FIELD OF THE INVENTION
The present invention relates to herbicidal colnpositions comprising, a)
Imazethapyr and b) another herbicidal active selected from a group of
triazolinone herbicides comprising bencarbazone, carfentrazone and
sulfentrazone.
BACKGROUND OF THE INVENTION
The following discussion of the prior art is provided to place the invention in an
appropriate technical context and enable the advantages of it to be more fully
understood. It should be appreciated, however, that any discussion of the prior art
throughout the specification should not be considered as an express or implied
admission that such prior art is widely known or forms part of common general
knowledge in the field.
The control of undesired vegetation is extremely important in order to achieve
high crop efficiency. Herbicides have a phytotoxic effect on plants, and so they
are used in plant production for controlling weeds or totally inhibiting their
growth. Herbicides can be non-selective, which means that they can destroy all
growth. Herbicides used to clear waste ground, industrial sites, railways and
railway embankments are non-selective and kill all plant material with which they
come into contact. Other types of herbicides are selective herbicides which kill
specific targets while leaving the desired crop relatively unharmed. Some of these
act by interfering with the growth of the weed and are often synthetic "imitations"
of plant hormones. However, these herbicides may not be effective against certain
type of other weeds. which may also be present in the crop to be protected.
Therefore, there is a strong need for mixing two or more herbic~des.
Unfortunately, most of such herbicides exhibit phytotoxicity to the economically
important plants as well as to the target plants called weeds which are sought to be
controlled. Phytotoxic means harmful impact on plant caused due to application of
any chemical/pesticide. The units used to measure the harmful impact of
chemical/pesticide are called phytotoxicity. More the phytotoxicity more the
damage caused to the plants. Phytotoxic effects caused by herbicides can be from
spray droplets, soil residues or vapours contacting sensitive plants. Phytotoxic
effects are measured by different means in plants like epinasty, hyponasty,
necrosis, vein clearing, wilting etc. Sometimes the damage appears as leaf
cupping, crinkling and speckling, distorted leaves, fruit, flowers or stems, change
in colour of leaves from light yellow to dark brown. Damage symptoms vary with
the herbicide and the type of plant that has been affected.
Mixtures of selected herbicides have several advantages over the use of a single
herbicide including (a) an increase in the spectrum of weeds controlled or an
extension of weed control over a longer period of time, (b) an improvement in
crop safety by using minimum doses of selected herbicides applied in combination
rather than a single high dose of one herbicide and (c) a delay in the appearance of
resistant weed species to selected herbicides (Int. J. Agri. Biol., Vol. 6, No. 1,
2004, pages 209-2121,
However. the activity and selective behaviour of a mixture is difficult to predict
since the behaviour of each single herbicide in the mixture is often affected by the
presence of the other(s) and the activity of the mixture may also vary considerably
depending on chemical character, plant species, growth stage, and environmental
conditions, which may result in reduced activity of the herbicides in the mixture.
In some cases, herbicidal active ingredients have been shown to be more effective
in combination than when applied individually and this is referred to as
"synergism." As described in the Herbicide Handbook of the Weed Science
Society of America, Eighth Edition, 2002, p. 462 "'synergism' [is] an interaction
of two or more factors such that the effect when combined is greater than the
predicted effect based on the response to each factor applied separately."
Applying combinations of two or more herbicides simultaneously to a field may
be necessary or desired for such synergistic effects other than an increased control
spectrum. For example, some herbicides have prolonged visual symptomology,
that is, it takes a relatively long period of time (i.e., up to two weeks or more) for
susceptible plants to show the visual effects of treatment. Generally, such
extended periods without any visual indication of herbicidal effectiveness detract
from the commercial value of herbicidal product. Therefore, it is often beneficial
to combine two or more herbicides in a tank mix or a package-mix that will
provide for more rapid bum down and earlier visual symptomology, thus
improving the value of the overall herbicidal product.
Package-mix fonnulations present numerous challenges to the formulator of
agricultural chemicals such as herb~cides. For example, the formulation should
contain the herbicidal active ingredients at as high a total concentration as
possible, for maximum convenience to the end user and to minimize packaging
and shipping costs, while keeping the active ingredients within the desired weight
ratios with respect to each other. Most importantly, the package-mix formulation
must exhibit sufficient physical and chemical stability to have an effective shelf
life of at least a few months, preferably at least a year, and ideally at least two
years.
The herbicidal compounds forming the synergistic composition of this invention
are already known individually for their herbicidal efficacy; display a synergistic
effect when applied in combination.
