The present invention relates to the field of agrochemicals. In particular, the present invention relates to an herbicidal combination, a composition comprising the combination and its application.
BACKGROUND OF THE INVENTION
Rice (oryza sativa L.) is one of the important food grains of India and its production is about 40% of total food grain production. It plays an important role in the food security and livelihood for every household. In spite of being the second largest rice producing country in the world after China, the production of rice in India is mainly affected by weeds present in the paddy crop. Weeds often compete with the crop for sunlight, water and other nutrients and thus reduce the yield and deteriorate the quality of the crop. Further, weeds act as a host for pests and other plant diseases and sometimes contaminate water in the surrounding field and eventually affect the growth, quality and yield of paddy crop. Therefore, effective management of weeds in paddy crop is imperative to maintain crop yield and to ensure the food security for the growing population.
There are few prior art documents wherein herbicidal combination comprising two or more herbicides for the management of weeds in crop plants are disclosed and are elaborated herein below.
553/MUM/2002 discloses a process for preparing synergistic herbicidal composition useful for the control of weeds comprising Pyrazosulfuron ethyl in an amount ranging from 0.01 to 5.0% by weight of the composition, and another selected herbicide(s) namely Butachlor, Pretilachlor or 2,4-Dichlorophenoxy acetic acid (2,4- D) in an amount ranging from 1 to 50 % by weight of the composition along with conventional agriculturally accepted carrier(s) and excipient(s) in an amount ranging from 45 to 98.9 % by weight. The disclosed compositions are highly effective for the protection of growing plants including: cotton, paddy, rice forage crops, sugarcane, cole crops, leafy vegetables, tobacco, tomatoes, potatoes, flowering ornamentals, vine crops and fruit trees from the ravages of insects.
GB201321409A discloses a herbicidal composition comprising a 4-(substituted biphenyl-3-yl)-2H-pyran-3,5(4H, 6H)-dione and an ALS (acetolactate synthase) inhibitor herbicide suitable for use on rice, wherein the rice-suitable ALS inhibitor herbicide is bensulfuron-methyl, pyrazosulfuron-ethyl, azimsulfuron, flucetosulfuron, orthosulfamuron, prosulfuron, triasulfuron, trifloxysulfuron, bispyribac, pyriminobac-methyl, pyribenzoxim, and/or penoxsulam, or an agriculturally acceptable salt and a safener and a method for controlling grassy weeds for example Brachiaria, Echinochloa and/or Leptochloa in crops of useful plants such as rice.
US9930889B2 relates to a method of controlling undesirable vegetation in rice which comprises applying a synergistically herbicidal combination comprising an effective amount of (a) penoxsulam, or an agriculturally acceptable salt thereof, and (b) mefenacet, or an agriculturally acceptable salt thereof, to the undesirable vegetation or an area adjacent the vegetation, or applying to soil or water to control the emergence or growth of the undesirable vegetation. It was also mentioned that the disclosed combination further comprised of additional pesticide includes one or more pesticides selected from the group consisting of cyhalofop-butyl, bensulfuron-methyl, bentazon-sodium, benzobicyclon, bromobutide, fenoxaprop-ethyl, halosulfuron-methyl, metamifop, metazosulfuron, metsulfuron-methyl, profoxydim, pyrazosulfuron-ethyl, triafamone and combinations thereof.
CN1894220B disclosed an herbicidal composition comprising pyrimidine-based compound of formula I, an effective amount of additional herbicides and herbicide safener along with excipients useful for controlling undesired vegetation.
Certain other compositions are also disclosed such as metsulfuron methyl+chlorimuron ethyl (Kaur et al, Agric Res J, 54 (3), 2014, pages 329-334), Clodinafop-propargil+Metribuzin, Pinoxaden+ Sulfosulfuron and Sulfosulfuron + Clodinafop-propargil (Abbas et al (Planta Daninha, Vicosa-MG, vol. 34 (4), 2016, pages 787-793), Bis-pyribac-sodium+ethoxysulfuron, Bis-pyribac-sodium+chlorimuron ethyl+metsulfuron-methyl, Pretilachlor+ethoxysulfuron, Pretilachlor+chlorimuron ethyl+metsulfuron-methyl and Pretilachlor+bensulfuron (Priyanka et al (Indian Journal of Weed Science, 46(4), 2014, pages 377-379), cyhalofop butyl + bensulfuron methyl (Rahamn et al), penoxsulam+cyhalofop butyl (Lap et al. 2013 and Abraham and Menon, 2015) and bispyridac sodium+metamifop for the management of unwanted weeds and for improving the yield of paddy and wheat crop. However, the prior art documents suffer from either one or more of the following disadvantages:
• Use of expensive herbicide components or component;
• High dosage of herbicide components and thus possible environmental hazard;
• Phytotoxicity problem when used in higher doses and thus reduced crop yield;
• Selective on controlling either grassy weeds or sedges or broad-leaf weeds but less effective/no effective in controlling all of them together;
• Incompatibility in synthesis or mixing of the components.

