DESC:FIELD OF THE INVENTION
The present invention relates to a synergistic agrochemical composition comprising hexaconazole and carbendazim. The present invention also relates to an agrochemical composition comprising of hexaconazole, carbendazim and agriculturally acceptable excipients having high stability and enhanced efficacy.
BACKGROUND OF THE INVENTION
This section includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the present invention, or that any publication specifically or implicitly referenced is prior art.
Agrochemical compositions can be in the form of solutions, emulsions, suspensions, dispersions and the like. The typical agrochemical compositions include pesticides such as herbicides, insecticides, fungicides, growth regulators and the like.
In recent years, in view of the environmental concern and to achieve results in very economical way, various attempts have been made to maximizing the performance of known active ingredients. The usual components of formulations such as carriers and inert ingredients (e.g. organic solvents, suspension agents, emulsifiers, surfactants, wetting agents, solubilizing agents) which do not themselves possess biological effect, usually not lead to an increase in biological efficacy of agrochemical composition.
International Patent Application WO 95/01722 discloses pesticidal formulations containing non-ionic surface-active agents which can be selected, inter alia, from liquid polyalkoxylated aliphatic alcohols. However, the addition of these agents is directed to improving the storage stability of the formulations, and there is no report of enhancing the activity of fungicides used in the formulations.
Many agrochemical compositions require the addition of an adjuvant to provide wetting and penetrating effects especially on foliar surfaces. Regarding the uptake of the active ingredient into the leaf, surface-active substances may act as modifiers and activator. In general, it is assumed that suitable surface-active substances can increase the effective contact area of liquids on leaves by reducing the surface tension. Moreover, surface-active substances can dissolve or break up the epicuticular waxes, thereby facilitating the absorption of the active ingredient. Furthermore, some surface-active substances can also improve the solubility of active ingredients in formulations and thus avoid, or at least delay, crystallization. Surfactant-type adjuvants are exploited in a number of ways for agro-technical applications. They can be divided into groups of anionic, cationic, nonionic or amphoteric substances.
The choice of formulation type and inert ingredients for that formulation such as surfactants often determines to a significant extent whether the active ingredients can display its full efficacy on application. Thus, where the treatment with a particular active ingredient is not satisfactory, it may be treated successfully by the addition of particular adjuvant.
The addition of certain adjuvant to agrochemical compositions has the advantage that the amounts of active ingredients in the formulation may be reduced while maintaining or enhancing the pesticidal activity, thus allowing costs to be kept as low as possible. Often that adjuvant is a surfactant, which can perform a variety of functions, such as increasing spray droplet retention on difficult to wet leaf surfaces, or to provide penetration of the pesticides into the plant cuticle. However, not every surfactant can increase the biological efficacy or uptake of any pesticide as there is no practical theory or comprehensive model that can predict quantitatively the effect of the same and thus complex systematic studies are needed to elucidate the mechanisms involved in interaction between pesticides, surfactants and plants.
It is therefore one of the aim of the present invention to provide selection of particular surfactant, rheology modifier, dispersing agent and wetting agent for an agricultural formulation comprising hexaconazole, carbendazim to prevent Ostwald ripening and also to increase the biological efficacy thereof.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a composition comprising hexaconazole and carbendazim in a particular relative ratio which shows markedly improved biological efficacy.
It is also another object of the present invention to provide a composition comprising hexaconazole, carbendazim and agriculturally acceptable excipients having markedly improved stability and biological efficacy.
It is yet another object of the present invention to provide a low dose effective formulation comprising hexaconazole and carbendazim for treatment of broad spectrum fungal diseases of agricrops.
These and other objects and features of the invention will become more apparent from the detailed description set forth herein below.
SUMMARY OF THE INVENTION
In accordance with one of the embodiment of the present invention, a synergistic fungicidal composition comprising hexaconazole and carbendazim.
In accordance with one of the embodiment of the present invention, weight ratio of hexaconazole and carbendazim in a synergistic fungicidal composition comprising hexaconazole and carbendazim is in the range from about 1:1 to 1:10.

In accordance with one of the embodiment of the present invention, a synergistic fungicidal composition comprises hexaconazole in an amount of about 1-10% by weight of the composition and carbendazim in an amount of about 1-20% by weight of the composition.

