Field of the Invention
The present invention relates to new herbicidal methods
of use for dinitroaniline compounds, in particular, the present invention relates
to herbicidal methods for dinitroaniline compounds formulated as microcapsules.
Background of the Invention
The commercial emulsifiable concentrate formulations of
certain herbicides are offen mixed with water and applied to the soll surface. Application
to a dry soll surface that remains dry for 10 to 14 days without rainfall or irrigation
may lead to a dramatic reduction in weed control. This reduced efficacy is believed
to be due to volatilization and photodegradation of the active ingredient. In addition,
recent trends in tillage methods ("no-till") result in the accretion of large amounts
of plant materials on the surface of the soll. These are mainly cellulosic materials
comprising dead stalks and leaves from the previous harvest, generally called "trash".
In no-till conditions the herbicide is applied over the trash. Certain formulations
of herbicides, notably EC formulations are absorbed by the trash. When this occurs,
a reduced amount of herbicide reaches the soll which is the intended target. As
a result the herbicide may not be present in the soll in herbicidal amounts or to
control weed growth. This absorption of herbicide is not fully released even after
Traditionally dinitroanilines that are formulated as emulsifiable
concentrates can increase phytotoxicity caused by the herbicide or by the tank mix
partners used. When dinitroanilines are applied after the crop has emerged (postemergence),
there is frequently considerable damage to the crop. EC formulations are especially
noted for crop damage post emergence.
EP0953285 discloses herbicidal mixtures comprising azafenidin
and at least one dinitroaniline herbicide selected from pendimethalin, dinitramine,
ethalfluralin, and trifluralin.
EP0380325 and US4938797 relate to the microencapsulation
of pesticides such as trifluralin.
As such, a need exists for controlling weeds in dry weather
conditions by minimizing volatilization and/or photodegradation. In addition, there
is a need for a formulation which can be applied post emergence without causing
crop damage. There is a need for formulations which are not absorbed by trash, so
as to provide better weed control.
Summary of the Invention
As embodied and broadly described herein, this invention,
in one aspect, relates to a method of inhibiting the growth of an undesired plant
by application of a herbicidally effective amount of a microcapsule composition.
The application may be pre-plant incorporated, pre-emergence, pre-transplanting
or early post-emergence. The microcapsule composition includes a dinitroaniline
compound and the microcapsule has a median diameter from about 3 micrometers to
about 10 micrometers.
In addition, the invention relates to a method of inhibiting
the growth of an undesired plant by contacting the plant with a herbicidally effective
amount of a microcapsule composition wherein the microcapsules contain a dinitroaniline
compound and the microcapsule has a wall with a thickness from about 1 % to about
In particular, the invention relates to a method for the
preemergence control of undesirable plant species comprising applying as a tank
mix to soil containing seeds of the undesirable plant a herbicidally effective amount
of a microcapsule composition comprising a dinitroaniline compound, with a herbicide
formulation comprising diflufenzopyr or dicamba or diflufenzopyr and dicamba.
Another aspect of the invention is directed to a method
for the control of undesirable plants in the presence of desirable crop plants which
comprises applying to soil containing the desirable plants and seeds of the undesirable
plant a herbicidally effective amount of a microcapsule composition comprising a
In a further aspect, the invention provides method for
safening a desirable crop from the effects of a herbicide applied to control undesirable
plants in the presence of the desirable crop plants which comprises applying a herbicidally
effective amount of a microcapsule composition comprising a dinitroaniline compound.
The method of the invention decreases the volatilization
of the active ingredient as compared to standard formulations. It also provides
for decreased photodegradation of the active ingredients. In addition, the method
of the instant invention provides for increased safety of the crop being protected
either by mitigating damage from a tank mix partner or by minimizing the effect
of the herbicide an the crop being affected. Microcapsule formulations of this invention
show a safening effect, i.e. much less damage to a variety of crops compared with
EC formulations, when applied post-emergence. Finally, microcapsule formulations
of this invention are absorbed into trash to a much smaller extent than EC formulations,
and are more effective in weed control under no-till field conditions.
