Plant treatment compositions particularly effective in the control of Heteranthera limosa on rice crops, and methods for their use

Abstract

Provided are improved agricultural processes for the improved cultivation of rice wherein the crops are treated to control undesired vegetative growth using a plant treatment composition comprising both halosulfuron and thifensulfuron to provide improved herbicidal efficacy against Heteranthera limosa, commonly referred to as duck salad. Also provided are compositions useful in the improved agricultural processes, as well as herbicidal treatment regimens. Unexpectedly high rates of efficacy against Heteranthera limosa, amongst rice plant in rice crops are disclosed.

Claims

1. An agricultural process for the improved cultivation of rice wherein the crops are treated to control undesired vegetative growth using a plant treatment composition comprising both halosulfuron and thifensulfuron in synergistically effective amounts in order to provide improved herbicidal efficacy against Heteranthera limosa present in rice crops, the process comprising the step of: applying the said plant treatment composition to rice crops to control against Heteranthera limosa which may be present in the rice crops.

2. A process according to claim 1 wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio of about 4:3 of halosulfuron to thifensulfuron in a plant treatment composition as applied to the rice crop.

3. A process according to claim 1, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio of about 1:0.125 of halosulfuron to thifensulfuron in a plant treatment composition as applied to the rice crop.

4. A process according to claim 1, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio of about 0.66:0.08 of halosulfuron to thifensulfuron in a plant treatment composition as applied to the rice crop.

5. A process according to claim 1, wherein the plant treatment composition additionally comprises a biologically active material which exhibits or provides pesticidal, herbicidal, disease control, fungicidal, mildew control, or plant growth regulating effects.

6. Plant treatment compositions for providing herbicidal efficacy against Heteranthera limosa present in rice crops, wherein said plant treatment compositions comprise synergistically effective amounts of both halosulfuron and thifensulfuron.

7. A plant treatment composition according to claim 6, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a respective weight ratio of about 4:3 in the plant treatment composition as applied to the rice crop.

8. A plant treatment composition according to claim 6, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a respective weight ratio of about 1:0.125 in the plant treatment composition as applied to the rice crop.

9. A plant treatment composition according to claim 6, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a respective weight ratio of about 0.66:0.08 in the plant treatment composition as applied to the rice crop.

10. A plant treatment composition according to claim 6, wherein the plant treatment composition additionally comprises a biologically active material which exhibits or provides pesticidal, herbicidal, disease control, fungicidal, mildew control or plant growth regulating effects.

11. A plant treatment composition according to claim 6 wherein the halosulfuron is represented by the following structure: ##STR00006## wherein R.sub.7 is hydrogen or is a C.sub.1-C.sub.6 straight or branched alkyl group.

12. A plant treatment composition according to claim 11, wherein R.sub.7 is hydrogen, methyl or ethyl.

13. A plant treatment composition according to claim 12 wherein the halosulfuron is methyl, 3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylic acid.

14. A plant treatment composition according to claim 6 wherein the thifensulfuron is represented by the following structure: ##STR00007##

15. A process according to claim 1, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio of about 22.42-2.23:1 of halosulfuron to thifensulfuron in the plant treatment composition as applied to the rice crop.

16. A process according to claim 15, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio of about 8.37-2.23:1 of halosulfuron to thifensulfuron in the plant treatment composition as applied to the rice crop.

17. A process according to claim 1, wherein the plant treatment composition is applied to a rice crop at the following stages of growth: (a) preemergent, and (b) 10-14 days post emergence.

18. A process according to claim 15, wherein the plant treatment composition is applied to a rice crop at the following stages of growth: (a) preemergent, and (b) 10-14 days post emergence.

19. A process according to claim 1, wherein the plant treatment composition comprises halosulfuron, thifensulfuron and a liquid carrier, and which composition excludes further biologically active materials which exhibit or provide pesticidal, disease control, fungicidal, mildew control, herbicidal or plant growth regulating effects.

20. A process according to claim 1, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio range of about 1:0.12-1:1.2 of halosulfuron to thifensulfuron in a plant treatment composition as applied to the rice crop.

