydro phthalic acid; and
a sufficient quantity of a polyhydric alcohol selected
from the group consisting of polyhydric diols
having from 2 to 6 carbon atoms and glycerine
which is capable of causing the liquid herbicidal
composition to remain noncrystalline and exhibit
a pH of no less than about 6 under normal ambient
conditions following application to susceptible
flora for a period of at least six hours.
2. A liquid herbicidal composition as set forth
in Claim 1, wherein said polyhydric alcohol is selected
from the group consisting of ethylene glycol, propylene
glycol, isopropylene glycol, glycerine, 2,3-hexane diol,
2-methyl-2,4-pentane diol, 1,2-pentane diol, 1,6-hexane
diol and 2-methyl-1,2 butane diol.
3. A liquid herbicidal composition as set forth
in Claim 1, wherein is included a chelating agent.
4. A liquid herbicidal composition as set forth
in Claim 1, wherein is included a dispersing agent.
5. A liquid herbicidal composition as set forth
in Claim 1, wherein said mixture includes a quantity of
water.
6. A liquid herbicidal composition as set forth
in Claim 1, wherein is provided from 10 to 90 parts by
weight of one of said salts and from 10 to 90 parts by
weight of a second different salt of said herbicidally
active compound.
7. A liquid herbicidal composition as set forth
in Claim 1, wherein said herbicidally active compound is
2,4-dichlorophenoxyacetic acid.
8. A liquid herbicidal composition as set forth
in Claim 7, wherein one of said salts is the dimethylamine
alt of 2,4-dichlorophenoxyacetic acid.
14

9. A liquid herbicidal composition as set forth
in Claim 8, wherein is the diethanolamine salt of
2,4-dichlorophenoxyacetic acid.
10. A liquid herbicidal composition as set forth
in Claim 3, wherein said chelating agent is citric acid.
11. A liquid herbicidal composition as set forth
in Claim 4, wherein said dispersing agent is a substituted
phenyl propane ligno-sulfonate.
12. A liquid herbicidal composition having
extended penetrating and systemic activity comprising the
mixture of the dimethylamine and diethanolamine salts of
2,4-dichlorophenoxyacetic acid and a sufficient quantity
of ethylene glycol to cause the liquid herbicidal
composition to remain noncrystalline under normal ambient
conditions for a period of at least six hours.
13. A liquid herbicidal composition having
extended penetrating and systemic activity comprising the
mixture of on a parts by weight basis of 3.9 parts of
2,4-dichlorophenoxyacetic acid, 1.7 parts of dimethylamine
(40%), .5 part of diethanolamine (98%), .2 part of citric
acid, .02 part of a substituted phenyl propane
ligno-sulfonate, 1 part of ethylene glycol, and 2.6 parts
of water.
14. A method of controlling noxious vegetation
comprising the steps of:
applying to said vegetation by aircraft an effective
amount of a liquid eutectic mixture consisting
essentially of at least two different salts of at
least one herbicidally active compound, said
salts having a stable pH of no less than about 6
and being selected from the group consisting of
methylamine, ethylamine, isopropylamine,
monomethanolamine, monoethanolamine,
monoisopropanolamine, dimethylamine,
diethylamine, diisopropylamine, dimethanolamine,

diethanolamine, diisopropanolamine,
trimethylamine, triethylamine, triisopropylamine,
trimethanolamine, triethanolamine,
triisopropanolamine, ammonium, sodium, potassium,
and lithium salts of herbicidally active acidic
compounds selected from the group consisting of
2,4-dichlorophenoxyacetic acid,
2,4-dichlorophenoxypropionic acid,
2,4-dichlorophenoxybutyric acid,
2-methyl-4-chlorophenoxyacetic acid,
2-methyl-4-chlorophenoxypropionic acid,
2-methyl-4-chlorophenoxybutyric acid,
2,4,5-trichlorophenoxyacetic acid,
2,3,6-trichlorohenzoic acid,
2-methoxy-3,6-dichlorobenzoic acid,
2-methoxy-3,5,6-trichlorobenzoic acid,
4-chloro-2-oxobenzothiazolin-3-ylacetic acid,
4-amino-3,5,6-trichloropicolinic acid,
trichloroacetic acid, 2,2-dichloropropionic acid,
3-amino-2,5-dichlorobenzoic acid, methane arsonic
acid, 2,3,6-trichlorophenylacetic acid and
3,6-endoxohexahydrophthalic acid, and
a sufficient quantity of a polyhydric alcohol selected
from the group consisting of polyhdric diols
having from 2 to 6 carbon atoms and glycerine
which is capable of causing the liquid herbicidal
composition to remain noncrystalline and exhibit
of pH of no less than about 6 under normal
ambient conditions following application to
susceptible flora for a period of at least six
hours.