In accordance with one of the preferred embodiment of the present invention, the composition comprises hexaconazole in an amount of about 4% by weight of the composition and carbendazim in an amount of about 16% by weight of the composition.

In accordance with one of the embodiment of the present invention, the synergistic fungicidal composition further comprises one or more agriculturally acceptable excipients.

In accordance with one of the embodiment of the present invention, the agriculturally acceptable excipients are selected from the group consisting of a solvent, a surfactant, an emulsifier, a dispersing cum wetting agent, a defoamer, an anti-freezing agent, a thickner, a biocide and a rheology modifier.

In accordance with one of the embodiment of the present invention said rheology modifier is silicone ethoxylate.

In accordance with one of the embodiment of the present invention said silicone ethoxylate is trisiloxane ethoxylate.

In accordance with one of the embodiment of the present invention said dispersing agent is a polymeric surfactant based on C9-C15 acrylate as hydrophobe and sulfonic acid group as hydrophilic.

In accordance with one of the embodiment of the present invention, the synergistic fungicidal composition comprising hexaconazole and carbendazim is formulated as a suspension concentrate (SC), an emulsifiable concentrate (EC), a micro emulsion (ME), an encapsulated suspension (CS), or a water dispersible granule (WG)

In accordance with one of the preferred embodiment of the present invention, the synergistic fungicidal composition comprising hexaconazole and carbendazim is formulated as a suspension concentrate (SC).