21. A process according to claim 1, wherein in the plant treatment composition comprising both halosulfuron and thifensulfuron the synergistically effective amounts of the halosulfuron and thifensulfuron is any combination of thifensulfuron methyl with halosulfuron methyl which, when compared to either an otherwise like composition having a like amount of thifensulfuron methyl but without halosulfuron methyl being present, or a like composition having a like amount of halosulfuron methyl but without thifensulfuron methyl being present.

.Iadd.22. A method for controlling undesired vegetative growth in a rice crop comprising applying a plant treatment composition comprising halosulfuron and thifensulfuron to rice crops to control against undesired vegetative growth that may be present in the rice crops, wherein the weight ratio of halosulfuron to thifensulfuron is 8.37:1..Iaddend.

.Iadd.23. The method of claim 22, wherein the undesired vegetative growth is spiny Amaranth (Amaranth spinosus), barnyard grass (Echinochloa crusgalli), bindweed (Calystegia sepium), Burcucumber (Sicyas angulatus), California Arrowhead (Sagittaria montevidensis), common Cocklebur (Xanthium strumarium), Corn Spurry (Spergula arvensis), wooly Cupgrass (Eriochloa villosa), Dayflower (Commelina erecta), Dogbane Hemp, (Apocynum cannabinum), Eclipta (Ecilpta prostrata), rice flatsedge (Cyperus iria), Philadelphia Fleabane (Erigeron philadelphicus), Foxtail, (Galinsoga), Golden Crownbeard (Verbesina encliodes), Goosefoot, Groundsel, common (Senecio vulgaris), Horsenettle, (Solanum carolinense), Horseweed/Marestail (Erigeron Canadensis), Horsetail (Equisetum), Jimsonweed (Datura stramonium), Itchgrass (Rottboellia cochinchinensis), Jointvetch (Aeschynomene), Johnsongrass rhizome, seedling (Sorghum halepense), Kochia (Kochia scoparia), Ladysthumb (Polygonum persicaria), Lambsquarter, common (Chenoposium album), Mallow, Venice (Hibiscus trionum), common Milkweed (Asclepias syriaca), honeyvine Milkweed (Ampelamus albidus), Millet, Wild Proso (Paniucum miliaceum), Morningglory, Ivyleaf (Ipomoea hederacea), Tall Morningglory (Ipomoea purppurea), wild Mustard (Sinapis arevensis), Black Nightshade (Solanum americanum), yellow Nutsedge (Cyperus exculentus), purple Nutsedge (Cyperus rotundus), oats, Fall Panicum (Paniucm dichotomiflorum), Texas Panicum (Panicum texanum), Maypop Passionflower (Passiflora incarnate), Redroot Pigweed (Amarunthus retroffiexus), smooth Pigweed (Amaranthus hybridus), common Pokeweed (Phytolacca Americana), Purslane (Portulaca oleracea), Quackgrass (Elytrigia repense), wild Radish (Rapharius raphanistrum), common Ragweed (Ambrosia artemisiifolia), giant Ragweed (Ambrosia trifida), Redstem (Ammania auriculata), Ricefield Bulrush (Scirpus mucronatus), Italian Ryegrass (Lollum multiflorum), Sandbur, Sesbania, Hemp (Sesbania exaltata), Shattercane (Sorghum bilcolor) Signalgrass, broadleaf, Shepherdspurse (capsella bursa-pastoris (L.) medicus), prickly Sida, Smallflower Umbrellaplant, Pennsylvania smartweed (Polyfonum pensylvanisum), Sorghum Almum, Canada Thistle (Cirsium arvense), Sunflower (Helianthus annuus) or Velvetleaf (Abutilan theophrasti)..Iaddend.