Therefore, there is a need to provide a synergistic herbicides combination, which are chemically compatible, affordable and which can control the weeds including grassy weeds, sedges and broad-leaf weeds present in the paddy field to improve the growth and grain yield without resulting in any environmental hazard and phytotoxicity.
Object of the Present Invention
An object of the present invention is to provide a novel and synergistic herbicidal combination for controlling weed, sedges, broad-leaf weeds (BLW’s) and a composition comprising the same and its utility in improving the yield of food crop.
Summary of the Present Invention
The present invention provides a novel synergistic combination comprising a first herbicide and a second herbicide both belonging to the same class of sulfonylureas. The present application further provides an herbicidal composition comprising the said synergistic combination along with agriculturally acceptable excipient. The present application further discloses the bio-efficacy effect of the disclosed combination in controlling weeds, sedges and BLW’s in a paddy crop, the phytotoxic effect of the disclosed combination on paddy and effect of the disclosed combination on growth and yield of paddy crop.
Detailed Description of the Present Invention
Rice is one of the important food grains in India and other South Asian countries. It plays an important role in the food security and livelihood for almost every household. But, the production of rice is always affected by the presence of weeds because these weeds compete with the paddy crop for the nutrients, water and sunlight. Further, the paddy crop is infested by several grassy and broad leaves weeds and eventually causes an extensive damage to the paddy crop. Therefore, there is an urge for the effective control of weeds including grassy weeds, sedges and broad-leaf weeds (BLW’s) in a paddy crop in order to enhance crop productivity and thereby ensuring the food security.
The present invention provides a novel and synergistic combination comprising a first herbicide and a second herbicide both belonging to the same class of sulfonylurea.
Without being limited by theory, the present invention discloses that combination of two herbicides from the same class is synergistic, enhances the efficacy of the herbicides, reduces the dose of the individual herbicides and demonstrates reduced toxicity. Further, the said combination of the present invention effectively controls grassy weeds, sedges and broad-leaf weeds (BLW’s) in paddy crop and increases the growth and yield of the paddy crop.
The first sulfonyl urea herbicide may be selected from the group consisting of amidosulfuron, azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethametsulfuron-methyl, cinosulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron-methyl-sodium, imazosulfuron, metsulfuron-methyl, nicosulfuron, oxasulfuron, primisulfuron-methyl, prosulfuron, pyrazosulfuron-ethyl, rimsulfuron, sulfometuron-methyl, sulfosulfuron, thifensulfuron-methyl, triasulfuron, tribenuron-methyl, and triflusulfuron-methyl.
The present invention envisages, that the first sulfonyl urea herbicide may preferably be pyrazosulfuron-ethyl and the second herbicide may be any other sulfonyl urea herbicide.
The second herbicide of the present invention may be selected from the group consisting of amidosulfuron, azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethametsulfuron-methyl, cinosulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron-methyl-sodium, imazosulfuron, metsulfuron-methyl, nicosulfuron, oxasulfuron, primisulfuron-methyl, prosulfuron, rimsulfuron, sulfometuron-methyl, sulfosulfuron, thifensulfuron-methyl, triasulfuron, tribenuron-methyl, and triflusulfuron-methyl, preferably the second herbicide is chlorimuron-ethyl or sulfosulfuron.
The present invention describes a novel and synergistic combination comprising first herbicide and second herbicide both belonging to the same class of sulfonylurea herbicide wherein the first herbicide is present in the ratio of 99-1% by weight, preferably 30 to 1% and the second herbicide is present in the ratio of 1-99% by weight, preferably 1-50% by weight. Preferably the combination comprises pyrazosulfuron-ethyl in the ratio of 30 to 1% by weight, more preferably 10 to 5% by weight and sulfosulfuron or chlorimuron in the ratio of 1 to 50 % by weight, preferably 15-50% by weight.
The preferred synergistic combination of the present invention is pyrazosulfuron-ethyl 10% +Sulfosulfuron 50% WP or pyrazosulfuron-ethyl 5%+chlorimuron-ethyl 15% EC.
The present invention discloses a novel and synergistic combination comprising first herbicide and second herbicide both belonging to the same class of sulfonylurea herbicide wherein the herbicides may be present in the ratio of 1:3 to 1:5.
In another embodiment, the present application also provides a synergistic composition comprising the above-mentioned combination along with agriculturally acceptable excipients.
The agriculturally acceptable excipients of the present invention may be selected from the group consisting of a stabilizer, a disintegrating agent, an antifoaming agent, a wetting agent, a dispersing agent, binding agent, an emulsifying agent and water.
The synergistic herbicidal composition of the present invention may be formulated in a suitable composition selected from for example solid and liquid composition preferably in the form of emulsifying concentrates, wet dispersible powder and wet dispersible granules etc.
In another embodiment, the synergistic combination and the composition comprising the synergistic combination are effective in controlling the grassy weeds, sedges and broad-leaf weeds (BLW’s) mainly Echinochloa spp., Dctyloctenium aegypticum and Eleusine Indica in the agricultural field, particularly in a paddy crop as compared to untreated control.
The synergistic herbicidal combination or the composition of the present invention is superior on reducing the count or population of grassy weeds, sedges and broad-leaf weeds (BLW’s) mainly Echinochloa spp., Dctyloctenium aegypticum and Eleusine Indica at 15, 30, 45 and 60 days after application as compared to the individual herbicide pyrazosulfuron-ethyl or sulfosulfuron available in the market (Table 2-5). The growth and yield of paddy crop is also improved and almost equivalent to the growth and yield obtained with weed free control (Table 6). The disclosed combination further showed no phytotoxicity in the paddy crop even after 30 days after spraying (Table 7).
The Application is drawn to a chemical product, which is tested in fields and does not claim or utilise any indigenous natural biological material and therefore NBA does not apply.
The present invention is illustrated by way of examples, the examples are meant for illustrative purposes and should not be construed as limiting.
Example 1: Preparation and Application of Different doses of combination of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50%WP
A field experiment was conducted during Kharif season in 2018 at Indogulf Cropsciences Research and Development Farm, Nathupur, Sonepat (Haryana) to evaluate the bioefficacy and phototoxicity of different doses of combination of pyrazosulfuron-ethyl and sulfosulfuron, particularly different doses of combination of pyrazosulfuron-ethyl 10% WP + Sulfosulfuron 50% WP as post emergence herbicide along with standard product Pyrazosulfuron-ethyl 10% WP and Sulfosulfuron 75% WP in paddy crop as shown in Table 1.
The experiment was conducted in a simple Randomized Block Design with eight treatments (Table 1) and three replications using Paddy var. Pusa-1509 in a plot of 5x5 m2 size. The crop was sown on 8th June 2018 in nursery and transplanted to main field on 9th July 2018. As per protocol of the Indogulf Cropsciences Limited, one spray of different doses of Pyrazosulfuron-ethyl 10% + Sulfosulfuron 50% WP on 29th July 2018 (20 DAT) was carried out with knapsack sprayer using flat fan nozzle @ 500 litres water/ha.
Table 1: Preparation and application of different doses of combination of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP
S.No. Treatments Doses
(g a.i./ha) Formulated product (ml/ha) Time of application
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 50.0 20 DAT
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 75.0 20 DAT
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 100.0 20 DAT
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 150.0 20 DAT
5* Pyrazosulfuron-ethyl + Sulfosulfuron 20.0+100.0 200.0 20 DAT
6 Pyrazosulfuron ethyl 10%WP (Market sample) 15.0 150 10DAT
7 Sulfosulfuron 75%WP 25.0 33.3 20 DAT
8 Weed free control 2-3 hand weeding - 15 & 30 DAT
9 Untreated control
• Only for Phytotoxicity study
Number of Applications: One
Spray Volume: 500 litre/ha
Method of application: Post emergent application using knapsack sprayer fitted with flat fan nozzle
Time of application : At 3-4 leaf stage of weed at 14-21 Days after transplanting (DAT)