This invention relates to improved a) Imazethapyr and b) another herbicidal active
selected from a group of triazolinone herbicides comprising bencarbazone,
carfentrazone and sulfentrazone.
Imazethapyr is the common name used for 5-ethyl-2-[(RS)-4-isopropyl-4-methyl-
5-0x0-2-imidazolin-2-yllnicotinica cid having chemical formula C I S H I ~ Na~ndO ~
belonging to a relatively new substance class of herbicides, imidazolinones.
Imazethapyr is commonly described by following structure
Imazethapyr was first described in US 4798619 and reported by T. Malefyt et al.
(Abstr. 1984 Weed Science Society Mtg., Miami, p. 18, Abstract 49) 1984.
Imazethapyr is widely used for control of annual and perennial grass and broad
leaved weeds in major crops in particular, in soybean and groundnut. It acts by
inhibiting branched chain amino acids synthesis (ALS) due to which levels of
valine, leucine and isoleucine reduces, which leads to disruption of protein and
DNA synthesis. According to B. Tecle et al. Imazethapyr selectivity in soybean
and ground nut is mainly due to rapid detoxification via bydroxylation and
glycosylation (Proc. 199 7 Br. Crop Prot. Con$- Weeds, 2, 605). Imazethapyr is
commonly available in the market as 10 percent soluble liquid (SL) and 70
percent Water dispersible granules (WG) formulation. In accordance with an
aspect of the invention, Imazethapyr is present in an amount of 10% wlw.
For agriculture application, Imazethapyr herbicides suffer the disadvantage that
the desired efficacy on weeds starts declining after two or three years of regular
application. Moreover, despite being a selective herbicide, its pbyototoxic action
or phytotoxicity on desired crop and resistance in some annual grasses is reported
in the literature.
To counter this problem. thcrc is a long felt need in the art for Imazethapyr
formulations that solves the proble~no f phytotoxicity. Hitherto, no attempts have
been made to solve the phytotoxicity of Imazethapyr.
Moreover, Imazethapyr is a selective systemic herbicide which can be used to
control perennial grass and broad leaved weeds when applied as pre-plant, preemergence
or post-emergence in different crops. Major problem with selective
herbicides are their weed control spectrum (i.e. the weed controlled by particular
herbicide) which does not provide the overall weed control.
In view of the above, many tank mixes/combinations having Imazethapyr as major
constituent are available in the market to achieve the overall weed control. Paul F.
Myers and Harold D. Coble (Weed Technology Vol. 6, No. 2, 1992, pp. 333-338)
teaches that tank-mix combinations of imazethapyr with clethodim, fluazifop-P,
quizalofop, or sethoxydim, give good result. Literature is also available for
combinations of Imazethapyr with propiquizafop and cycloxydim. All these are
giving good results but still there is a scope for introduction of new innovation for
limiting the disadvantages associated with Imazethapyr with increase in efficacy
mainly due to following reasons
Phytotoxic effect on target crops as well as weeds thereby resulting in poor
plant growth and reduced yield.
Inability to achieve the overall weed control
Morco\.er all these mixtureslco~nbinations are applied as post emergence
i.e. after emergence of weeds which results in some losses to the crops
even if we achieve the complete control of weeds.
To counter these problems, there is a long felt need in the art for lmazethapyr
mixture/combination/tank mix that solves the problem of phytotoxicity along with
increase in efficacy to achieve overall weed control.
W.A van Saun et al. (Proceedings of' Br. Crop Protection conference-Weeds,
1991,1,77) describes a selective triazolinone herbicide N-[2,4-dichloro-5-[4-
(dif1uoromethyl)-4,5-dihydro-3-methyl-5-0x0H--1 l ,2,4-triazol-l -
yl]phenyl]methanesulfonamide which is commonly known as Sulfentrazone. Its
herbicidal activity is described in The Pesticide Manual, Seventeenth Edition,
2012. Sulfentrazone belongs to the family of Phenyltriazoles. These are organic
aromatic compounds containing a phenyl group substituted with a triazole ring
having following structure.
Sulfentrazone is a pre-emergence herbicide which has demonstrated herbicidal
efficacy against broad leaved weeds, some grasses and Cyprus species in soybean,
sugarcane and tobacco. Sulfentrazonc is absorbed by the roots 8L foliage. with
translocation primarily in the apoplasm, & limited movc~nent in the phloem and
acts through the inhibition ofprotoporphyrinogen oxidase in the chlorophyll
biosynthesis pathway, leading to the subsequent build-up of toxic intermediates.
Sulfentrazone is commonly formulated as suspension concentrate (SC)
formulation and is registered and marketed under the brand name of Authority.