.Iadd.24. The method of claim 22, wherein the undesired vegetative growth is Amaranth (Amaranth spinosus), barnyard grass (Echinochloa crusgalli), bindweed (Calystegia sepium), Burcucumber (Sicyas angulatus), common Cocklebur (Xanthium strumarium), Corn Spurry (Spergula arvensis), Eclipta (Ecilpta prostrata), rice flatsedge (Cyperus iria), Philadelphia Fleabane (Erigeron philadelphicus), (Galinsoga), Golden Crownbeard (Verbesina encliodes), Goosefoot, Groundsel, Horsenettle, (Solanum carolinense), Horseweed/Marestail (Erigeron Canadensis), Horsetail (Equisetum), Jimsonweed (Datura stramonium), Jointvetch (Aeschynomene), Kochia (Kochia scoparia), Ladysthumb (Polygonum persicaria), Lambsquarter, common (Chenoposium album), Mallow, Venice (Hibiscus trionum), common Milkweed (Asclepias syriaca), honeyvine Milkweed (Ampelamus albidus), Morningglory, Ivyleaf (Ipomoea hederacea), Tall Morningglory (Ipomoea purppurea), wild Mustard (Sinapis arevensis), yellow Nutsedge (Cyperus exculentus), purple Nutsedge (Cyperus rotundus), Maypop Passionflower (Passiflora incarnate), Redroot Pigweed (Amarunthus retroffiexus), smooth Pigweed (Amaranthus hybridus), common Pokeweed (Phytolacca Americana), Purslane (Portulaca oleracea), wild Radish (Rapharius raphanistrum), common Ragweed (Ambrosia artemisiifolia), giant Ragweed (Ambrosia trifida), Redstem (Ammania auriculata), Ricefield Bulrush (Scirpus mucronatus), Sesbania, Hemp (Sesbania exaltata), Shepherdspurse (capsella bursa-pastoris (L.) medicus), prickly Sida, Smallflower Umbrellaplant, Sunflower (Helianthus annuus) or Velvetleaf (Abutilan theophrasti)..Iaddend.

.Iadd.25. The method of claim 22, wherein the composition excludes further biologically active materials which exhibit or provide pesticidal, disease control, fungicidal, mildew control, herbicidal or plant growth regulating effects..Iaddend.

.Iadd.26. The method of claim 23, wherein the composition excludes further biologically active materials which exhibit or provide pesticidal, disease control, fungicidal, mildew control, herbicidal or plant growth regulating effects..Iaddend.

.Iadd.27. The method of claim 24, wherein the composition excludes further biologically active materials which exhibit or provide pesticidal, disease control, fungicidal, mildew control, herbicidal or plant growth regulating effects..Iaddend.

.Iadd.28. The process of claim 1, wherein the synergistically effective amounts of halosulfuron to thifensulfuron is a weight ratio of 8.37:1 of halosulfuron to thifensulfuron in a plant treatment composition as applied to the rice crop..Iaddend.

.Iadd.29. A method for controlling undesired vegetative growth in a rice crop comprising applying a plant treatment composition comprising halosulfuron and thifensulfuron to rice crops to control against undesired vegetative growth that may be present in the rice crops, wherein the plant treatment compositions are applied post-emergence..Iaddend.

.Iadd.30. The method of claim 22, wherein the undesired vegetative growth is Amaranth (Amaranth spinosus), barnyard grass (Echinochloa crusgalli), Bindweed (Calystegia sepium), Burcucumber (Sicyas angulatus), Common Cocklebur (Xanthium strumarium), Corn Spurry (Spergula arvensis), Eclipta (Ecilpta prostrata), Rice Flatsedge (Cyperus iria), Philadelphia Fleabane (Erigeron philadelphicus), (Galinsoga), Golden Crownbeard (Verbesina encliodes), Goosefoot, Groundsel, Horsenettle, (Solanum carolinense), Horseweed/Marestail (Erigeron Canadensis), Horsetail (Equisetum), Jimsonweed (Datura stramonium), Jointvetch (Aeschynomene), Kochia (Kochia scoparia), Ladysthumb (Polygonum persicaria), Common Lambsquarter (Chenoposium album), Venice Mallow (Hibiscus trionum), Common Milkweed (Asclepias syriaca), Honeyvine Milkweed (Ampelamus albidus), Ivyleaf Morningglory (Ipomoea hederacea), Tall Morningglory (Ipomoea purppurea), Wild Mustard (Sinapis arevensis), Yellow Nutsedge (Cyperus exculentus), Purple Nutsedge (Cyperus rotundus), Maypop Passionflower (Passiflora incarnate), Redroot Pigweed (Amarunthus retroffiexus), Smooth Pigweed (Amaranthus hybridus), Common Pokeweed (Phytolacca Americana), Purslane (Portulaca oleracea), Wild Radish (Rapharius raphanistrum), Common Ragweed (Ambrosia artemisiifolia), Giant Ragweed (Ambrosia trifida), Redstem (Ammania auriculata), Ricefield Bulrush (Scirpus mucronatus), Hemp Sesbania (Sesbania exaltata), Shepherdspurse (capsella bursa-pastoris (L.) medicus), Prickly Sida, Smallflower Umbrellaplant, Sunflower (Helianthus annuus) or Velvetleaf (Abutilan theophrasti)..Iaddend.