Example 2: Evaluation of bioefficacy of the present herbicidal combination on weed control (WCE)
Most dominant weeds of the experimental field were Echinocloa crusgalli, Digeria arvensis, Fimbristylis miliacea, Dctyloctenium aegypticum, Elusine indicum Ludwigia parviflora, Monochoria vaginalis, Trianthema spp.,and Cyperus rotundus. Other weeds viz. Phyllanthus niruri, Commelina bengalensis, Cynodon dactylon, Sataria Spp. Digitaria etc were also observed as minor weeds in Paddy crop.
Species wise weed count were recorded before application and at 15 days interval after imposition of treatments up to 60 days using quadrates of 0.5x 0.5m. Similarly, the weed dry matter was recorded by uprooting and drying. The data on weed density was analyzed after subjecting the original data to Square Root Transformation. The crop was harvested on 13th October 2018 and yield per hectare was calculated after multiplying the yield per plot with hectare factor. The weed control efficiency (WCE) was worked out as under:
Dry wt. of weeds under control plot- Dry wt. of weeds under treatment
WCE = ------------------------------------------------------------------------------------- X 100
Dry weight of weeds under control plot

The results of observations on bioefficacy of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50%WP for controlling weeds in Paddy crop are presented in Tables 2 to 5.

Table 2a: Bioefficacy of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP against weeds in Paddy crop after 15 days of application
S. No. Treatments Dose (g a.i./ha) Grasses Sedges Broad leaved weeds
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 18.13 12.10 72.72 8.17 2.47 72.21 2.67 1.94 85.82
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 18.02 12.01 72.93 7.24 2.10 76.37 2.11 1.57 88.52
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 16.14 11.52 74.03 6.67 2.03 77.16 2.17 1.17 91.44
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 14.50 11.12 74.93 5.17 1.11 87.51 1.83 1.05 92.32
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 20.33 13.38 69.84 12.83 3.24 63.55 13.50 7.61 44.37
6 Sulfosulfuron75%WP (Market sample) 25.0 19.50 12.42 72.01 18.67 6.74 24.18 18.33 10.99 19.66
7 Weed free control 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
Untreated control 29.00 44.37 20.33 8.89 21.50 13.68
SE 0.11 0.56 0.18 0.42 0.18 0.54
C.D. at 5% 0.35 1.73 0.54 1.29 0.54 1.68

Table 2b: Effect of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP on major grassy weeds in Paddy crop after 15 days of application
S. No. Treatments Dose (g a.i./ha) Echinochloa spp. Dctyloctenium aegypticum Eleusine indica
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 7.01 2.03 92.49 6.67 2.72 85.23 5.11 2.47 85.95
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 6.67 1.95 92.78 6.00 2.64 85.66 4.17 2.22 87.37
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 4.50 1.52 94.37 4.83 2.33 87.35 3.11 1.85 89.48
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 4.17 1.10 95.93 4.17 2.17 88.21 2.72 1.74 90.10
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 15.83 11.69 66.76 15.50 12.48 32.24 13.78 12.03 31.60
6 Sulfosulfuron
75%WP (Market sample) 25.0 15.17 11.47 57.58 14.83 12.33 33.06 13.44 11.95 32.06
7 Weed free control 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
8 Untreated control 21.17 27.04 19.33 18.42 7.89 7.59
SE 0.07 0.46 0.09 0.26 0.10 0.14
C.D. at 5% 0.23 1.43 0.27 0.80 0.30 0.45
* Mean of three replications

Table 3a: Bioefficacy of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP against weeds in Paddy crop after 30 days of application
S. No. Treatments Dose (g a.i./ha) Grasses Sedges Broad leaved weeds
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 24.33 14.87 74.40 6.12 1.73 91.45 2.40 2.20 91.82
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 23.67 14.41 75.20 5.83 1.69 91.35 2.33 2.11 92.15
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 17.83 12.47 78.53 5.83 1.64 91.61 2.13 2.10 92.19
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 15.50 11.61 80.01 4.67 1.62 91.71 1.10 1.51 94.38
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 24.50 16.69 71.27 13.83 3.67 81.22 10.17 12.26 54.42
6 Sulfosulfuron75%WP (Market sample) 25.0 23.50 15.08 74.04 15.17 7.69 60.65 16.67 18.36 31.74
7 Weed free control 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
8 Untreated control 34.17 58.10 26.83 19.55 27.50 26.90
SE 0.15 2.34 0.22 1.05 0.17 1.04
C.D. at 5% 0.47 7.20 0.69 3.24 0.53 3.20