However, Sulfentrazone suspension concentrate (SC) formulation (marketed as
Authority) is also known to produce phytotoxicity to desired crop. Such damage
affects the quality and overall yield of the desired crop. However, it is proven in
the art that sulfentrazone is not effective against some major grass weeds.
Sulfentrazone is also found pbytotoxic to the crops. Covesta Meeting,
Agronomy/Phytopathology, Montreux, 1997: 29 entitled "Effects of sulfentrazone
on weed control and phytotoxicity in flue-cured tabacco, by Smith W.D &
Peeding G" teaches that sulfentrazone is an effective herbicide, but it also causes
phytotoxicity when applied post-transplant. Reduced phytotoxicity was observed
when sulfentrazone was applied pre-transplant- incorporated. PCT publication
WO 2015200662 A1 describes a controlled release granular sulfentrazone
formulation so as to safen the plants by avoiding phyto-toxicity.
There is a further need in the art to provide synergistic herbicide compositions as
they afford various advantages. Herbicide combinations offer advantages of
improved weed control, a greater spectrum of weeds controlled, reduced cost and
reduced residue problems.
The present incention also provides such a synergistic herbicidal coniposition of
Irnazethapyr and sulfentrazone.
Hitherto, no attempts have been made to formulate a combination of lmazethapyr
and sulfentrazone. Therefore, there is a long felt need in the art to provide a stable
formulation comprising lmazethapyr and sulfentrazone that solves the problems
mentioned above and solves the existing problem of phytotoxicity induced by
these active ingredients.
The present invention provides such a storage stable agrochemical soluble liquid
(SL); suspension concentrate (SC) and dry flowable (DF) of Imazethapyr and
sulfentrazone that causes no phytotoxicity.
SUMMARY OF THE INVENTION
The present invention is broadly related to herbicidal compositions. In accordance
with one aspect of the invention there is provided a synergistic herbicidal
composition, comprising a combination of imazethapyr and sulfentrazone,
wherein imazethapyr and sulfentrazone are in a weight ratio ranging from about
5:1 to about 1:5.
In accordance with another aspect of the invention there is provided a herbicidal
formulation, comprising:
a. the synergistic herbicidal composition; and
b. agriculturally acceptable excipients.
The herbicidal formulation of the present invention may be in the ti)rn> of Dry
flowable (DF) formulation, Soluble liquid (SL) fonnulation, and Suspension
concentrate (SC) fonnulation.
The herbicidal formulation, is preferably in the form of a suspension concentrate
(SC) fonnulation, wherein imazethapyr is present in an amount of 6.00 to 35.00%
w/w and wherein sulfentrazone is present in an amount of 6.00 to 35.00% wlw.
The agriculturally acceptable excipients of the herbicidal formulation are selected
from the group consisting of antifreeze, dispersing agents, wetting agents,
antifoaming agents, biocides, thickeners and solvents.
The antifreeze is selected from propylene glycol, di-ethylene glycol and monoethylene
glycol, preferably propylene glycol, and present in an amount of 1.00-
8.00% wlw, preferably 5.00% wlw.
The dispersing agent is selected from mixture of nonionic surfactants and amine
salt of phosphate tristyryl phenol ethylated /Acrylic craft Copolymer1 ethoxylated
polyarylphenol phosphate ester, and present in an amount of 2.00-10.00% wlw,
preferably 4.00% wlw.
The wetting agent is non-ionic surfactant blend, and present in an amount of 2.00-
10.00% wlw, preferably 2.00% wlw.
The antifoaming agent is dimethyl polysiloxane emulsion, and present in an
amount of 0.01-0.5% wlw, preferably 0.20% wlw.
The biocide is selected from proxel GXL or formaldehyde, and prescnt 111 an
amount of 0.01-0.50% wiw, preferably 0.10% wiw.
The thickener is xanthan gum and present in an amount of 0.10-0.50% wiw,
preferably 0.10% wiw.
The solvent prescnt in the herbicidal formulation in the form of a suspension
concentrate (SC) is demineralised water.
The herbicidal formulation of the present invention has good stability, is nonphytotoxic
to commercial crops, affords simultaneous control of undesirable
weeds, particularly in oilseeds, cereals, tobacco, sugar cane etc. and also enhances
the vigourlyield, shows complementation of weed control spectrum over the
application of individual herbicide, and controls weed with a synergistically
effective amount of a combination of imazethapyr and sulfentrazone, which
denies the need of sequential application of herbicides to control different weed
spectra thereby reducing the environmental load of herbicides.
