Title:
Herbicidal Composition for Field Crops
Field of Invention
The present invention relates to a synergistic herbicidal composition for control of major unwanted vegetation in a wide variety of agricultural crops. More particularly, the present invention relates to a broad spectrum herbicidal composition for controlling broad leaved as well as narrow leaved weeds in sugarcane crop.
Background of Invention
The protection of crops from weeds and other vegetation which inhibit crop growth is a constantly occurring problem in agriculture. To help combat this problem researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical compositions which are effective in the control of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and large number of them is in commercial use. A few examples of commonly used herbicides are Atrazine, Propachor, Chloramben, 2-(2-chloro-4-methanesulfonylbenzoy)-l,3-cyclohexanedione, etc. An advanced herbicidal composition based on a synergistic action is disclosed in a Chinese patent-99114323. The patent claims a weedicide 'Caodashuai' that exhibits broad spectrum weedicidal property at a reduced dosage. While several herbicides/weedicides are available in the market to protect crops, to save labour and improve productivity, there is still a need for new herbicidal with enhanced activity.
Further, there are a few plants for which the weed problem is more severe and complex. The most common example of such a plant is sugarcane, where the weeds tend to flourish extremely well due to abundant water and nutrient supply conditions that are basic requirement for the sugarcane crop. Also, the growth of sugarcane is very slow taking around 100 days from germination till development of full canopy cover. This gives ample time for the weeds to grow in the field. Therefore, a selective herbicide for sugarcane plant can be extremely beneficial to selectively control the target weed without causing any

phytotoxic effects to the sugarcane plant. The existing herbicides in this area do not necessarily meet the requirements of effectiveness and selectivity.
In accordance with the above, there is a need for a selective herbicidal composition for plants that is effective against the target weeds at a very low concentration and exhibit excellent selectivity with minimal or no phytotoxicity.
Summary of the Invention
The main objective of a present invention is to provide a synergistic herbicidal composition which overcomes some or all of the problems associated with the prior art as identified above and others.
Accordingly one of the objectives of our present invention is to provide an herbicidal composition which is highly effective in low dosage amounts.
Another objective of the present invention is to provide an herbicidal composition whose application and effects on the weeds can be directly and visually assessed.
Yet another objective of the present invention is to provide an herbicidal composition which could directly adhere to the surface of the weeds.
Another object of the present invention is to provide an herbicidal composition which is highly effective against broad and narrow leaved weeds in sugarcane crop especially weeds such as Cyprus rotundus along with other Cyprus spp., Digitaria spp., Chenopodium spp. and Melilotus spp.
The other objectives and preferred embodiments and advantages of the present invention will become more apparent from the following description of the present invention when read in conjunction with the accompanying examples which are not intended to limit the scope of the present invention in any manner.
Detailed Description of Invention
An herbicidal composition is provided in accordance with the present invention which is highly effective and efficient against weeds like Cyprus rotundus along with other Cyprus

spp., Digitaria spp., Chenopodium spp. and Melilotus spp., etc.The composition is especially effective against the weeds of sugarcane (SaccharumOfficinarum).
The composition of the present invention is unique and unidentified combination of two different herbicidal components. It exhibits synergistic properties and provides a highly effective and efficient solution for controlling undesired vegetation.
The combination of two existing and identified herbicides to constitute the present composition is based in the premise that, when chemically active ingredients/components are individually known and used as an active herbicide or mixtures thereof it sometimes, depicts a significantly greater effect than was to be expected from a mere cumulative addition of the individual actions. Such an increase in action is termed as synergism and is albeit not a very common phenomenon. Notably the phenomenon is workable only in certain conditions viz. It is possible that the mixture of two or more such active components may not show synergism when mixed in a certain proportion or when prepared in a certain manner, while may still show synergistic effect when mixed in some suitable proportion and/or employing a different mode of preparation.
The herbicides of the present invention when used together in herbicidally effective amount, the resulting mixture has a significantly higher herbicidal activity at a much lower concentration than when either compound was used individually i.e., an excellent synergistic effect is identified. Thus clearly the effect of this combination composition is much more than the cumulative effect of the individual component. Further, the homogenous composition prepared in accordance with the present invention shows no phytotoxic effects on crops.
Furthermore, since the dose of individual components in this composition is less than the requisite doses of individual components for the same effect, the residue in the soil as well in crop is also lower than their individual residues, thereby minimizing any possible side/adverse effects. So this combination is environmentally safer than its parental compounds. Individually in such relatively low concentrations, both the components of the