Advantages of the invention will be set forth in part in
the description which follows, and in part will be obvious from the description,
or may be learned by practice of the invention. It is to be understood that both
the foregoing general description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as claimed.
The present invention may be understood more readily by
reference to the following detailed description of exemplary embodiments of the
invention and the examples included therein.
In this specification and in the claims that follow, reference
will be made to a number of terms that shall be defined to have the following meanings:
As used throughout, the term "contacting" is used to mean
at least an instance of exposure of at least one plant cell to the present composition
by applying the microcapsule composition using any method known in the art.
In general, "herbicidally effective amount" means the amount
needed to achieve an observable herbicidal effect an plant growth, including the
effects of plant necrosis, plant death, growth inhibition, reproduction inhibition,
inhibition of proliferation, and removal, destruction, or otherwise diminishing
the occurrence and activity of a plant. One of ordinary skill in the art will recognize
that the potency and, therefore, a "herbicidally effective amount," can vary for
the various compositions used in the invention.
The term "plant" as used herein means terrestrial plants
and aquatic plants. Inclusive of terrestrial plants are germinating seeds, emerging
seedlings and herbaceous vegetation including the roots and above-ground portions,
as well as established woody plants. Inclusive of aquatic plants are algae, vegetative
organisms free-floating and immersed species that are normally rooted in soil. A
non-exhaustive list of plants includes the following genera without restriction:
Abutilon, Amaranthus, Artemisia, Asclepias, Avena, Axonopus, Borreria, Brachiaria,
Brassica, Bromus, Chenopodium, Cirsium, Commelina, Convolvulus, Cynodon, Cyperus,
Digitaria, Echinochloa, Eleusine, Elymus, Equisetum, Erodium, Helianthus, Imperata,
Ipomoea, Kochia, Lolium, Malva, Oryza, Ottochloa, Panicum, Paspalum, Phalaris, Phragmites,
Polygonum, Portulaca, Pteridium, Pueraria, Rubus, Salsola, Setaria, Sida, Sinapis,
Sorghum, Triticum, Typha, Ulex, Xanthium and Zea.
Broadleaf species are exemplified without limitation by
the following: velvetleaf (Abutilon theophrasti), pigweed (Amaranthus spp.), mugwort
(Artemisia spp.), milkweed (Asclepias spp.), buttonweed (Borreria spp.), oilseed
rape, canola, indian mustard, etc. (Brassica spp.), canada thistle (Cirsium arvense),
commelina (Commelina spp.), field bindweed (Convolvulus arvensis), filaree (Erodium
spp.), sunflower (Helianthus spp.), morning glory (Ipomoea spp.), kochia (Kochia
scoparia), mallow (Malva spp.), wild buckwheat, smartweed, etc. (Polygonum spp.),
purslane (Portulaca spp.), kudzu (Pueraria spp.), russian thistle (Salsola spp.),
sida (Sida spp.), wild mustard (Sinapis arvensis) and cocklebur (Xanthium spp.).
Grass species are exemplified without limitation by the
following: wild oat (Avena fatua), carpetgrass (Axonopus spp.), brachiaria (Brachiaria
spp.), downy brome (Bromus tectorum), bermuda grass (Cynodon dactylon), yellow nutsedge
(Cyperus esculentus), purple nutsedge (C. rotundus), crabgrass (Digitaria spp.),
barnyard grass (Echinochloa crus-galli), goosegrass (Eleusine indica), quackgrass
(Elymus repens), lalang (Imperata cylindrica), annual ryegrass (Lolium multiflorum),
perennial ryegrass (Lolium perenne), rice (Oryza sativa), ottochloa (Ottochloa nodosa),
guineagrass (Panicum maximum), dallisgrass (Paspalum dilatatum), bahiagrass (Paspalum
notatum), canarygrass (Phalaris spp.), reed (Phragmites spp.), foxtail (Setaria
spp.), johnsongrass (Sorghum halepense), wheat (Triticum aestivum), cattail (Typha
spp.), and corn (Zea mays).
Other plant species are exemplified without limitation
by the following: horsetail (Equisetum spp.), bracken (Pteridium aquilinum), blackberry
(Rubus spp.) and gorse (Ulex europaeus).