In accordance with yet another aspect of the present invention, there is provided a
process for preparing a herbicidal formulation in the form of a suspension
concentrate; comprising the steps of:
a. diluting and solubilising a dispersing agent and a wetting agent in
demineralised water in a high shear mixer;
b. adding an antifreezing agent, imazethapyr, an antifoaming agent, a
biocide, and sulfentrazone to the mixture of step a to form a
homogenous mass;
c. grinding the Iiornogcnous mass of step b in a bead mill t ~ l la mean
particle size of 3-5 p is obtained; and
d. adding a 2% solution of xanthan gum in water to the mixture of
step c under low stirring to form a homogenous mixture;
wherein added imazethapyr and sulfentrazone are in a weight ratio ranging frorn
about 5:l to about 1:s.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1. is a flow diagram for preparing a synergistic herbicidal composition in
the form of a suspension concentrate (SC).
DETAILED DESCRIPTION OF THE INVENTION
The invention according to its various aspects is particularly pointed out and
distinctly claimed in the appended claims read in view of this specification and
appropriate equivalents.
It is to be noted, as used in the specification and the appended claims, the singular
forms "a", "an", and "the" include plural referents unless the context clearly
dictates otherwise. Thus, for example, reference to a composition containing "a
compound includes a mixture of two or more compounds. It should also be noted
that the term "or" is generally employed in its sense including "and/or" unless the
content clearly dictates otherwise. The expression of various quantities in the
terms of "% wlw" or "%" means the percentage by weight, relative to the weight
of the total composition unless otherwise specified.
As used herein SL formulation. SC formulation and DF formulation are the
international denominations adopted by the FA0 (Food and Agriculture
Organization of the United Nations) to designate soluble liquid, suspension
concentrate and dry flowable, respectively.
The term "ago chemically effective amount" is that quantity of active agent,
applied in any amount which will provide the required control of broad leaved
weeds and grasses. The particular amount is dependent upon many factors
including, for example, the crop, weeds sought to be controlled and environmental
conditions. The selection of the proper quantity of active agent to be applied,
however, is within the expertise of one skilled in the art.
Many newer and conventional molecules are in practice in agriculture crops for
different weed management, but the indiscriminate use of these chemicals resulted
in reduced percent control due to build-up of the resistance in targeted weed
population. There are many reports on resistance of different weeds for different
molecules mainly due to either resistance or inactivity due to different reasons. To
overcome these problems grower is frequently prone to use repeated applications
of the herbicide where only one application is necessary. Other option is to either
mix other herbicides as readymade formulation or use different herbicides in
sequence. Second option is more costly as well as not environmental friendly as it
required repeated application and also more active is used thereby increases the
environmental load.
To counter this problem in an aspect of the invention there 1s provided an
herbicidal suspension concentrate (SC) that does not cause phytotoxicity to
commercial crops and the methods of preparing the same.
Yet another aspect of the present invention is to provide a non-phytotoxic
herbicidal suspension concentrate (SC) comprising agrochernically effective
amount of Imazethapyr and Sulfentrazone which complements each other to
enhance weed control spectrum required for overall weed control and also
enhances the vigourlyield of the plant.
Another aspect of the invention is to prepare a formulation comprising
Imazethapyr with Sulfentrazone in a weight ratio of from about 5: 1 to 1 :5.
According to another aspect of the present invention Imazethapyr is present in an
amount of 6.00-35% wlw.
According to another aspect of the present invention sulfentrazone is present in
the range from 6.00 to 35.00%.
According to another aspect of the present invention, the synergistic herbicidal
combination fhrther comprises a plurality of different excipients selected from
anti-freeze agents, dispersing agent, wetting agents, de-foaming or antifoaming
agents, biocides, thickeners or thickening agents and solvent.
In accordance with yet another aspect of the invention, the anti-freezing agent is
present in an amount of 1.00-8.00% wlw and more preferable 5.00% wlw.
In accordancc \zit11 yet another aspect of the invention, the anti-freezing agent is
selected from propylene glycol, di-ethylene glycol, mono-ethylene glycol or in
combination thereof. In a preferred aspect of the invention, the anti-freezing agent
is preferably propylene glycol.
In accordance with yet another aspect of the invention, the dispersing agent is
present in an amount of 2.00-10.00% w/w and more preferable 4.00% w/w.
In accordance with yet another aspect of the invention, the dispersing agent is
selected from Mixture of nonionic surfactants & Amine salt of phosphate tristyryl
phenol ethylated /Acrylic craft Copolymer1 ethoxylated polyarylphenol phosphate
ester or in combination thereof.