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Description

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1 LIQUID HERBICIDAL COMPOSITION HAVIMG
EXTENDED PENETRATING AND SYSTEMIC ACTIVITY
Background of the Invention
l. Field of the Invention
. ~
This invention relates to herbicidal compo-
sitions in liquid form having extended penetrating
and systemic activity upon application to susceptible
flora. The phytotoxic agent is resistant to initial
plant outer cell layer burn that would interfere with
its activity but also has been found to be free of
such cell damage properties during the extended
period of exposure of the plant to the active agent
which is a major feature of its total efficacy since
the product also resists crystallization for an
extended period under normal ambient conditions after
applicationO These desirable characteristics are
realized in part because the pH of the material is at
least 6 or above at the time of application and
remains at such level long periods of time involving
many days thus preventing reversion of the toxicant
to an acid form which could adversely affect the
surface cellular structure of the plants and thus
impede the permeation of the material into the plants
as well as translocation thereof to the root system.
2. Description of the Prior Art
Acidic herbicides such as 2,~-dichloro-
phenoxyacetic acid have long been used to control
unwanted vegetation. 2,4-D as it is generally known
is an insoluble crystalline material having a pH of
approximately 2. For convenient application, it is
normally converted to liquid form by conversion to
water soluble salts or emulsified esters. The ester
formulations have been found to be more effective
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l than the salts in the control of noxious vegetation
but have the unwanted characteristic of migrating to
adjacent desirable vegetation because of the volatil-
ity thereof with unacceptable resultant damage.
Efforts to solve the volatility problem
including preparation of water soluble salts such as
the dimethylamine salt of 2,4-D have not been totally
satisfactory because upon volatilization of the amine
the herbicide reverts back to its initial acidic
form. The acidic composition on the plant surface
damages the plant cells thus forming a ~echanical
barrier o~ dead tissue which prevents effective
penetra~ion of the herbicide into the plant and
translocation to all of the above ground and below
ground segments.
Canadian Patent No. 879,602 of Ciba-Geigy
Canada Ltdo dated August 31, 1971 describes relative-
ly non-volatile herbicidal compositions produced by
reacting amines, ammonium, sodium, potassium and
lithium compounds with acidic compounds containing
for example acid moieties preferably comprising
halogenated carboxylic acids, aromatic carboxylic
acidsJ and the halogenated aromatic carboxylic acids,
with particularly preferred groups being derivatives
of phenoxy acids, and derivatives of benzoic acids.
Other groups of compounds are defined as including
organo arsenic acids, as well as halogenated ali-
phatic carboxylic acids. In its preferred embodi-
ments, the compositions of the Canadian Patent in-
volve ~he mixture of two or more different salts
containing the different salts in varying propor-
tions. One or more surfactants are described as
being added to the composition causing the liquid to
be relatively non-volatile at normal ambient tempera-
ture conditions.
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l Although the formulations of the referenced
Canadian '602 Patent did exhibit the desired low
volatility, the pH of the herbicidal compositions was
sufficiently on the acid side to cause the material
to in effect burn the surface layers of the plants on
which the herbicide was applied thereby creating a
barrier to phytotoxic activity of the herbicide and
limiting its effectiveness over desired extended
periods of time. As a consequence, the compositions
disclosed in the '602 Canadian Patent, although in
commercial use, do not lend themselves to use in many
aerial applications where extended activity under
varying ambient conditions is an essential property
of the composition and suffer from the defect of
causing plant burn in many instances which signifi-
cantly reduces its activity in a relatively short
period of time after application.