.Iadd.31. The method of claim 29, wherein the weight ratio of halosulfuron to thifensulfuron is 8.37-8:1..Iaddend.

.Iadd.32. The method of claim 29, wherein the composition is applied at a rate of 0.06-0.30 oz thifensulfuron/acre..Iaddend.

.Iadd.33. The method of claim 29, wherein the composition excludes further biologically active materials which exhibit or provide pesticidal, disease control, fungicidal, mildew control, herbicidal or plant growth regulating effects..Iaddend.

.Iadd.34. A method for controlling undesired vegetative growth in a rice crop comprising applying a plant treatment composition comprising halosulfuron and thifensulfuron to rice crops to control against undesired vegetative growth that may be present in the rice crops, wherein the weight ratio of halosulfuron to thifensulfuron is 8.37-8:1..Iaddend.

.Iadd.35. The method of claim 34, wherein the undesired vegetative growth is Amaranth (Amaranth spinosus), Barnyardgrass (Echinochloa crusgalli), Bindweed (Calystegia sepium), Burcucumber (Sicyas angulatus), Common Cocklebur (Xanthium strumarium), Corn Spurry (Spergula arvensis), Eclipta (Ecilpta prostrata), Rice Flatsedge (Cyperus iria), Philadelphia Fleabane (Erigeron philadelphicus), (Galinsoga), Golden Crownbeard (Verbesina encliodes), Goosefoot, Groundsel, Horsenettle, (Solanum carolinense), Horseweed/Marestail (Erigeron Canadensis), Horsetail (Equisetum), Jimsonweed (Datura stramonium), Jointvetch (Aeschynomene), Kochia (Kochia scoparia), Ladysthumb (Polygonum persicaria), Common Lambsquarter (Chenoposium album), Venice Mallow (Hibiscus trionum), Common Milkweed (Asclepias syriaca), Honeyvine Milkweed (Ampelamus albidus), Ivyleaf Morningglory (Ipomoea hederacea), Tall Morningglory (Ipomoea purppurea), Wild Mustard (Sinapis arevensis), Yellow Nutsedge (Cyperus exculentus), Purple Nutsedge (Cyperus rotundus), Maypop Passionflower (Passiflora incarnate), Redroot Pigweed (Amarunthus retroffiexus), Smooth Pigweed (Amaranthus hybridus), Common Pokeweed (Phytolacca Americana), Purslane (Portulaca oleracea), Wild Radish (Rapharius raphanistrum), Common Ragweed (Ambrosia artemisiifolia), Giant Ragweed (Ambrosia trifida), Redstem (Ammania auriculata), Ricefield Bulrush (Scirpus mucronatus), Hemp Sesbania (Sesbania exaltata), Shepherdspurse (capsella bursa-pastoris (L.) medicus), Prickly Sida, Smallflower Umbrellaplant, Sunflower (Helianthus annuus) or Velvetleaf (Abutilan theophrasti)..Iaddend.

.Iadd.36. The method of claim 34, wherein the composition excludes further biologically active materials which exhibit or provide pesticidal, disease control, fungicidal, mildew control, herbicidal or plant growth regulating effects..Iaddend.

.Iadd.37. The method of claim 29, further comprising applying a composition comprising halosulfuron and thifensulfuron before said rice crop emerges..Iaddend.

.Iadd.38. A method for controlling undesired vegetative growth in a rice crop comprising applying a composition comprising halosulfuron and thifensulfuron to rice crops to control against undesired vegetative growth that may be present in the rice crops, wherein halosulfuron and thifensulfuron are the only herbicides in said composition..Iaddend.