In accordance with yet another aspect of the invention, the wetting agent is present
in an amount of 2.00-10.00% wlw and more preferable 2.00% wlw.
In accordance with yet another aspect of the invention, the wetting agent is
Nonionic surfactant blend.
In accordance with yet another aspect of the invention, the anti-foaming agent is
dimethyl polysiloxane emulsion and present in an amount of 0.01-0.50% wlw and
more preferable 0.20% wlw.
In accordance with yet another aspect of the invention, the biocide is selected
from Proxel GXLJ Formaldehyde and present in an amount of 0.01-0.50% wlw
and more preferable 0.10% wlw.
In accordance with yet another aspect of the invention, the thickener is xanthan
gum and present in an amount of 0.10-0.50% wlw and more preferable 0.10%
wlw.
In accordance with yet another aspect of the invention, the synergistic herbicidal
composition further comprises demineralized water to make up to volume.
Another aspect of the present invention is to provide herbicidal composition
which is having good stability.
According to another aspect of the present invention is to provide an herbicidal
composition which demonstrates a complementation of weed control activity over
the application of individual herbicides separately. Yet another aspect of the
present invention is to provide a synergistic herbicidal combination that negates
the need of the sequential application of herbicides thereby reducing the
environmental load of herbicides and thus are environmentally safe.
The present invention is more particularly described in the following examples
that are intented as illustrations only, since numerous modifications and variations
within the scope of the present invention will be apparent to those skilled in the
art. Unless otherwise noted, all parts, percentages, and ratios reported in the
following examples are on a weight basis and all reagent used in the example were
obtained or are available from the chemical suppliers.
EXAMPLES
The following examples illustrate the basic methodology and versatility of the
present invention.
Examples 1-4
The unit of each value below is "% wlw" i. e. the percentage by weight, relative to
the weight of the total solution or composition unless otherwise specified. The
compositions contemplated by each of the Examples 1-4 that are tabulated in
Table 1 are formulated as a suspension concentrate (SC) formulation.
Table 1: Synergistic herbicidal composition
Component Function Examples
1 2 3 4
Imazetliapyr "A.1 30.00 33.00 7.5 6.67
Sulfentrazone **A.I 7.5 6.67 30.00 33.00
Propylene glycol Antifreeze 5.00 5.00 5.00 5.00
agent
Acrylic craft copolymer Dispersing 4.00 4.00 4.00 4.00
Agent
Nonionic surfactant blend Wetting Agent 2.00 2.00 2.00 2.00
Dimethyl polysiloxanc Anti-foaming 0.20 0.20 0.20 0.20
emulsion agent
Proxel GXL Biocide 0.10 0.10 0.10 0.10
Xanthan Gum Thickener 0.10 0.10 0.10 0.10
Demineralized Water Solvent *q.s. *q.s. *q.s. *q.s.
A.I.= Active Ingredient
Q.S.= quantity Sufficient
The aforementioned herbicidal composition can be formulated as suspension
concentrate (SC) by the process described in Example 5 below
Example 5
Process for preparing synergistic herbicidal composition in the form of
suspension concentrate (SC) formulation.
The herbicidal compositions of Examples 1-4 are prepared by the process
described hereinafter and also depicted in figure 1. All the raw materials were
verified for conformance to the laid down individual specifications. The raw
materials required for preparing compositions of examples 1 to 4 are illustrated in
table 2 under the column headings 1 to 4 respectively. Entries for sulfentrazone
and imazethapy in table 2 differ from those in table 1 as entries in table 1 are for
100% pure compounds, whereas those in table 2 are for technical ones, i.e. those
containing a certain percentage of impurities.
The amounts of active ingredients presented in table 2 may be greater than the
values calculated taking into account the percentage purity of the active
ingredients, to compensate for losses of said ingredients during the manufacturing
process. It was observed that following said procedure on industrial scale the final
yield of A.I. will be similar or same as to standardized values.
The required quantities of raw materials as illustrated in Table 2 below were
weighed, and transferred through the auto-hatching system. The dispersing and
wetting agents are first diluted in Demineralized (D.M) Water, and solubilized by
high shear mixer, followed by adding anti- freezing agent, Imazethapy technical,
anti-foaming agent, and biocide and mixed to make a homogeneous mixture.
Sulfentrazone technical is then added and mixed to make homogeneous mass.
'I'hc above homogenous mass is grindcd in Bead Mill till a Incan particle size of 3-
5(D-90) microns is obtained. After obtaining said mean particle size a 2% solution
of xanthan gum in demineralized water is added under low stirring.