composition are very safe to nature as well as non-target organisms including human beings.
The combined mode of action of the herbicidal composition in accordance with the present invention also tends to limit the development of resistance in the target population due to minimal use of composition (since the excessive use of herbicides is one of the prime reasons of development of resistance against the particular set of compounds). Thus, with the present composition it is possible to achieve a high herbicidal effect whilst using lower composition is highly economical and effective.
The enhanced and more effective weed control solution minimizes the losses (primarily of nutrients and resources) caused due to weeds and therefore ensures a significant increase in the overall yield of the crop.
The present composition is essentially comprised of two components having individual herbicidal properties with different mode of action- one belongs to the sulfonylurea class whereas other one belongs to the triazinone family of compounds. The components when mixed in herbicidally effective amounts, shows high synergistic effects irrespective of their proportion in the final composition and the mode of preparation of the composition. Accordingly in the final composition of the present invention, each component of the composition is found to significantly enhance and abet the activity of other component and as a single composition are highly effective in overcoming the drawbacks of the prior art. This way the combination not only exhibits an enhanced and more efficient control of weeds (high mortality rate of weeds at low dosage) but also shows long lasting impact upon a diversified target population ofweeds, especially in the sugarcane crop.
In accordance with the present invention, both the components of the composition are systemic herbicides with different mode of action. The individual components, with their potential mode of action, are identified as below.
a) The first ingredient belonging to the sulfonylurea chemical class of compounds is Halosulfuron methyl[Methyl-3-chloro-5-(4,6-dimethoxypyrimidin-2-

ylcarbamoylsulfamoyl)-l-methyl=pyrazole-4-carboxylate]. Halosulfuron methyl act by inhibiting acetolactate synthase ALS (acetohydroxyacid synthase AHAS) by inhibiting the synthesis of essential amino acids valine, leucine, and isoleucine thus resulting in rapid cessation of cell division and plant growth in both roots and shoots. It is a systemic herbicide, absorbed by the root system and/or leaf surface and translocated to meristem tissues.
b) The second component a member from Triazinone family of compounds is
Metribuzin [4-amino-6-(1,1-dimethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one],
which is selective, systemic in action. It inhibits the photosynthetic activities and disrupts plant growth, ultimately leading to death of target weeds.
Considering the above effects, the combination of these two systemic herbicides with different mode of action is a unique combination and is highly effective in controlling weeds in wide range of crops, particularly weeds in sugarcane crops.
In a preferred embodiment of the present invention, the herbicidal composition is a homogenous mixture of wettable granule composition. The wettable granule composition increases the amount of crop yield significantly which is attributable to its homogeneity. Additionally, the wettable granule composition is very safe to handle in comparison to the other formulations; however, in alternate embodiments, other formulations of the herbicidal composition can be prepared by addition of appropriate adjuvants in appropriate amount, as may be obvious to a person of ordinary skill in the art. The exemplary formulations encompassed within the scope of the present invention are wettable powder, emulsion in water, emulsified concentrate, micro-emulsions, granules for soil application, etc.While the preferred adjuvants for preparation of wettable granules include but not limit to Dispersing Agents like Sodium Naphthalene Sulphonate, LignoSulphonate, etc. ; Suspending Agents like Polyethanoxy ether phosphate ester, etc.; Wetting agents like Sodium lauryl sulphate, etc.; Silicon defoamer, Silica ppt; China clay; etc., a variety of different adjuvants as may be obvious to the person of skilled in the art may be used for preparation of other formulations.