Table 3b: Effect of Pyrazosulfuron-ethyl + Sulfosulfuron on major grassy weeds in Paddy crop after 30 days of application
S. No. Treatments Dose (g a.i./ha) Echinochloa spp. Dctyloctenium aegypticum Eleusine indica
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 8.91 4.90 81.76 7.01 4.19 83.95 4.92 3.67 84.05
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 8.67 4.88 81.83 6.83 4.13 84.18 4.83 3.60 84.36
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 6.17 3.83 85.74 5.83 3.08 88.20 3.83 2.76 88.01
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 5.50 3.11 88.42 5.17 2.36 90.96 3.17 2.18 90.52
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 17.83 14.25 46.96 16.17 13.50 48.31 14.67 13.10 43.09
6 Sulfosulfuron75%WP (Market sample) 25.0 16.83 14.03 47.78 15.00 13.28 49.15 14.33 12.92 43.87
7 Weed free control 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
8 Untreated control 26.00 26.87 20.83 26.12 18.83 23.02
SE 0.08 0.49 0.09 0.55 0.11 0.26
C.D. at 5% 0.25 1.50 0.26 1.69 0.33 0.79
* Mean of three replications,
Table 4a: Bioefficacy of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50%WP against weeds in Paddy crop after 45 days of application
S. No. Treatments Dose (g a.i./ha) Grasses Sedges Broad leaved weeds
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 27.33 20.75 73.65 8.67 3.14 93.15 3.69 1.79 95.62
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 26.00 20.44 74.04 8.50 3.01 93.44 3.67 1.51 96.30
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 25.00 19.83 74.82 7.50 2.41 94.74 3.17 1.37 96.64
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 21.67 18.39 76.65 7.50 2.23 95.14 3.00 1.33 96.74
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 27.67 22.82 71.02 12.17 16.24 64.61 8.19 8.10 80.18
6 Sulfosulfuron75%WP (Market sample) 25.0 26.33 22.60 71.31 18.00 11.71 81.02 20.50 11.28 72.39
7 Weed free control 2 weeding 5.67 6.74 91.44 8.00 11.30 75.39 6.33 8.27 79.77
8 Untreated control 49.33 78.76 36.67 45.90 41.67 40.87
SE 0.23 1.69 0.09 2.10 0.18 1.94
C.D. at 5% 0.71 5.22 0.28 6.49 0.55 5.97

Table 4b: Effect of Pyrazosulfuron-ethyl + Sulfosulfuron on major grassy weeds in Paddy crop after 45 days of application
Sr No. Treatments Dose (g a.i./ha) Echinochloa spp. Dctyloctenium aegypticum Eleusine indica
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 11.67 8.67 71.77 9.00 7.10 79.84 6.69 7.01 73.81
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 10.33 8.33 72.88 8.67 6.83 80.60 6.50 6.06 77.36
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 7.83 7.39 75.94 7.17 5.89 83.27 5.17 5.31 80.16
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 6.83 6.97 77.31 6.50 5.47 84.46 4.50 4.98 81.39
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 19.33 17.72 42.31 18.50 16.22 53.94 16.00 15.57 41.83
6 Sulfosulfuron75%WP (Market sample) 25.0 17.83 17.70 42.38 16.50 16.20 54.00 15.50 15.56 41.87
7 Weed free control 2 weeding 1.50 2.33 92.41 1.17 0.83 97.64 1.50 1.26 95.29
8 Untreated control 28.83 30.72 24.50 35.22 22.33 26.77
SE 0.15 0.94 0.12 0.94 0.13 0.75
C.D. at 5% 0.46 2.89 0.38 2.89 0.40 2.31
* Mean of three replications,
Table 5a: Bioefficacy of Pyrazosulfuron-ethyl + Sulfosulfuron against weeds in Paddy crop after 60 days of application
S. No. Treatments Dose (g a.i./ha) Grasses Sedges Broad leaved weeds
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 33.01 27.19 74.58 7.12 3.21 93.46 3.79 2.02 96.24
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 32.33 26.03 75.67 6.00 3.03 93.83 3.33 1.89 96.48
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 28.00 25.83 75.85 5.00 2.81 94.27 3.33 1.81 96.63
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 25.33 25.39 76.27 5.67 2.32 95.27 3.33 1.47 97.26
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 31.17 30.43 71.56 16.50 2.01 59.25 10.50 7.40 86.24
6 Sulfosulfuron75%WP (Market sample) 25.0 27.00 28.27 73.58 19.50 21.34 56.56 22.50 14.04 73.89
7 Weed free control 2 weeding 7.83 18.23 82.96 10.50 13.83 71.84 7.83 13.99 73.99
8 Untreated control 48.67 107.00 41.67 49.11 43.67 53.78
SE 0.17 1.15 0.14 1.65 0.21 2.19
C.D. at 5% 0.51 3.56 0.42 5.09 0.64 6.74