After homogeneous mixing, the quality of in-process sample was checked for
conformance to the laid out specifications. The quality approved in-process
sample was transferred to the holding tank after passing through sparkler filter
pump for packing as per the requirements.
Table 2: Quantities of the active ingredients and raw materials charged
Component Function Quantities of materials charged
1 2 3 4
Imazethapyr Technical **A1 33.34 36.67 8.34 7.42
(Based on 90.0% wiw
minimum)
Sulfentrazone Technical **A.I 7.00 7.03 31.58 34.74
(Based on 95.0% wlw
minimum)
Propylene glycol Antifieeze 5.00 5.00 5.00 5.00
agent
Acrylic craft copolymer Dispcrsing 4.00 4.00 4.00 4.00
Agent
Nonionic surfactant blend Wetting 2.00 2.00 2.00 2.00
Agent
Dimethyl polysiloxane Anti-foaming
0.20 0.20 0.20 0.20
emulsion agent
Proxel CXL Biocide 0.10 0.10 0.10 0.10
Xanthan Gum Thickener 0.10 0.10 0.10 0.10
Demineralized Water Solvent 47.36 44.90 48.68 46.44
**A.I. =Active ingredient
Example 6
Evaluation of the synergistic effect for herbicidal combination of
lmazethapyr and Sulfentrazone
The performance of the herbicidal composition according to the present invention
(Imazethapyr + Sulfentrazone) was co~nparcd against thc known comnpositio~lso f
Sulfentrazone 39.6% SC and lma~ethapyr 1096 SL. which were evaluated against
weed spectrum in soybean and also the vigourlyield of the crop was tested. Area
for experiment was marked for different plot sizes and pre-emergent chemical
application was made using high volume knapsack sprayer. Experimental design
was in randomized blocks with five replication aid each plot was measured an
area of 100 sq. mts (10 x 10 mts). Observation on weed population, dry weight
and weed control efficiency (WCE %) was assessed at 4 days after application.
Table 3 below summarizes the synergistic effect exists whenever the action of an
active ingredient combination is greater than the sum of the actions of the
individual components i.e. Imazethapyr and Sulfentrazone against different weed
spectrum at different concentrations.
Weed control efficiency (WCE%) =
weed dry weight in untreated plot - weed dry weight in treated plot
xl00
weed dry weight in untreated plot
In the ficld of agriculture. it is often understood that the tern "synergy" is as
defined by Colby S. R. in an article entitled "Calculation of the synergistic and
a~ltaconisticr csponscs of hcl-l~icidco inbination>" puhlishctl i l l tl~cio u~ncilL Vccds.
1 15, p. 30-22. l'he action expected fix a giwn colnhination ol'twu active
ccrmpo~icn~sccbac calculated as follows:
Where,
E = Expected percentage of herbicidal control for the combination of the two
herbicides at defined doses (for example equal to x and y respectively),
X = X is the percentage of herbicidal control observed by the compound (I) at a
defined dose (equal to x),
Y = Y is the percentage of herbicidal control observed by the compound (11) at a
defined dose (equal to y),
When the percentage of herbicidal control observed for the combination is greater
than the expected percentage, there is a synergistic effect.
Table 3: Synergistic overall weed spectrum at different concentrations of
synergistic herbicidal composition comprising Imazethapyr and
Sulfentrazone
-
Compound A.I.(g/ha) WCE Expected Colby's
(%)at 45 Control Ratio
DAA* (Ed (Ea+dEt)
-- -
Imazethapyr
lmazethapyr 115.5 E,2 = 50.21
lmazethapyr 90 Ea3 = 44.46
Imazethapyr 73.37 E,4 = 42.75
Sulfentrazone 26.25 Ebl = 4.33 -
Sulfentrazone 23.35 Eb2 = 3.67 -
Sulfentrazone 360 Eb3 = 39.27 -
Sulfentrazone 363 Eb4 = 40.00
Imazethapyr
Sulfentrazone
Imazethapyr
Sulfentrazone
Imazethapyr
Sul fentrazone
Imazethapyr
Sulfentrazone
DAA = Days after application
Ea = % WCE aher 45 DAA for lrnazethapyr
Eb = 96 WCE after45 DAA for Sulfentrazone
Ea+b = % WCE after 45 DAA for lmarethapyr + Sulfentrazone
Et = Expected %WCE aher 45 DAA for lrnarethapyr and Sulfentmrone in combination fmln alone
It can be seen from the data presented in Table 3, comb~natiorio f lrnazethapyr and
Sulfentrazone at all the doses demonstrate synergistic effect against different weed
population.