A herbicidal composition especially de-
signed for agricultural spraying is described in Guth
Patent No. 3,764,293 of October 9, 1973 wherein the
patentee suggests that acidic herbicidal agents
reacted with metal hydroxides to produce salts are
combined with polyhydric diols to assist in dispers-
ion of the herbicidal material in the base water.
Here again, the formulation although clearly capable
of exhibitin~ initial herbicidal activity had the
tendency to burn the surface cellular structure of
susceptible plants which limited activity of the
material over extended periods of time and required
more frequent application of the phytotoxic agent
than is desirable.
Summary of the Invention
The present invention solves the problems
inherent in herbicidal compositions of the prior art
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1 by providing an improved formulation prepared fro~
acidic herbicides which can be applied to unwanted
vegetation in a physical and chemical form such that
the solubilizing agents do not undergo chemical
change or volatilize to an extent that the salt can
revert bac~ to lts acidic form in a relatively short
period of time. Instead, a relatively non-acidic
herbicidal composition has now been discovered which
can be deposited on susceptible flora in a relatively
viscous form which is resistant to reversion back to
acidic form. The resulting viscous droplets may
reside upon the plant surface without damage to the
tissue and is able to penetrate for an extended
period of time and translocate to all parts of the
plant.
The preferred formulation consists of the
dimethylamine and diethanolamine salts of 2,4-D
having a pH above 6~0 along with a sufficient quant-
ity of ethylene glycol to cause the liquid herbicidal
composition to remain non-crystalline at a pH no less
than about 6.0 under normal ambient conditions fol-
lowing application to susceptible flora for a period
of at least about six hours. Citric acid as a che-
lating agent as well as a ligno-sulfonate type dis-
persing a~ent may also be included in the formulationalong witll an adequate quantity of water to provide a
composition of desired viscosity for a particular
application.
Preferred formulations having the general
characteristics described applied to unwanted vegeta-
tion in tolerant crops or in fallow land have been
found to exhibit increased herbicidal efficacy over
extended periods of time. Deep rooted perennial
weeds such as bindweed and leafy spurge normally
fully recover and regrow from applications of 2,4-D.
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1 However, compositions of the present invention have
demonstratably better regrowth inhibition and eventu-
ally completely destroy the plants. Data taken from
field trials in which ~ild Mustard, Lamb's Quarter~s,
Stinkweed, Smartweed, Canada Thistle, Wild Buckwheat,
Cowcockle, Volunteer Rape, Tansy Mustard, Hempnettle,
Prostrate Pigweed, and Redroot pigweed were present
resulted in improved control.
A further advantage exhibited by composi-
tion's of this invention is an increase in the amountof deposition of a herbicide in a target area using
ultra low volumes from aircraft applications compared
to conventional ~ethods of applying si~ilar compounds
in usual amounts of water. The normal aircraft
application of pesticides occurs under warm dry
conditions and the resulting environmental influence
produces very small droplets which move from the
target area on air currents. The preferred embodi-
ment of the invention results in drops with higher
surface tension and a viscosity which combine to
result in droplets which resist breakup between
discharge from the spray nozzle and the target area.
The larger droplets which are airborne for a lesser
period of time have a greater propensity to fall
within the area of the target than with previous
formulations.