DESCRIPTION OF THE INVENTION
The following is a description of embodiments of the present invention. The embodiments are in such details as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.
Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including”, but not limited to.”
As used in the description herein and throughout the claims that follow, the meaning of “a”, “an” and “the” includes plural reference unless the context clearly dictates otherwise.
In some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment.
The present invention concerns with the enhancement of the biological efficacy of a composition comprising hexaconazole and carbendazim. In accordance with one of embodiment of the present invention, a composition comprising hexaconazole and carbendazim shows maximum biological efficacy when in the composition, hexaconazole is present in an amount of 1% to 10% by weight of the composition and carbendazim is present in an amount of 1% to 20 % by weight of the composition. Preferably, in the composition comprising hexaconazole and carbendazim, weight percentage of hexaconazole is 4% and weight percentage of carbendazim is 16%.
The pesticide composition of the present invention being employed preferably together with at least one of the agriculture acceptable excipient depending upon the type of formulation prepared. Suitable auxiliaries which may be comprised in the composition according to the invention are all customary formulation adjuvants or components, such as extenders, carriers, solvents, surface-active compounds, dispersing agents, wetting agents, anti-freezing agents, anti-foaming agent, biocides, rheology modifier, preservatives, antioxidants, colorants, thickeners, solid adherents and inert fillers.
Depending on the aims to be achieved and the given circumstances, the pesticides according to the invention include emulsifiable concentrates, suspension concentrates, directly sprayable or dilutable solutions, spreadable pastes, dilute emulsions, sprayable powders, soluble powders, dispersible powders, wettable powders, dusts, granules or encapsulations in polymeric substances.
In accordance with another embodiment of the present invention, a silicone ethoxylate rheology modifier is added to a composition comprising hexaconazole and carbendazim formulated in a suspension concentrate form, in order to improve the properties such as rheology modification along with spreading coverage and enhance penetration of the active ingredient into the plant, therefore gaining improved coverage and adhesion, to efficiently control various plant diseases. Preferably, a trisiloxane ethoxylate is used in the present invention.
In accordance with another embodiment of the present invention, the crystal growth formation and gelling behavior in a composition comprising hexaconazole and carbendazim formulated in a suspension concentrate form is controlled by properly selecting anti gel forming and anti-caking agents selected from one or more of the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol and alkylated ethoxylated phosphate esters.
The problem encountered in preparing the suspension concentrate formulation of hexaconazole and carbendazim was primarily the occurrence of Ostwald ripening or polymorphism during storage. This was more prominent and accelerated by temperature cycling. The value of Ko/w logP for hexaconazole is 3.9 and its solubility in methanol is 246 g/l. These factors led to crystallization proceeds vide nucleation and growth. The use of phosphate esters as suspending agent in the formulation led to the phenomenon of Ostwald ripening also because of partial formation of carbendazim phosphate whose solubility in water is 9 g/l. The formulation was modified and in place of phosphate esters as suspending agent, the polymeric surfactant based on C9-C15 acrylates as hydrophobe and sulfonic acid group as hydrophilic were found to eliminate the phenomenon of Ostwald ripening. EP2164322B1 describes the phenomenon of crystal growth in azole pesticides and that was overcome by the use of carboxylic acid amides such as N,N-diethyloctadecanamide. But in the present invention, we have observed that the use of acryl amide group in the hydrophile of polymeric surfactant helped in prevention of Ostwald ripening. Further, the use of silicone ethoxylate provided steric and electrostatic repulsion which led to decrease in viscosity during storage and prevented nucleation and growth. For rheology modification several clays were tried but silica found the best in the present system of adjuvants to avoid nucleation.
The components in suspension concentrate formulation may be present in any suitable amount, and generally, said formulation comprising 1% to 10% of hexaconazole, 1% to 20 % of carbendazim, 1% to 5% of dispersing agents, 1% to 5% of wetting agents, 0.5% to 5% of surfactants, 3% to 8% of anti-freezing agents, 0.1% to 1.0% of antifoaming agents, 0.1% to 1.0% of biocide, 0.1% to 1% of rheology modifier by weight of the composition and rest of suitable solvent.
The following examples of formulations according to the invention are presented to illustrate, but not to restrict, this invention:
FORMULATION EXAMPLES
A suspension concentrate formulation having the following composition (hereinafter referred to as “IIL-HEXACARB”) was prepared by following the process as known in the art:
Ingredient Concentration (% w/w)
Hexaconazole 4
Carbendazim 16
Polymeric acrylic surfactant 3.0
Polyoxyalkylene alkyl C12-C15 ether 2.0
Silica 1.0
Glycol 5.0
Silicone antifoam 0.5
Trisiloxane ethoxylate 1.0
Rhodopol 23 0.25
DM water 67.25
The following field tests were performed to evaluate the bio-efficacy of the IIL-HEXACARB on Paddy for the control of sheath blight and blast diseases:
Introduction:
Leaf blast and Sheath blight disease of rice are the important limiting factors of rice productivity all over the world including in India. These diseases are more important in intensive cultivation system where paddy will be grown under elevated fertilizers doses especially the Nitrogen fertilizer. Due to non availability of resistance source for sheath blight and non availability of location specific resistance varieties for blast diseases, the chemical control is an important strategy for the farmers to harvest the economic yield. Moreover, poor bio-efficacy of the biocontrol agents under the severe epidemic condition makes the chemical control an inevitable and ultimate means for the farmers. In view of this, IIL-Hexacarb has been developed and tested for its bio-efficacy against blast and sheath blight disease of paddy during Rabi.
1. Crop & Variety : Rice (Variety: BPT5204)
2. Location : AICRP-Rice, ARS, Gangavathi (UAS Raichur), Karnataka
3. Experimental design : Randomized Block Design (RBD)
4. Replication : 3
5. Treatments : 8
6. Plot size : 40 sq.m
7. Spacing : 20 cm X 15 cm
8. Number of plants/plot : 1333 clumps
9. Type of Formulation : Suspension Concentrate (SC)
10. Method of Fungicide Application : Foliar spray
11. Dose Rate : As described in Table 1
12. Number of samples taken/treatment : Details given in the methodology

Materials & Methods:
Evaluation of IIL-Hexacarb was carried in Rabi on blast and sheath blight diseases of rice at the AICRP-Rice, ARS, Gangavathi (UAS Raichur), Karnataka. The experimental plots were laid out in randomized block design with three replications of seven treatments (Table 1). Two sprays of the fungicide were made at 15 days interval. The test fungicides were applied by using Knapsack sprayer fitted with hollow cone nozzle with 500 liter/ha water volume. Observations were recorded on disease severity in each treatment before and 7 and 14 days after each spray as per the standard method. The observations of severity of blast and sheath blight diseases were recorded using 0-9 scale (SES, IRRI, 1996). In each replicated plot of the treatments, twenty hills were selected randomly and scored as per scale. The percent disease index (PDI) of plants was calculated by the following formula.
Sum of numerical rating
PDI = X 100
Total no. of hills observed X Maximum grade

Scale for sheath blight disease (SES 0-9, IRRI, 1996)