The microcapsules of the present invention may be formed
by any process known in the art. U.S. Patent Nos. 5,705,174 and 5,910,314 both to
Benoff et al., describe suitable microcapsule formulations.
The microcapsules include a salt water-immiscible material
within a shell wall of a polycondensate suspended in an aqueous salt solution. One
exemplary process for making the microcapsules includes: providing an aqueous solution
containing a salt or mixture of salts and an emulsifier or mixture of emulsifiers;
dispersing, with agitation, in the aqueous solution, a salt water-immiscible solution
containing a first reactive component required to form the shell wall and the salt
water-immiscible material to form a dispersion; and adding, with agitation, to the
dispersion, a second reactive component required to form the shell wall which reacts
with the first reactive component to form the polycondensate shell wall about the
satt water-immiscible material.
The stability of the microcapsule compositions of this
invention is achieved in part through the use of a salt or mixture of salts in the
process used to prepare the compositions. The satt or mixture of salts decreases
the aqueous solubility of the material to be encapsulated and, thereby, reduces
the amount of non-encapsulated material present in the microcapsule compositions
of the present invention. This process provides microcapsule compositions which
may contain high concentrations of salt water-immiscible materials.
Salts suitable for use in the process of the present invention
include alkali metal salts such as lithium chloride, sodium chloride, potassium
chloride, lithium nitrate, sodium nitrate, potassium nitrate, lithium sulfate, sodium
sulfate, potassium sulfate, sodium monohydrogen phosphate, potassium monohydrogen
phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate and the like;
alkaline earth metal salts such as magnesium chloride, calcium chloride, magnesium
nitrate, calcium nitrate, magnesium sulfate and the like; and ammonium salts such
as ammonium chloride, ammonium sulfate, ammonium monohydrogen phosphate, ammonium
dihydrogen phosphate and the like. Preferred salts for use in this invention include
sodium chloride, potassium chloride, calcium chloride and magnesium sulfate, with
magnesium Sulfate being especially preferred.
The microcapsule compositions may be prepared using a wide
variety of emulsifiers. In particular, emulsifiers such as ethoxylated lignosulfonic
acid salts, lignosulfonic acid salts, oxidized lignins, lignin salts, salts of styrene-maleic
anhydride copolymers, salts of partial esters of styrene-maleic anhydride copolymers,
partial salts of polyacrylic acid, partial salts of polyacrylic acid terpolymers
and the like are suitable for use in the process of this invention. In the above
described emulsifiers, sodium, potassium, magnesium, calcium and ammonium salts
are generally preferred with sodium and magnesium salts being particularly preferred.
Preferred emulsifiers for use in this invention include ethoxylated lignosulfonic
acid salts, lignosulfonic acid salts and oxidized lignins, with lignosulfonic acid
salts being more preferred, and the sodium salt of lignosulfonic acid being most
The aqueous solution of the present invention preferably
contains about 5% to 30%, more preferably about 15% to 30%, by weight of the salt
or mixture of salts, depending an the type of salt. With an especially high molecular
weight salts, the weight percentage will be higher, possibly up to about 40%. With
less than 5% salt the benefits of the present invention are less apparent and with
greater than 30% (or 40%) the risk of an oversaturated solution is increased. The
aqueous solution also contains preferably about 0.5% to 5%, more preferably about
1 % to 3%, by weight of the emulsifier or mixture of emulsifiers.
The present application pertains, in particular, to microcapsules
that include at least one dinitroaniline compound. Exemplary dinitroaniline compounds
include pendimethalin, trifluralin, ethalfluralin, butralin and benfluralin. The
microcapsule compositions of the present invention preferably include about 5% to
60%, more preferably about 20% to 50%, by weight of the dinitroaniline compound.
The salt water-immiscible solution is prepared by mixing
the first reactive wall forming component with the dinitroaniline compound at a
temperature above the melting point of the dinitroaniline compound. Alternatively,
the salt water-immiscible solution may be prepared by mixing the first reactive
wall forming component with a solution of the dinitroaniline compound in a suitable
salt water-immiscible solvent.