Table 5b: Effect of Pyrazosulfuron-ethyl + Sulfosulfuron on major grassy weeds in Paddy crop after 60 days of application
S. No. Treatments Dose (g a.i./ha) Echinochloa spp. Dctyloctenium aegypticum Eleusine indica
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 11.33 10.69 74.54 9.33 8.93 80.37 7.30 7.82 76.43
2 Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 10.67 10.37 75.30 9.17 8.88 80.48 7.00 7.70 76.80
3 Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 8.83 9.53 77.30 7.17 7.92 82.59 5.50 6.92 79.15
4 Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 7.83 9.06 78.42 6.17 7.46 83.60 5.17 6.55 80.26
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 20.17 20.12 52.08 18.50 18.49 59.37 17.00 17.37 47.66
6 Sulfosulfuron75%WP (Market sample) 25.0 19.17 19.35 53.91 17.67 17.69 61.12 15.83 16.73 49.59
7 Weed free control 2 weeding 2.50 4.88 88.37 1.50 3.40 92.52 1.83 3.32 89.99
8 Untreated control 26.83 41.99 25.67 45.51 23.50 33.19
SE 0.16 0.52 0.15 0.50 0.12 0.45
C.D. at 5% 0.48 1.59 0.45 1.53 0.36 1.39
* Mean of three replications,
From the tables above it can be seen that a significant reduction in grassy weeds, sedges and broad leaf weeds is recorded with Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50% WP @ 45.0 g. a.i./ha (treatment 2) at 15, 30, 45 and 60 days after application. The reduction in the grasses, sedges and broad leaf weeds were statistically superior in comparison with its standard alone treatment viz., Pyrazosulfuron10%WP, Sulfosulfuron 75%WP and untreated control. Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50% WP @ 45.0 g. a.i./ha (treatment 2) and its above dosages (treatment 3 and 4) were superior as compare to its market sample of Pyrazosulfuron-ethyl 10% @15.0 g. a.i. and Sulfosulfuron75%WP @25 g. a.i./ha.
Among weed control treatments, Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50%WP @ 90.0 g. a.i./hectare (treatment 4) resulted in significantly lowest count of Echinochloa spp., Fimbristylis miliacea and Monochoria vaginalis at 15 to 60 days after application (Table 2-5). The results of treatments on weed control indicates that the recommended dose of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP @ 45.0 g a.i./ha (treatment 2) is statistically on par with its above dosages and superior from market sample Pyrazosulfuron-ethyl 10% and Sulfosulfuron 75%WP (treatment 5 and 6) in reducing the population of grassy weeds, sedges and broad leaf weeds. It was also found that maximum percent weed control was recorded in Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP @ 90.0 g. a.i./ha (76.65 – 96.74 %) (treatment 4) at 45 days after application.
Example 3: Effect of the synergistic herbicidal combination of Pyrazosulfuron-ethyl+ Sulfosulfuron on yield of the paddy crop
The effect of the disclosed synergistic herbicidal combination of Pyrazosulfuron-ethyl+ Sulfosulfuron on yield of the paddy crop is also studied. A significantly higher yield was observed under all the treatments as compared to the untreated check. A maximum seed yield of 51.72 q/ha is obtained with Pyrazosulfuron-ethyl 10% WP + Sulfosulfuron 50% WP @90.0 g a.i/hectare (treatment 4) which is at par with weed free check (treatment 7) and its lower dosages i.e. 60.0 and 45.0 a.i/hectare (treatments 2-3) as shown in Table 6. The combination involves sulfosulfuron 50% WP in reduced concentration as compared to the commercial sulfosulfuron 75% WP and in turn results in reduced toxicity to the crop, soil ad environment.
Table 6: Effect of Pyrazosulfuron-ethyl 10%+ Sulfosulfuron50%WP application on yield and yield attributing characters of Paddy crop
S. No Treatments
Doses (g a. i./ha) Plant Height (cm) days after application No of tillers / hill Av. panicle length (cm) Test wt. (g) Grain yield (q/ha) Straw Yield
(q/ha)
15 30 45 60
1. Pyrazosulfuron-ethyl + Sulfosulfuron 5.0+30.0 23.67 61.67 102.38 109.12 23.65 15.72 11.48 48.89 39.18
2. Pyrazosulfuron-ethyl + Sulfosulfuron 7.5+37.5 23.67 61.00 101.88 110.67 23.73 15.80 11.47 49.12 40.40
3. Pyrazosulfuron-ethyl + Sulfosulfuron 10.0+50.0 25.17 62.44 102.50 113.17 24.80 16.20 12.43 50.10 40.49
4. Pyrazosulfuron-ethyl + Sulfosulfuron 15.0+75.0 25.30 63.03 103.00 113.42 25.07 16.47 12.50 51.72 40.79
5 Pyrazosulfuron-ethyl 10%WP (Market sample) 15.0 23.03 59.01 94.32 108.92 18.20 15.27 11.62 45.21 38.86
6 Sulfosulfuron75%WP (Market sample) 25.0 24.00 58.10 95.25 108.77 19.67 14.87 12.15 46.02 39.46
7 Weed free control (hand weeding) 2 23.67 65.67 103.00 114.33 25.13 14.27 12.59 51.83 41.60
8 Untreated control - 22.33 55.89 90.50 105.33 11.33 14.60 11.40 27.02 26.83
SE 0.68 3.05 3.22 1.72 0.55 0.68 0.60 0.88 1.46
C.D. at 5% NS NS 9.92 5.29 1.68 2.08 NS 2.72 4.49

Example 4: Phototoxicity effect of the synergistic herbicidal combination of Pyrazosulfuron-ethyl + Sulfosulfuron on paddy crop
After spraying, the paddy crop was continuously monitored for all phytotoxicity symptoms including temporary or longer lasting damage caused to plants if any, leaf injury on tips and leaf surface, wilting, vein clearing, Necrosis, Epinasty, Hyponasty, plant height. The crop health was also observed based on visual rating from 1-10 as given below:
Rating Crop Injury % Verbal description
0 -- No symptoms
1 1-10 Very slight discoloration
2 11-20 More severe, but not lasting
3 21-30 Moderate and more lasting
4 31-40 Medium and lasting
5 41-50 Moderately heavy
6 51-60 Heavy
7 61-70 Very Heavy
8 71-80 Nearly destroyed
9 81-90 Destroyed
10 91-100 Completely destroyed

It was found that the synergistic combination of Pyrazosulfuron-ethyl 10% + Sulfosulfuron 50% WP at 50.0 g a.i/ha (treatment 1) showed no phytotoxicity effect (rating 0) on paddy crop and even at the higher doses of 200 g a.i/ha (treatment 5) the combination is safe on the paddy crop as shown in Table 7.
Table 7: Phytotoxicity studies of Pyrazosulfuron-ethyl 10% + Sulfosulfuron 50%WP on Paddy crop
S. No. Treatment Dose (g/ha) Phytotoxicity ratings after spray*
1 DAS 3 DAS 5 DAS 7 DAS 10 DAS 15 DAS 30 DAS
1. Pyrazosulfuron-ethyl + Sulfosulfuron 50.0 0 0 0 0 0 0 0
2. Pyrazosulfuron-ethyl + Sulfosulfuron 75.0 0 0 0 0 0 0 0
3. Pyrazosulfuron-ethyl + Sulfosulfuron 100.0 0 0 0 0 0 0 0
4. Pyrazosulfuron-ethyl + Sulfosulfuron 150.0 0 0 0 0 0 0 0
5. Pyrazosulfuron-ethyl + Sulfosulfuron 200.0 0 0 0 0 0 0 0
6. Untreated control - 0 0 0 0 0 0 0
*Mean of three replications
Note: Phytotoxicity symptoms were observed on various parameters such as leaf injury, wilting, yellowing, epinasty etc. as mentioned in methodology as per CIB guidelines