The most preferred embodiment of the invention broadly covers herbicidal composition comprising Halosulfuron methyl and Metribuzin at concentration ranging between 10-15% and 50-60%, respectively.
In another preferred embodiment, the compostion comprises Halosulfuron methyl at a concentration of 12% and Metribuzin at a concentration of 55%.
Similarly, in yet another embodiment, the herbicidal composition can be used with other known or new compositions.
The aforesaid compositions/formulations could be formed by mixing the derivatives of the mentioned individual components such as salts, esters, ethers, polymorphs, metabolites, pure forms, isomers, mixtures of isomers, complexes, etc., either alone or in combinations and the same are included within the scope of the present invention.
The present invention will be further illustrated and established by a set of non-limiting examples, depicting the comparative analysis of the efficacy of the combination of active compounds of the present invention.
Example 1:
The current example sets forth ingredients for the preparation of wettable granular composition comprising 12% Halosulfuron methyl + 55% Metribuzin.
Table 1: Ingredients for 12% Halosulfuron methyl + 55% Metribuzin WG
(Table Removed)
Example 2:
Details of experiment were as follows:
i. Season: Kharif 2012-2013
ii. Location of experimentJeevna, Mansoorpur, Muzaffarnagar
iii. Crop: Sugarcane
iv. Variety: COS-60
v. Plot size: 50 sq meter
vi. Design: RBD
vii. Replication: Three viii. Treatments: 7
ix. Date of Planting: 15/04/2012
x. Application: Post emergence, 45-55 days after planting
xi. Herbicide application method: Measured quantity of the chemical was added to required volume of water @ 375 lit. /Ha for spray. The solution was stirred well before application. Knapsack sprayer fitted with boom alongwith flood jet nozzle was used to apply the herbicidal solution
Treatment details:
(Table Removed)
Evaluation of Bio efficacy:
Weed count: A quadrate (0.5m x 0.5m) was placed at 3 randomly selected places in all the plots of the experimental field and the number of weed flora were counted uniformly at 7, 15 and 30 days after application.
Weed control: The weed control was calculated based on no. of live weed flora at 7,15 and 30 days after application.
(Formula Removed)
Where,
WC= No. of weed in control plot
WT= No. of weed in treated plot
Table-1: Effect of herbicidal treatment on weed density of narrow and broad leaves weedsat 30 DAA
(Table Removed)
Where,
Spp. - Species, Live pop. Live population
DAA - Days after application
Results:
The prominent weed species in the weedy plot at the time of application were Cyperusrotundusfo\lowed byBracaria spp.,Dactylectanium spp. andAmaranthus spp.
-Higher doses of CPL-1255 i.e. 600gm/ha and 900gm/ha showed the maximum control (98.71% and 100% rspectively) against Cyperusrotundus at 30 DAA.
-Application of Halosulfuron methyl 12% + Metribuzin 55% WG combination at the rate of 450gm/ha showed the synergistic effect and gave the best control of weeds (98.28% which was at par with higher doses) over the individual components i.e. Halosulfuron methyl 75%WG and Metribuzin 70%WP against Cyperusrotundusat 30 DAA.
-Same results were observed with Halosulfuron methyl. 12% + Metribuzin 55% WG combination at the rate of 450gm/ha in case of the Amaranthus spp.(broad leaves weed) Dactylectanium spp. andBracaria spp.
-Alone Treatment 5 and Treatment 6 could not control Bracaria spp. while the combination of Halosulfuron methyl 12% + Metribuzin 55% WG gave 67.66% which confirms the synergistic phonemenon of the component of the two herbicides in the present combination.
-Similarly, in case of Dactylectanium spp. the combination showed good efficacy against weed in comparison to alone components confirming the synergistic effect.
From the above, it can be seen that the present composition exhibits synergistic effect even at lower concentrations and is highly effective in controlling weed population in an effective way.
Although the present invention has been described on considerable detail with reference to certain preferred embodiments and examples thereof, other embodiments and equivalents
are possible. Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with functional and procedural details, the disclosure is illustrative only, and changes may be made in detail, especially in terms of the procedural steps within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. Thus various modifications are possible of the presently disclosed process without deviating from the intended scope and spirit of the present invention. More particularly, the method for preparation of the composition, as depicted in the present invention, is seemingly a simplified and generalized one and there are several trivial variations possible.

We Claim:
1. An herbicidal composition comprising synergistically effective amount of two active
ingredients, wherein the first active ingredient is Halosulfuron methyl and the second
active ingredient isMetribuzin.
2. The composition of claim 1, wherein the amount of Halosulfuron methyl ranges from
10-15% w/w and the amount of Metribuzin ranges from 50-60% w/w.
3. The composition of claim 1, wherein the amount of Halosulfuron methyl is about 12%.
4. The composition of claim 1, wherein the amount of Metribuzin is about 55%.

5. A formulation prepared using the composition of claim 1, wherein the formulation comprises of one or more adjuvants.
6. The formulation as claimed in claim 5, wherein the amount of adjuvant/s ranges from about 25% w/w to 40 % w/w.
7. The formulation as claimed in claim 5, wherein the formulation is in the form of
powder, solid or liquid.
8. A method for controlling unwanted vegetation in agricultural crops, where unwanted vegetation includes weed population.