Salt water-immiscible solvents which are suitable for use
include solvents which do not react undesirably with any of the ingredients used
in the invention process. Suitable solvents include salt water-immiscible hydrocarbons,
aromatic hydrocarbons, chlorinated hydrocarbons, chlorinated aromatic hydrocarbons,
ketones, long chain esters and mixtures thereof.
The polycondensate shell wall of the present invention
may be any known shell wall material and is preferably a polyurea, a polyurethane,
a polyamide, a polycarbonate or a polysulfonamide, with a polyurea shell wall being
especially preferred. The polycondensate shell wall may be prepared from reactive
components which are well known in the art. Preferably, the polycondensate shell
wall is prepared by reacting a first reactive component selected from the group
consisting of a polyisocyanate, a polyacid chloride, a polychloroformate and a polysulfonyl
chloride with a complementary second reactive component selected from the group
consisting of a polyamine and polyol to form the appropriate polycondensate shell
wall. In a preferred process of the present invention, a polyisocyanate is reacted
with a polyamine to form a polyurea shell wall.
Polyisocyanates which are suitable for use include di-
and triisocyanates wherein the isocyanate groups are attached to an aliphatic or
aromatic group. Suitable polyisocyanates include tetramethylene diisocyanate, pentamethylene
diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethene-4,4'-diisocyanate,
polymethylene polyphenylene isocyanate, 2,4,4'-diphenyl ether triisocyanate, 3,3'-dimethyl-4,4'-diphenyl
diisocyanate, 3,3'-dimethoxy-4,4'-diphenyl diisocyanate, 1,5-naphthylene diisocyanate,
4,4'4"-triphenylmethane triisocyanate, the reaction product of tetramethylxylene
diisocyanate and trimethylol propane, and the like with polymethylene polyphenylene
isocyanate being preferred.
Polyamines suitable for use in the process of the present
invention include ethylenediamine, propylene-1,3-diamine, tetramethylenediamine,
pentamethylenediamine, 1,6-hexamethylenediamine, diethylenetriamine, triethylenetetramine,
tetraethylenepentamine, pentaethylenehexamine, 4,9-dioxadodecane-1, 12-diamine,
1,3-phenylenediamine, 2,4- and 2,6-toluenediamine, 4,4'-diaminodiphenylmethane and
the like with 1,6-hexamethylenediamine being preferred. Hydrochloride salts of those
polyamines may also be used in the process of the present invention.
The satt water-immiscible solution preferably contains
about 1% to 15%, more preferably about 2% to 8%, by weight of the first reactive
wall forming component. The second reactive wall forming component is preferably
present in an amount of about 0.3% to 5%, more preferably about 0.6% to 3%, by weight
relative to that of the salt water-immiscible solution.
Various shell wall thicknesses may be utilized in the present
invention. In particular, for use with dinitroaniline compounds, the preferred wall
thickness is from about 1% to about 10%. Even more preferably, the wall thickness
is from about 2% to about 5%. This amount is defined as the sum of the first reactive
wall forming component amount plus the second wall forming amount divided by the
sum of the dinitroaniline compound amount plus the first and second reactive wall
forming component amounts times 100.
The process of making the microcapsules is generally conducted
at an elevated temperature to increase the solubility of the salt, to maintain the
salt water-immiscible material in a liquid state, and to enhance the wall forming
reaction rate. This process is preferably conducted at a temperature of about 35°C
to 85°C and is more preferably conducted at a temperature of about 50°C
The microcapsules prepared by the process of this invention
preferably have a median diameter of about 3 micrometers to 50 micrometers and more
preferably about 3 micrometers to 10 micrometers.
Other optional ingredients include agronomically acceptable
inert solid or liquid carriers, anti-settling agents, salts, antifoams, surfactants,
pH-adjusters, anti-freeze agents and the like may be added to the microcapsule compositions.
In particular, the present invention provides concentrated
microcapsule herbicidal compositions which comprise about 10% to 70%, preferably
about 30% to 50%, by weight of a dinitroaniline compound; about 30% to 90%, preferably
about 50% to 70%, by weight of an aqueous solution which contains about 0.01 % to
0.05% by weight of a anti-settling agent, and up to about 0.5% by weight of an antifoam.