Example 5: Evaluation of the efficacy of Chlorimuron Ethyl 15%+ Pyrazosulfuron 5%EC
The Bio-efficacy of herbicidal combination of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5% EC in controlling grassy weeds, sedges and BLW’s in Rice variety of Pusa 1509, (Post-emergence, 2-6 leaf stage of weeds) is also studied. The effect of the combination on phytotoxicity and growth and yield of Paddy crop is also monitored,
Table 8: Treatments Applied in the field
S.No. Treatments Doses
(g a.i./ha) Formulated product (ml/ha) Time of application
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 10.0+4.0 40.0 18 DAT
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 12.5+5.0 50.0 18 DAT
3 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 15.0+6.0 60.0 18 DAT
4* Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 20.0+8.0 80.0 18 DAT
5 Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP (market sample) 4.0 20.0 3 DAT
6 Pyrazosulfuron ethyl 10%WP (Market sample) 15.0 150 10DAT
7 Chlorimuron Ethyl 25%WP (market sample) 6.0 24.0 18 DAT
8 Weed free control 2-3 hand weeding - 15 & 30 DAT
9 Untreated control
*Only for Phytotoxicity study. Number of Applications: One, Spray Volume: 500 lt/ha, Method of application: Post emergent application using knapsack sprayer fitted with flat fan nozzle, Time of application : At 3-4 leaf stage of weed at 14-21 Days after transplanting (DAT)

Observations were as below:
* Species wise weed count - before application, 1, 15, 30, 45, & 60 DAA
* Weed dry matter and growth parameters at 15, 30, 45, &60 DAA
* Yield and harvest index
* Phytotoxicity at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 DAA

A field experiment was conducted during Kharif 2019 to evaluate the bio-efficacy and phytotoxicity of different doses of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC as post emergence herbicide along with standard product Pyrazosulfuron-ethyl 10% WP, Chlorimuron ethyl 25%WP and Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP in Paddy crop. The experiment was conducted in a simple Randomized Block Design with eight treatments and three replications using Paddy variety i.e. Pusa-1509 in a plot of 5x5 m2 size. The crop was sown on 8th June, 2019 in nursery and transplanted to main field on 9th July 2019. As per protocol Indogulf Cropsciences Ltd one spray of different dosages of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC on 27th July, 2019 (18 DAT) was carried out with knapsack sprayer using flat fan nozzle @ 500 litres water/ha.

Species wise weed counts were recorded before application and at 15 days interval after imposition of treatments up to 60 days using quadrates of 0.5x 0.5m. Similarly, the weed dry matter was recorded by uprooting and drying. The data on weed density was analysed after subjecting the original data to Square Root Transformation. The crop was harvested on 14rd Oct, 2019 and yield per hectare was calculated after multiplying the yield per plot with hectare factor. The weed control efficiency (WCE) was worked out as under:

Dry wt. of weeds under control plot- Dry wt. of weeds under treatment
WCE = --------------------------------------------------------------------------------------- X 100
Dry weight of weeds under control plot

For phytotoxicity evaluation on Paddy crop following observations were recorded on temporary or longer lasting damage caused to plants if any, Leaf Injury on tips and leaf surface, Wilting, Vein clearing, Necrosis, Epinasty, Hyponasty, Plant Height.

Table 9 : Crop injury was observed on visual rating from 1-10 as given below:
Rating Crop Injury % Verbal description
0 -- No symptoms
1 1-10 Very slight discoloration
2 11-20 More severe, but not lasting
3 21-30 Moderate and more lasting
4 31-40 Medium and lasting
5 41-50 Moderately heavy
6 51-60 Heavy
7 61-70 Very Heavy
8 71-80 Nearly destroyed
9 81-90 Destroyed
10 91-100 Completely destroyed

The most dominant weeds of the experimental field were Echinocloa crusgalli, Fimbristylis miliacea, Cyperus deformis, Eclipta alba, Digeria arvensis, Eleusine indica, Dctyloctenium aegypticum and Trianthema spp., Other weeds viz. Phyllanthus niruri, Commelina bengalensis, Cynodon dactylon, Sataria Spp. Digitaria etc were observed as minor weeds in Paddy crop. The results of observations on bioefficacy of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5% EC for controlling weeds in Paddy crop are presented in Tables 10 to 14. It is revealed that a significant reduction in grassy and broad leaf weeds was recorded with Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 17.5 g. a.i./ha at 15 and 30 days after application. It was however, at par with Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 14.0 g a.i./ha and market sample of Chlorimuron Ethyl 10%+ Metsulfuron Methyl 10%WP @ 4.0 g a.i./ha. Among weed control treatments, Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 21.0 g. a.i./ha resulted in significantly lowest count of Echinochloa spp., Cyperus deformis and Fimbristylis miliacea at 15 to 30 days after application (Table 10-14). It was also found that Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 21.0 g. a.i./ha recorded maximum weed control efficiency with respect to above weeds (75.27 – 86.60 %).
Effect on yield & yield attributes
The data on yield and yield attributes are presented in Tables 10 to 14. It revealed that the maximum number of tillers were observed in weed free check followed by the Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 21.0 g a.i/ha and 17.5 g a.i./ha. The test weight of rice was not significantly varied among the treatments. A significantly higher yield was observed under all the treatments as compared to untreated check. Maximum seed yield of 46.81 q/ha was observed in weed free check which was at par with Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 14.0, 17.5and 21.0 g a.i./ha, and market sample Chlorimuron Ethyl 10%+ Metsulfuron Methyl 10%WP @ 4.0 g a.i./ha.
Table 10: Bioefficacy of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC against weeds in Paddy crop after 15 days of application
Sr No. Treatments Dose (g a.i./ha) Grasses Sedges Broad leaved weeds
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 14.0 21.33 12.65 71.60 16.67 6.47 68.69 15.67 5.24 75.43
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 17.5 15.67 10.32 76.83 13.33 5.30 74.35 12.17 5.17 75.76
3 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 21.0 15.33 10.12 77.28 13.00 5.11 75.27 11.83 5.05 76.32
4 Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP (market sample) 4.0 16.00 10.72 75.93 13.67 8.37 59.50 11.94 8.12 61.93
5 Pyrazosulfuron ethyl10%WP (Market sample) 15.0 18.33 12.14 72.74 15 9.56 53.74 14.62 10.54 50.58
6 Chlorimuron Ethyl 25%WP (market sample) 6.0 17.67 11.42 74.36 14.67 9.74 52.87 11.33 9.29 56.44
7 Weed free check – Hand weeding 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
8 Untreated control 28.67 44.54 21.5 20.67 21.5 21.33
SE 0.10 0.54 0.16 0.41 0.17 0.51
C.D. at 5% 0.32 1.64 0.49 1.24 0.52 1.56