Example 7: Bio-efficacy of herbicidal combination of lmazethapyr and
Sulfentrazone against overall weed spectrum in soybean crop
Field trials were performed to evaluate the biological efficacy of the herbicidal
combination of present invention (Imazethapyr + Sulfentrazone) against the
overall weed spectrum in the field at various trial sites. This evaluation was
performed by comparing the claimed herbicidal combination in the present
specification against the marketed reference products, i.e., Sulfentrazone 39.6%
SC and Imazethapyr 10% SL.
Area for experiment was marked for different plot sizes and pre-emergent
chemical application was made using high volume knapsack sprayer. Based on
various doses, weighed quantity of test products were dissolved in 5 lit. of
waterltreatment and sprayed uniformly. Experimental design was in randomized
blocks with five replication and each plot was measured an area of 100 sq. mts (10
x 10 mts). Observation on weed population, dry weight and weed control
efficiency (WCE%) was assessed at 15, 30 and 45 days after application and
expressed as mean of all three observation.
Details of Experiment
Target weeds: Overall weed spectrum
Crop: Soybean
Application Method: high volume knapsack sprayer fitted with tlat fan nozzle
The treatment details are tabulated in Table 4 below.
Table 4: Treatment details for evaluation of Bio-efficacy of herbicidal
composition against weed spectra in soybean
Particular Treatment Dose /ha Time of
Application
TI Imazethapyr 30% + Sulfentrazone 7.5% 350 ml Pre-
SC emergence
application
T2 Imazethapyr 33% + Sulfentrazone 6.67% 350 ml
T3 Imazethapyr 7.5% + Sulfentrazone 30% 1200 ml
SC
T4 Imazethapyr 6.67% + Sulfentrazone 33% I100 ml
SC
TS Sulfentrazone 39.6% SC and 750 ml
T6 Imazethapyr 10% SL 1000 ml
T7 Control (Water Spray) -- -.
TIlc bio-efficacy effect of different treatment schedules on soybean crop and the
treatment wise yield data of soybean crop is summarized in Table 5-6 below.

I I I I I I * DAT: Davs affer treatment; SEm *: Standard Errors ofMeans; CD 5%: Critical Difference; g = Gram; m' = Square meter; ml = Millilitre
-
--
I I I I I I
* Value in Parentheses is transformed value
(6.56)
99.11
(9.98)
7 --
SEm k
(7.90)
145.89
(12.10)
1.93
T7
-- ..
Control (Water Spray)
1.77
Table 6: Treatment Wise Yield Data of Soybean Pods
Treatment Pod Yield (qtlha)
*SEm i: Standard Errors of Means; CD 5%: Critical Dtference
TI
T2
T3
T4
Ts
T6
T7
SEm i
CD 5%
Data presented in table 5 and 6 shows that weed population was significantly
affected by all the treatments against control. Lowest mean weed population was
observed in T3 followed by Tq, T2 and TI. Similar effect was observed with Weed
8.62
--
8.80
9.23
9.36
7.36
7.23
5.09
0.23
0.69
dry weight and WCE where highest WCE of 86.07 was observed in plots treated
with T4 followed by T,, Tz and TI.
Example 8: Phytotoxic effect of herbicidal combination of lmazethapyr and
Sulfentrazone in soybean
Visual observation on phytotoxicity were recorded for leaf injury on tiplsurface,
EpinastyIHyponasty, and wilting, etc. on 0-10 scale (as below) at 1, 3, 7, 14 and
21 days after each application from each and then average was taken.
No phytotoxicity
DGA = Days after application L = Leaf injury to tipisurface
E/H = EpinastyIHyponasty W = Wilting
Table 7: Effect of herbicidal composition on the Phytotoxicity in Soybean
ity Days after Application(DAA)
O= No Phytoxicity
Table 7 above shows that combination of Imazethapyr and Sulfentrazone
formulated as SC did not show any phytotoxicity even at double the dose.
Conclusion:
1. It was thus surprisingly found that the herbicidal combination of
Imazethapyr and Sulfentrazone gave excellent weed control in soybean
crop and is significantly superior over individual commercial products.
2. Highest pod yield of soybean was recorded in treatment of Imazethapyr
6.67% + Sulfentrazone 33% SC in the dose of 1100 mlha; i.e. 9.36 qt/ha,
which was statistically significant over all other treatments.
3. It was also found that no phytotoxicity was observed in case of
Imazethapyr and Sulfentrazone at standard as well as double the standard
dose.