If desired, the microcapsules may be separated out of the
microcapsule compositions prepared by the process of the present invention by methods
known in the art such as filtration or spray drying to obtain storage-stable flowable
When operating in accordance with the present invention,
the growth of an undesired plant may inhibited or controlled by contacting the plant
with a herbicidally effective amount of the composition of the present invention.
The application of such herbicidal compositions to terrestrial plants can be carried
out by conventional methods, e.g. boom and hand sprayers and aerial sprayers. The
compositions can also be applied from airplanes as an aerial spray because of their
effectiveness at low dosages.
The application of a herbicidally effective amount of the
compositions of this invention to the target plant is dependent upon the response
desired in the plant as well as such other factors as the plant species and stage
of development thereof and the amount of rainfall. In foliar treatment for the control
of terrestrial plants, the active ingredients are desirably applied in amounts from
about 1,12·10-4 (0.01) to about 22,42·10-2 (20)
or more kg per are (pounds per acre). In applications for the control of aquatic
plants, the active ingredients are desirably applied in amounts of from about 0.01
parts per million to about 1000 parts per million, based on the aquatic medium.
The compounds of the present compositions may be readily synthesized using techniques
generally known to synthetic organic chemists.
The following examples are put forth so as to provide those
of ordinary skill in the art with a complete disclosure and description of how the
components, compositions, articles, devices, and/or methods claimed herein are made
and evaluated, and are intended to be purely exemplary of the invention and are
not intended to limit the scope of what the inventors regard as their invention.
Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts,
temperature, etc.) but some errors and deviations should be accounted for. Unless
indicated otherwise, percent is percent by weight given the component and the total
weight of the composition, temperature is in °C or is at ambient temperature,
and pressure is at or near atmospheric. Emulsifiable concentrates, known formulations,
are identified as "EC". Formulations of the invention are identified as "CS".
Pendimethalin CS and Trifluralin CS were prepared essentially
according to the procedure set forth in US patent 5705174. The formulation contained
the following components where the figures are % w/w of each component:
Reax 88B 15% solution
Diwatex 200 15%solution
THIND 30 AF antifoam
Mondur MRS poly phenyl
Kelzan S 2% solution
Two trays were prepared with soil containing 3.2% organic
material, pH of 4.8, cation exchange capacity (CEC) (meq/100gms) of 25.2, 20% sand,
60% silt, and 20% clay, silt loam. The two trays were treated with pendimethalin,
at a rate of 1,12·10-2 kg/are (1.0 lb per acre) of the active ingredient
and 1,87 𝓁 of carrier per are (20 gallons of carrier per acre)- one tray
with pendimethalin CS (4% wall thickness) and one tray with pendimethalin EC. Crabgrass
(digitaria spp.) seed was uniformly spread over each tray and covered with a very
thin layer of soil prior to treating. The trays were not watered for 14 days. Six
weeks after treatment, the tray treated with pendimethalin CS had 95% crabgrass
control and the tray treated with pendimethalin EC had 70% crabgrass control. This
example illustrates the volatilization of the EC formulation and the relative stability
of the microcapsule formulation on the soil surface. The residual amount of herbicide
is greater for the microcapsules and has a greater herbicidal effect than the EC
Diluted formulations of Pendimethalin CS (4% wall thickness,
capsule diameter 7.0 microns) and Pendimethalin EC and Trifluralin CS (3.1% wall
thickness, capsule diameter 10.0 microns) and Trifluralin EC were applied to glass
fiber filter papers and placed in an oven in forced draft at 45°C. At intervals
of days, the papers were removed and the residual active ingredient assayed as shown
in Table 1 where it can be seen that the microcapsule formulations of dinitroanilines
of this invention lose less herbicide by volatilization than the EC formulations.