Table 11: Effect of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC on major weeds in Paddy crop after 15 days of application
Sr No. Treatments Dose (g a.i./ha) Echinochloa spp. Cyperus deformis Fimbristylis miliacea
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 14.0 5.67 1.86 73.95 6.13 2.56 69.60 4.33 2.16 71.73
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 17.5 4.67 1.42 80.11 4.67 2.28 72.92 2.67 1.74 77.23
3 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 21.0 4.43 1.18 83.47 4.50 2.07 75.42 2.33 1.62 78.80
4 Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP (market sample) 4.0 4.50 1.33 81.37 4.87 2.23 73.52 3.00 1.82 76.18
5 Pyrazosulfuron ethyl10%WP (Market sample) 15.0 5.00 1.74 75.63 5.00 2.35 72.09 3.67 1.96 74.35
6 Chlorimuron Ethyl 25%WP (market sample) 6.0 4.67 1.52 78.71 4.96 2.32 72.45 3.33 2.08 72.77
7 Weed free check – Hand weeding 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
8 Untreated control 12.00 7.14 9.67 8.42 7.67 7.64
SE 0.08 0.42 0.07 0.26 0.11 0.13
C.D. at 5% 0.28 1.28 0.21 0.80 0.34 0.39
* Mean of three replications
Table 12: Bioefficacy of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC against weeds in Paddy crop after 30 days of application
Sr No. Treatments Dose (g a.i./ha) Grasses Sedges Broad leaved weeds
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 14.0 23.33 14.11 75.54 17.42 7.69 73.78 18.00 6.24 81.46
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 17.5 17.00 11.84 79.47 14.74 7.64 73.95 15.67 5.21 84.52
3 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 21.0 16.67 11.38 80.27 14.33 6.62 77.42 14.33 4.51 86.60
4 Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP (market sample) 4.0 17.33 12.68 78.02 15.14 6.78 76.88 15.00 5.67 83.16
5 Pyrazosulfuron ethyl10%WP (Market sample) 15.0 18.15 13.00 77.46 15.26 10.52 64.13 17.33 14.67 56.43
6 Chlorimuron Ethyl 25%WP (market sample) 6.0 17.50 12.80 77.81 15.72 12.69 56.73 17.67 12.13 63.97
7 Weed free check – Hand weeding 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.00
8 Untreated control 34.28 57.68 27.00 29.33 24.67 33.67
SE 1.06 0.40 0.75 1.03 1.08 1.06
C.D. at 5% 3.18 1.20 2.27 3.12 3.26 3.20

Table 13: Effect of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC on major weeds in Paddy crop after 30 days of application
Sr No. Treatments Dose (g a.i./ha) Echinochloa spp. Cyperus deformis Fimbristylis miliacea
Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE Weed count/
m2 Dry wt. (g/ m2) % WCE
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 14.0 9.33 5.18 70.96 7.67 5.18 71.38 5.67 3.52 72.87
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 17.5 6.00 3.13 82.46 5.33 3.78 79.12 3.33 2.14 83.57
3 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 21.0 5.33 2.86 83.97 4.67 3.16 82.54 3.00 1.86 85.74
4 Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP (market sample) 4.0 6.67 3.26 81.73 5.67 3.40 81.22 3.67 2.20 83.10
5 Pyrazosulfuron ethyl10%WP (Market sample) 15.0 8.33 4.10 77.02 6.67 4.33 76.08 4.67 2.68 79.38
6 Chlorimuron Ethyl 25%WP (market sample) 6.0 8.00 3.89 78.20 6.00 4.18 76.91 4.00 2.42 81.40
7 Weed free check – Hand weeding 2 weeding 0.00 0.00 100.00 0.00 0.00 100.00 0.00 0.00 100.16
8 Untreated control 15.67 17.84 11.33 18.10 9.33 12.92
SE 0.80 0.49 0.70 0.54 1.10 0.26
C.D. at 5% 2.50 1.50 2.16 1.66 3.31 0.78
* Mean of three replications,