Description of the Preferred Embodiment
The preferred liquid herbicidal composition
is made by preparing a liquid mixture of at least two
different salts of at least one herbicidally active
compound, said salts having a stable pH of no less
than about 6.0 being selected from the group consist-
ing of methylamine, ethylamine, isopropylamine, mono-
methanolamine, monoethanolamine, monoisopropanol-

~2'.~g~
1 amine, dimethylamine, diethylamine, diisopropylamine,dimethanolamine, diethanolamine, diisopropanolamine,
trimethylamine, triethylamine, triisopropylamine,
trimethanolamine, triethanolamine, triisopropanol-
amine, ammonium, sodium, potassium, and lithium saltsof herbicidally active acidic compounds selected from
the group consisting of 2,4-dichlorophenoxyacetic
acid, 2,4-dichlorophenoxypropionic acid, 2,4-dichlor-
ophenoxybutyric acid, 2-methyl-4-chlorophenoxyacetic
acid, 2-methyl-4-chlorophenoxypropionic acid, 2-
methyl-4-chlorophenoxybutyric acid, 2,4,5-trichloro-
phenoxyacetic acid, 2,3,6-trichlorobenzoic acid, 2
methoxy-3, 6-~ichlorob~nzoic acid, 2-methoxy-3, 5, 6-
trichlorobenzoic acid, 4-chloro-2-oxobenzothiazolin-
3-ylacetic acid, 4-amino-3,5,6-trichloropicolinic
acid, trichloroacetic acid, 2,2-dichloropropionic
acid, 3-amino-2,5-dichlorobenzoic acid, methane
arsonic acid, 2,3,6-trichlorophenylacetic acid and
3,6-endoxohexahydrophthalic acld. A sufficien~
quantity of polyhydric alcohol is also included in
the composition to cause the product to have eutectic
characteristics and thereby remain non-crystalline
and at a pH of no less than about 6.0 under normal
ambient conditions following application to suscept-
ible flora for a period of at least six hours. Thepreferred eutectic formulation is prepared by use of
a polyhydric diol having 2 to 6 carbon atoms or
glycerol with best results being obtained when a
glycol such as ethylene glycol, 2,3-hexane diol, 2-
methyl-2,4-pentane diol, l,6-hexane diol and 2-
methyl-l,2 butane diol or glycerine is employed.
Chelating agents may be added such as
citric acid, lactic acid or ethylenediaminetetra-
acetic acid to stabilize the composition, particul-
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1 arly where water is added as a diluent that maycontain various metal or salts of metals.
Dispersing or wetting agents such as a
substituted phenyl propane ligno-sulfonates may be
added.
A polar solvent such as water may be added
to adjus~ the concentration of the preferred formula-
tion for maximum economic and biological benefit.
The concentrations of salts may vary from
10 to 90 parts by weight of one of the salts and from
10 to 90 parts by weight of a second different salt
of the herbicidally active compound with preferred
formulations usually being in the range of about 1
part of one salt to about 2 parts of the other salt.
A particularly preferred composition in-
cludes on a parts by weight basis of 3.9 parts of
2,4-dichlorophenoxyacetic acid, 1.7 parts of di-
methylamine (40%), 0.5 part of diethanolamine (98%),
.2 part of citric acid, .02 part of a substituted
phenyl propane ligno-sulfonate, 1 part of ethylene
glycol, and 2.6 parts of water. The pH of this
composition varies from about 7.6 to about 8Ø
Typical tests as recorded herein have demonstrated
~hat this formulation when applied and exposed to
ambient conditions will retain a pH exceeding 6.5 for
periods up to 20 days.
A specific embodiment of the best mode of
this invention is as follows:
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_ngredient Parts by Weight
Tech. 2,4-D Acid (98%) 3.9021
Dimethylamine (40%) 1.6586
Diethanolamine (98~o) 0.5292
Citric Acid 0.2100
Marasperse CB* O 0178
Ethylene Glycol 1 0000
Water 2 5742
*Substituted phenyl propane ligno-s;llfonate -- carbon
black dispersion.
A composition of Formula I above was com-
pared with a typical formulation of Canadian Patent
No. 879,602 (hereinafter exemplified by Formula II)
and a standard commercial formulatio~ of 2,4-D typic-
ally used in agriculture and commerce (hereinafterexemplified by Formula III). Formula II (Code EH712-3)
__ _ _ _ . _
In~redients Part _by Weight
Tech. 2,4-D Acid (98%) 4.2133
Dimethylamine (40%) 1.7736
Diethanolamine (98%) 1.0075
Igepal CA-630~ 0 4163
Citric Acid 0 2082
Water 2.3481
*An alkylphenoxypoly (oxyethylene) ethanol
Formula III (Code 814)
. .