From the foregoing it will be observed that numerous modifications and variations
can be effectuated without departing from the true spirit and scope of the novel
concepts of the present investigation. It is to be understood that no limitations with
respect to the specific embodiment illustrated is intended or should be inferred. It
should be understood that all such modifications and improvements have been
deleted herein for the sake of conciseness and readability but are properly within
the scope of the following claims.

We Claim:
1. A synergistic herbicidal composition, coinprising a comb~nation of
iinazethapyr and snlfentrazone.
2. The synergistic herbicidal composition, as claimed in claim 1, wherein
imazethapyr and sulfentrazone are in a weight ratio ranging from about 5: 1
to about 1 :5.
3. A herbicidal formulation, comprising:
a. the synergistic herbicidal composition, as claimed in claims 1 and
2; and
b. agriculturally acceptable excipients.
4. The herbicidal formulation, as claimed in claim 3, wherein the formulation
is in the form of Dry flowable (DF) formulation, Soluble liquid (SL)
formulation, and Suspension concentrate (SC) formulation.
5. The herbicidal formulation, as claimed in claim 4, wherein the formulation
is preferably suspension concentrate (SC) formulation, wherein
imazethapyr is present in an amount of 6.00 to 35.00% wlw and wherein
sulfentrazone is present in an amount of 6.00 to 35.00% wlw.
6. The herbicidal formulation, as claimed in claims 3, 4 and 5, wherein the
agriculturally acceptable excipients are selected from the group consisting
of antifreeze, dispersing agents, wetting agents, antifoaming agents,
biocides, thickeners and solvents.
7. The herbicidal formulation, as claimed in claim 6, wherein the antifreeze is
selected from propylene glycol, di-ethylene glycol and mono-ethylene
glycol. preferably propylene glycol, and present in an amount of 1.00-
8.00% wlw, preferably 5.00% wiw.
8. The herbicidal fonnulation, as claimed in claim 6, wherein the dispersing
agent is selected from mixture of nonionic surfactants and amine salt of
phosphate tristyryl phenol ethylated /Acrylic craft Copolymer/ ethoxylated
polyarylphenol phosphate ester, and present in an amount of 2.00-10.00%
W/W, preferably 4.00% wlw.
9. The herbicidal formulation, as claimed in claim 6, wherein the wetting
agent is non-ionic surfactant blend, and present in an amount of 2.00-
10.00% wlw, preferably 2.00% wlw.
10. The herbicidal formulation, as claimed in claim 6, wherein the antifoaming
agent is dimethyl polysiloxane emulsion, and present in an amount of
0.01-0.5% wlw, preferably 0.20% w/w.
11. The herbicidal formulation, as claimed in claim 6, wherein the biocide is
selected from proxel GXL or formaldehyde, and present in an amount of
0.01-0.50% wlw, preferably 0.10% wlw.
12. The herbicidal formulation, as claimed in claim 6, wherein the thickener is
xanthan gum and present in an amount of 0.10-0.50% wlw, preferably
0.10% wlw.
13. The herbicidal formulation, as claimed in claim 6, wherein the solvent is
demineralised water.
14. The herbicidal formulation, as claimed in claims 3-13, wherein the
herbicidal formulation has good stability.
IS. The herbicidal foniiulation, as claimed in claims 3-13. wherein the
herbicidal fonnulation is non-phytotoxic to commercial crops.
16. The herbicidal formulation, as claimed in claims 3-13, wherein the
herbicidal formulation affords simultaneous control of undesirable weeds,
particularly in oilseeds, cereals, tobacco, sugar cane etc. and also enhances
the vigourlyield.
17. The herbicidal formulation, as claimed in claims 3-13, wherein the
herbicidal formulation shows complementation of weed control spectrum
over the application of individual herbicide.
18. The herbicidal formulation, as claimed in claims 3-13, wherein the
herbicidal formulation controls weed with a synergistically effective
amount of a combination of imazethapyr and sulfentrazone, which denies
the need of sequential application of herbicides to control different weed
spectra thereby reducing the environmental load of herbicides.
19. A process for preparing a herbicidal formulation in the form of a
suspension concentrate; comprising the steps of:
a. diluting and solubilising a dispersing agent and a wetting agent in
demineralised water in a high shear mixer;
b. adding an antifreezing agent, imazethapyr, an antifoaming agent, a
biocide, and sulfentrazone to the mixture of step a to form a
homogenous mass;
c. grinding the homogenous mass of step b in a bead mill till a mean
particle size of 3-5 p is obtained; and
d. adding a 2% solution of xanthan gum in watcr to the mixture of
step c under low stirring to form a homogenous mixture;
wherein added imazethapyr and sulfentrazone are in a weight ratio
ranging from about 5: 1 to about 1 :5.