Sr. No. Description Score
1 No infection 0
2 Vertical spread of the disease up to 20% of plant height 1
3 Vertical spread of the disease up to 21-30% of plant height 3
4 Vertical spread of the disease up to 31- 45% of plant height 5
5 Vertical spread of the disease up to 46 – 65% of plant height 7
6 Vertical spread of the disease more than 66% of plant height 9

Scale for leaf blast disease evaluation (SES 0-9, IRRI, 1996)

Description Score
No lesions 0
Small brown specks of pinhead size without sporulating center 1
Small roundish to slightly elongated, necrotic grey spot about 1-2 mm in diameter with a distinct brown margin and lesions are on lower surface 2
Same as Score 2 but significant number of lesions on upper surface 3
Typical sporulating blast lesions, 3 mm or longer, infecting <2% of area 4
Typical blast lesion infecting 2-10% of the leaf area 5
Blast lesions Infecting 11-25% leaf area 6
Blast lesions Infecting 26-50% leaf area 7
Blast lesions infecting 51-75% leaf area 8
>75% leaf area affected 9

Table 1: Treatment Details
Sl. No Treatment Dose (g/ml/ha)
1 IIL-HEXACARB 600
2 IIL-HEXACARB 750
3 IIL-HEXACARB 900
4 HEXACONAZOLE 5% SC 1000
5 CARBENDAZIM 50% WP 500
6 TEBUCONAZOLE 25.9% EC 750
7 CONTROL -

Results:
It has been found that IIL-HEXACARB@ 750-900 ml/ha was significantly reduced the blast and sheath blight diseases over rest of the treatments and hence, improved the yield. The details of the results are described below.

Blast disease:
The fungicide tested against Blast disease during Rabi revealed that, the treatment plot sprayed with that IIL-HEXACARB @ 900 ml/ha after two applications at 15 days interval recorded least PDI of blast disease and was significantly superior over control treatment. The same dose was significantly on par with that IIL-HEXACARB 5% SC @ 750 ml/ha. Whereas, standard check treatments such as Hexaconazole @ 1000 ml/ha, Carbendazim 50% WP @ 500 g/ha and Tebuconazole 25.9% EC @ 750 ml/ha were on par among themselves but recorded significantly more PDI over that IIL-HEXACARB @ 750-900 ml/ha at final observation. Maximum PDI was recorded in untreated control (Table 2).
Sheath Blight disease:
The fungicides tested against sheath blight disease during Rabi revealed that, the treatment plot sprayed with IIL-HEXACARB @ 750 ml/ha after two applications at 15 days interval recorded least PDI of sheath blight disease and was significantly superior over control treatment. The same dose was significantly on par with IIL-HEXACARB@ 900 ml/ha. Whereas standard check treatments such as Hexaconazole @ 1000 ml/ha, Carbendazim 50% WP @ 500 g/ha and Tebuconazole 25.9% EC @ 750 ml/ha were on par among themselves but recorded significantly more PDI over that IIL-HEXACARB@ 750-900 ml/ha at final observation. Maximum PDI was recorded in untreated control (Table 3).

Yield:
The difference in the yield level between treated and untreated plots were very much significant (Table 4). During the experiment period highest yield (57.13 q/ha) was recorded in the plot treated with the IIL-HEXACARB @ 900 ml/ha and it was on par with the IIL-HEXACARB @ 750 ml/ha (56.59/ha). The lowest yield was recorded in the untreated plot (35.92/ha) (Table 4).

Table 2: Effect of IIL-HEXACARB application of against blast disease on rice during Rabi.

SL. No Treatments Doses (ml or
gm/ ha) Blast disease PDI Percent disease Control over untreated control
Before Spray Ist Spray Percent disease Control over untreated control IInd Spray
7 days after spray 14 days after spray 7 days after spray 14 days after spray
1 IIL Hexacarb 600 33.33 23.33 24.07 44.44 18.88 19.25 63.13
2 IIL Hexacarb 750 28.88 16.29 17.03 60.69 14.07 14.44 72.34
3 IIL Hexacarb 900 25.55 15.18 16.66 61.54 12.22 12.96 75.18
4 Hexaconazole 5% SC 1000 33.55 28.14 29.25 32.48 26.29 27.03 48.23
5 Carbendazim 50 %WP 500 29.99 26.29 27.77 35.90 25.55 26.29 49.65
6 Tebuconazole 25.9 % EC 750 31.11 28.14 28.88 33.33 23.33 24.81 52.48
7 Control -- 33.33 37.02 43.32 -- 48.14 52.21 --
CD@ 5% NS 6.3 5.2 4.53 4.82
CV 15.04 13.49 11.09 11.22

Table 3: Effect of IIL-HEXACARB application of against sheath blight disease on rice during Rabi.