Ingredients Parts by Weight
Dimethylamine Salt of
2,4-D Acid (98%)* 46.4
Inert Ingredients 53.6
*3.8 parts by weight of 2,4-D acid per gallon (isomer
specified in accordance with AOAC Method No. 6 D01-5)

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1 Field tests utilizing Formula I compared
with Formula III were conducted on the following
species:
Flora Abbrevia~ion
Lamb's Quarters LQ
Stinkweed SW
Smartweed SMW
Canada Thistle CT
Wild Buckwheat WB
Cowcockle CC
Volunteer Rape VR
Prostrate Pigweed PPW
Redroot Pigweed RRPW
LOCATION: 1
WEED CONTROL RATING
Formula Rate/A VR S~ CT WB LQ
Crop: Wheat
I 6.6 oz. 6 6 6 6 8
III 6 oz. 5 5 4 5 7
Untreated 0 0 0 0 0
Crop: Oats, Barley
I 6.6 oz. 9 6 5 5 7
III 6 oz. 8 5 5 4 7
Untreated 0 0 0 0 O
LOCATION: 2
Crop: Barlev
_
Formula Rate/A CT WB LO RRPW
I 8 oZ. 7 7 7 8
III 8 oz. 5 5 7 7
30Untreated 0 0 0 O

LOCATION: 3
Croe: Oats, Barley
Formula Rate/A LQ RRPW SW WB VR CT
I 8 oz. 9 9 9 5.5 8 8
III 8 oz. 7 7 G S 7 7
Untreated 0 0 0 0 0 0
LOCATION: 4
Crop- Wheat
Formula Rate/A LQ SW RRPW PPW WB CC
I 8 oz. 9 8 ~ 7 6 5
III 8 oz. 8 7 7 6 5 5
Untreated 0 0 0 0 0 0
In all of the four locations in all of the
crop species the rating for all treatments for crop
tolerance was 9 representing no injury from any of
the applications.
In field evaluations in the control of hard
to l~ill, deep rooted perennial weeds applications
were made to stands of leafy spurge, Canada Thistle
and field bindweed (perennial morning glory). Field
data are presented in the following tables:
L fy Spurge
Average No. of Stems Per Plant
Formula Rate 19801981~ 1982
I 4 lb/A 73.67 7
Untreated 63.6770.333.0
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l Canada Thistle
Average ~o. ot Stems Per Sq. Yd.
Formula ~ate 1980 1981 1982 1983
1 4 lb/A 176 12 2 1.2
Untreated 212 213 212 213
Field Bind Weed
Average No. of Stems Per Sq. Yd.
Formula Rate 1 _ 1 _ 1982
I 3 lb/A 11 3
Un~reated 10 14 9
Studies to evaluate the pH of Formulas I,
II and III above after the material had beel1 allowed
to stand on glass plates under the same ambient
conditions for a period of 20 day.
pH
Formula Initial Final
I 7.7 6.5
II 7.5 5.0
III 8.3 5.3
Leaves from several species of plants were
excised and removed to a laboratory where measured
droplets of Formulas I, II and III were applied.
Observations were made at intervals during a three-
day period. Necrotic areas appeared under all of the
droplets from Formulas II and III under certain
species in a matter of hours and in the others at
least by the end of the three-day observation period,
but not under the droplets of Formula I. This obser-
vation confirms that Formulas II and III sufficiently
damaged the epithelial and palisade cells of the
plants to an extent that penetration of the herbicide
would have been sufficiently inhibited to adversely
affect the systemic activity of the composi~ion.
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1 These findings relate directly to and explain the
efficacy of Formula I as compared with Formula III
recorded in the tables above.
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