Table 14: Effect of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC application on yield and yield attributing characters of Paddy crop
S. No Treatments
Doses (g a. i./ha) Plant Height (cm) days after application No of tillers / hill Av. panicle length (cm) Test wt. (g) Grain yield (q/ha) Straw Yield
(q/ha)
15 30 45 60
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 14.0 24.67 61.67 96.25 109.67 13.73 15.80 11.38 43.84 37.62
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 17.5 25.17 62.44 102.50 112.17 14.80 16.52 12.23 44.54 39.40
3 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 21.0 25.00 60.33 103.00 113.42 15.07 16.87 12.36 45.89 40.79
4 Metsulfuron Methyl 10%+ Chlorimuron Ethyl 10%WP (market sample) 4.0 24.87 59.20 102.75 112.00 14.96 16.15 12.17 44.12 40.28
5 Pyrazosulfuron ethyl10%WP (Market sample) 15.0 24.07 60.80 101.73 110.47 13.14 15.67 11.64 40.13 35.86
6 Chlorimuron Ethyl 25%WP (market sample) 6.0 24.54 62.00 100.88 110.77 14.67 15.87 11.92 39.02 35.49
7 Weed free check – Hand weeding 2 weeding 24.67 63.67 103.00 114.33 15.18 17.06 12.59 46.81 39.60
8 Untreated control 23.33 57.89 92.50 104.33 11.13 14.28 11.30 32.41 26.37
SE 0.68 3.05 3.22 1.72 0.51 0.67 0.60 0.86 1.46
C.D. at 5% NS NS 9.92 5.29 1.54 2.06 NS 2.58 4.49
* Mean of three replications
Phytotoxicity:
After spraying, the paddy crop was continuously monitored for any phytotoxicity symptoms and crop health as described under methodology; as such there was no phytotoxicity effect (rating 0) in all dosages of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC in paddy crop during 2019 (Table 15).
Table 15: Studies on Phyto toxicity of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC on rice crop.
S.N. Treatment Doses
(ml or g/ kg seeds) Epinasty
R1 R2 R3 Mean
1 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 14.00 0 0 0 0
2 Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC 28.00 0 0 0 0
3 Untreated control ---
Mean of three replications
From the tables 10 to 15 above, chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 17.5 g a.i./ha resulted in significantly lower count of weeds as compared to untreated check. Also, Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 17.5 g a.i./ha was statistically on par with Chlorimuron Ethyl 10%+ Metsulfuron Methyl 10%WP(market sample) @ 4.0 g a.i./ha respectively in reducing the population of weeds at 15 and 30 days after application. The maximum grain yield of 46.81 q/ha was observed in weed free plot which was statistically at par with 45.89 and 44.54 q/ha registered by Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 21.0 and 17.5 g a.i./ha, respectively. Further it can be seen that as such there was no phytotoxicity effect (rating 0) in all the dosages of Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 28.0gm/ha on transplanted paddy crop. Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5%EC @ 14.0 g a.i./ha ( 40 ml per hectare) can be used for effective management of Echinocloa and Cyperus weeds in transplanted paddy crop.
The combination of Chlorimium ethyl 15% and Pyrazosulfuron-ethyl 5% EC is safe and reduces toxicity on the paddy crop and soil with the use of the active components in lower concentration as compared to original herbicides concentration which is being Chlorimium ethyl 25% WP and Pyrazosulfuron-ethyl 10% EC.
Both the synergistic combinations Pyrazosulfuron-ethyl 10%+ Sulfosulfuron 50%WP and Chlorimuron ethyl 15% + Pyrazosulfuron-ethyl 5% EC have showed efficacy in controlling grassy weeds, sedges and broad-leaf weeds in paddy. These combinations also resulted in increased growth and yield of the paddy crop without showing any phytotoxicity on the crop. Particularly, these combinations include the active ingredients in reduced dosage/concentration as compared to the market sample which is being sulfosulfuron 75% WP, chlorimuron ethyl 25% WP and pyrazosulfuron-ethyl 10% EC and therefore, can reduce the toxicity of the combination on the crop and soil.
Advantages of the Present Invention:
1. The synergistic combination of the present invention results in significantly lower count of grassy weeds, sedges and broad-leaf weeds (BLW’s) mainly Echinochloa spp., Dctyloctenium aegypticum and Eleusine Indica as compared to the untreated check.
2. The synergistic combination of the present invention is significantly superior from its individual herbicide available in market in reducing the population of Echinochloa spp., Dctyloctenium aegypticum and Eleusine Indica at 15, 30, 45 and 60 days after application.
3. The dosage of herbicides used in the combination is less than the dosage of alone herbicide available in the market and thus safeguard the environment.
4. The synergistic combination shows no phytotoxicity effect in paddy crop.
5. The synergistic combination of the present invention provides improved yield as compared to the untreated check; In case of weed free check, the yield is at par with the yield obtained from weed free check at its lower dosages of 45.0 and 60.0 a.i/hectare.

We claim:

1.A synergistic herbicidal combination comprising:
a first herbicide present in the ratio of 99-1% by weight and
a second herbicide present in the ratio of 1-99% by weight,
wherein both the first and second herbicides belong to a class of sulfonyl urea.

2. The synergistic herbicidal combination as claimed in claim 1, wherein the first herbicide is present in the ratio of 30-1% by weight and the second herbicide is present in the ratio of 1-50% by weight.

3. The synergistic herbicidal combination as claimed in claim 1, wherein the first herbicide is present in the ratio of 10-5% by weight and the second herbicide is present in the ratio of 15-50% by weight.

4. The synergistic herbicidal combination as claimed in claim 1, wherein the first and second herbicide is selected from selected from the group consisting of amidosulfuron, azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethametsulfuron-methyl, cinosulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron-methyl-sodium, imazosulfuron, metsulfuron-methyl, nicosulfuron, oxasulfuron, primisulfuron-methyl, prosulfuron, pyrazosulfuron-ethyl, rimsulfuron, sulfometuron-methyl, sulfosulfuron, thifensulfuron-methyl, triasulfuron, tribenuron-methyl, and triflusulfuron-methyl, preferably the first herbicide is selected from pyrazosulfuron-ethyl and the second herbicide is selected from sulfosulfuron or chlorimuron-ethyl.

5. The synergistic herbicidal combination as claimed in claim 1, wherein the combination is selected from pyrazosulfuron-ethyl 10% and Sulfosulfuron 50% WP or chlorimuron-ethyl 15% and pyrazosulfuron-ethyl 5% EC.

6. The synergistic herbicidal combination as claimed in claim 1, wherein the first and second herbicide is present in the ratio of 1:3 to 1:5.

7. A synergistic herbicidal composition comprising the herbicidal combination as claimed in any one of claims 1-6 along with one or more agriculturally acceptable excipients.

8. The composition as claimed in claim 7, wherein the agriculturally acceptable excipient is selected from the group consisting of a stabilizer, a disintegrating agent, an antifoaming agent, a wetting agent, a dispersing agent, binding agent, an emulsifying agent and water.

9. The composition as claimed in claim 7, wherein the composition is in the form of solid or liquid composition, preferably in the form of emulsifying concentrates, wet dispersible powder and wet dispersible granules.

10. The synergistic herbicidal combination as claimed in claim 1 or the composition comprising the synergistic combination as claimed in claim 7 for its use in controlling the grassy weeds, sedges and broad-leaf weeds (BLW’s) preferably Echinochloa spp., Dctyloctenium aegypticum and Eleusine Indica in a paddy crop.