SL. No Treatments Doses (ml or
gm/ ha) Sheath blight PDI Percent disease Control over untreated control
Before Spray Ist Spray Percent disease Control over untreated control IInd Spray
7 days after spray 14 days after spray 7 days after spray 14 days after spray
1 IIL Hexacarb 600 33.33 25.55 27.03 42.53 23.69 23.33 60.62
2 IIL Hexacarb 750 29.99 17.77 16.66 64.58 12.96 12.22 79.38
3 IIL Hexacarb 900 33.33 18.14 18.44 60.79 13.7 14.44 75.63
4 Hexaconazole 5% SC 1000 34.44 26.29 27.77 40.95 24.44 25.18 57.50
5 Carbendazim 50 %WP 500 30.00 27.77 26.66 43.31 23.32 23.7 60.00
6 Tebuconazole 25.9 % EC 750 35.55 27.03 28.14 40.17 24.81 24.43 58.77
7 Control -- 34.44 40.36 47.03 -- 52.58 59.25 --
CD@ 5% NS 5.51 5.3 5.7 5.25
CV 12.43 11.47 13.47 11.86

Table 4: Effect of application of IIL-HEXACARB on paddy yield during Rabi.

SL. No. Treatments Doses
(ml orgm/ ha) Grain Yield (q/ha)
Rabi
1 IIL Hexacarb 600 49.25
2 IIL Hexacarb 750 56.59
3 IIL Hexacarb 900 57.13
4 Hexaconazole 5% SC 1000 43.32
5 Carbendazim 50 % WP 500 48.07
6 Tebuconazole 25.9 % EC 750 46.78
7 Control -- 35.92
CD @ 5% 6.56

Based on the results of the present investigation, it may be concluded that the spraying of the fungicide IIL-HEXACARB found to be excellent against sheath blight and blast diseases of rice and also for the enhancement of the yield of rice over other fungicides and untreated check.
Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto.
,CLAIMS:WE CLAIM:
1) A synergistic fungicidal composition comprising hexaconazole and carbendazim.

2) The synergistic fungicidal composition as claimed in claim 1, wherein weight ratio of hexaconazole and carbendazim is in a range from about 1:1 to 1:10.

3) The synergistic fungicidal composition as claimed in claim 1, wherein the composition comprises hexaconazole in an amount of about 1-10% by weight of the composition and carbendazim in an amount of about 1-20% by weight of the composition.

4) The synergistic fungicidal composition as claimed in claim 3, wherein the composition comprises hexaconazole in an amount of about 4% by weight of the composition and carbendazim in an amount of about 16% by weight of the composition.

5) The synergistic fungicidal composition as claimed in any of the preceding claims, further comprises one or more agriculturally acceptable excipients.

6) The synergistic fungicidal composition as claimed in claim 5, wherein said agriculturally acceptable excipients are selected from the group consisting of a solvent, a surfactant, an emulsifier, a dispersing cum wetting agent, a defoamer, an anti-freezing agent, a thickner, a biocide and a rheology modifier.

7) The synergistic fungicidal composition as claimed in claim 6, wherein said rheology modifier is a silicone ethoxylate.

8) The synergistic fungicidal composition as claimed in claim 7, wherein said silicone ethoxylate is a trisiloxane ethoxylate.

9) The synergistic fungicidal composition as claimed in claim 6, wherein the dispersing agent is a polymeric surfactant based on C9-C15 acrylates as hydrophobe and sulfonic acid group as hydrophilic.

10) The synergistic fungicidal composition as claimed in any of the preceding claims, wherein the composition is formulated as a suspension concentrate (SC), an emulsifiable concentrate (EC), a micro emulsion (ME), an encapsulated suspension (CS), or a water dispersible granule (WG)

11) The synergistic fungicidal composition as claimed in claim 9 is formulated as a suspension concentrate (SC).