Table 1: Results of Volatilization Testing
of Active Ingredient Remaining
Pendimethalin CS (4% wall thickness, microcapsule size
= 7.0 microns, median diameter) and pendimethalin EC formulations were applied to
segregated corn trash (leaf, stalk, pith) dropwise and allowed to absorb for 15
minutes. Then the pieces of trash were placed in water and shaken until all removable
pendimethalin was rinsed out. The concentration of pendimethalin in the rinsate
was then assayed, as a percentage of the amount added. The results are set forth
in Table 2 and show that the amounts of pendimethalin removable from corn trash
are greater when formulated as microcapsules of the invention.
Table 2: Results of Availability Testing
of Removable Pendimethalin
A mixed grass/alfalfa field contained 10,16 cm (4-inch)
alfalfa, 10,16 cm (4-inch) Orchard grass and 6,35 cm (2.5-inch) reed canary grass.
Pendimethalin CS and Pendimethalin EC were applied to separate portions of the field.
One month after the application, a 3,05 m (ten-foot) by 0,762 m (2.5-foot) section
of each plot was cut with a sickle bar mower and the alfalfa and grass component
were separated and weighed. The results are set forth in Table 3 where it can be
seen that at higher application rates The microcapsule formulation increases the
desirable alfalfa yield relative to the EC formulation.
Table 3: Results of Safety Testing-Alfalfa
Rate kg ai/are
% Grass reduction
In a greenhouse test, lettuce seeds (Waldmann's Dark Green
M.I.) were planted and treated with pendimethalin EC or pendimethalin CS at the
rate of 8,41·10-3 kg ai/are (0.75 lb al/A). The germinated lettuce
was observed at 11 and 14 days after treatment. In both cases the microcapsule formulation
caused less damage to lettuce than the EC formulation. The results are set forth
in Table 4.
Table 4: Results of Safety Testing-Lettuce Preemergent
Days after Treatment
Days after Treatment
In a greenhouse test, lettuce plants (Waldmann's Dark Green
M.I.) at the 2-4 leaf stage of growth were treated with pendimethalin EC or pendimethalin
CS at the rates of 8,41·10-3 (0.75) and 16,81·10-3
kg ai/are (1.5 lb al/A). The lettuce was observed at 7 and 14 days after treatment
At both application rates the microcapsule formulation caused less damage to lettuce
than the EC formulation. The results are set forth in Table 5.
Table 5: Results of Safety Testing-Lettuce Post emergent
Days after Treatment
Days after Treatment
kg ai/are (0.75 lb ai/A)
kg ai/are (0.75 lb ai/A)
kg ai/are (1.5 lb ai/A)
ai/are (1.5 lb ai/A)
In a greenhouse test, tomato plants (Celebrity) 5-6" were
treated with pendimethalin EC or pendimethalin CS at the rates of 8,41·10-3
and 16,81·10-3 kg ai/are (0.75 and 1.5 lb ai/A). The tomato 14 plants
were observed at 8 and 11 days after treatment. At both application rates the microcapsule
formulation caused less damage to tomatoes than the EC formulation. The results
are set forth in Table 6.
Table 6: Results of Safety Testing-Tomato Post emergent
Days after Treatment
Days after Treatment
kg ai/are (0.75 lb ai/A)
kg ai/are (0.75 lb ai/A)
kg ai/are (1.5 lb ai/A)
kg ai/are (1.5 lb ai/A)
Distinct® herbicide, a mixture of diflufenzopyr
and dicamba-sodium, was tank-mixed with pendimethalin CS and pendimethalin EC and
applied to V3 and V6 stage of corn. The treatments were as follows:
kg/are (12 oz/acre) and Pendimethalin EC
l/are (115 fl oz/acre)
kg/are (12 oz/acre) and Pendimethalin CS
l/are (100 fl oz/acre)
kg/are (12 oz/acre)
kg/are (8 oz/acre) and Pendimethalin EC
l/are (218 fl oz/acre)
kg/are (8 oz/acre) and Pendimethalin CS
l/are (183 fl oz/acre)
kg/are (8 oz/acre)
The plants were rated at 7 days after treatment and post
tassel. The results are set forth in Table 7 and show that the microcapsule CS composition
caused less damage to the corn than the EC formulation.
Table 7: Results of Safety Testing-Tank-mix Combination
% Lean 7 DAT V3
% Lean 7 DAT V6
% Leaf Fusing Post