.Iadd.39. The method of claim 38, wherein the undesired vegetative growth is Amaranth (Amaranth spinosus), Barnyardgrass (Echinochloa crusgalli), Bindweed (Calystegia sepium), Burcucumber (Sicyas angulatus), Common Cocklebur (Xanthium strumarium), Corn Spurry (Spergula arvensis), Eclipta (Ecilpta prostrata), Rice Flatsedge (Cyperus iria), Philadelphia Fleabane (Erigeron philadelphicus), (Galinsoga), Golden Crownbeard (Verbesina encliodes), Goosefoot, Groundsel, Horsenettle, (Solanum carolinense), Horseweed/Marestail (Erigeron Canadensis), Horsetail (Equisetum), Jimsonweed (Datura stramonium), Jointvetch (Aeschynomene), Kochia (Kochia scoparia), Ladysthumb (Polygonum persicaria), Common Lambsquarter (Chenoposium album), Venice Mallow (Hibiscus trionum), Common Milkweed (Asclepias syriaca), Honeyvine Milkweed (Ampelamus albidus), Ivyleaf Morningglory (Ipomoea hederacea), Tall Morningglory (Ipomoea purppurea), Wild Mustard (Sinapis arevensis), Yellow Nutsedge (Cyperus exculentus), Purple Nutsedge (Cyperus rotundus), Maypop Passionflower (Passiflora incarnate), Redroot Pigweed (Amarunthus retroffiexus), Smooth Pigweed (Amaranthus hybridus), Common Pokeweed (Phytolacca Americana), Purslane (Portulaca oleracea), Wild Radish (Rapharius raphanistrum), Common Ragweed (Ambrosia artemisiifolia), Giant Ragweed (Ambrosia trifida), Redstem (Ammania auriculata), Ricefield Bulrush (Scirpus mucronatus), Hemp Sesbania (Sesbania exaltata), Shepherdspurse (capsella bursa-pastoris (L.) medicus), Prickly Sida, Smallflower Umbrellaplant, Sunflower (Helianthus annuus) or Velvetleaf (Abutilan theophrasti)..Iaddend.

.Iadd.40. The method of claim 38, wherein the weight ratio of halosulfuron to thifensulfuron is 8.37-8:1..Iaddend.

.Iadd.41. The method of claim 38, wherein the composition is applied at a rate of 0.06-0.30 oz thifensulfuron/acre..Iaddend.

.Iadd.42. A plant treatment composition comprising halosulfuron and thifensulfuron, wherein halosulfuron and thifensulfuron are the only herbicides in said composition..Iaddend.

.Iadd.43. The plant treatment composition of claim 42, wherein the weight ratio of halosulfuron to thifensulfuron is 8.37-8:1..Iaddend.

Description

EXAMPLES

(1) A number of separate test areas were used to evaluate the efficacy of certain treatment regimens for the control of undesired vegetative growth, more specifically, the control of Heteranthera limosa, commonly referred to as duck salad in a rice crop planted with rice. The following Table illustrates the efficacy of plant treatment compositions according to the invention which included combination of halosulfuron and thifensulfuron, as well as comparative examples which did not include the combination of halosulfuron and thifensulfuron. The former are identified by a digit prefixed by the letter E, the latter comparative examples by a digit prefixed by the letter C in the Table. The identity of the constituents and timings of application of are as indicated following. The tests were performed in Louisiana, USA at a controlled facility, during the growth of the crop Heteranthera limosa, commonly referred to as duck salad was observed to be prevalent amongst the rice plants of the rice crop. The compositions in each of the examples were formed as tank mixes in water, and applied to the rice crop utilizing a backpack mounted hand held sprayer, pressurized with CO.sub.2.

(2) In the following table, the NIS indicates a non-ionic surfactant, and COC indicates a crop oil concentrate.

(3) TABLE-US-00001 TABLE % control of Heteranthera % damage to treated limosa rice crops Growth stage of Evaluation at Evaluation at Evaluation at Evaluation at Treatment Application rate crop at 8 days post 20 days post 8 days post 20 days post Example: regimen (actives) application(s) emergence emergence emergence emergence C1 (control) --none-- 0% 0% 0% 0% C2 (a) PERMIT; (a) PERMIT at (a) 81% 74% 0% 0% and, 0.0314 lb preemergence; (b) PERMIT + active/acre; and; NIS and, (b) 10-14 days (b) PERMIT at post emergence 0.0314 lb active/acre + NIS at 0.25% v/v per acre C3 (a) PERMIT + (a) PERMIT at (a) 94% 71% 10% 8% tribenuron; 0.0314 lb preemergence; and, active/acre + and; (b) PERMIT + tribenuron at (b) 10-14 days tribenuron + NIS 0.008 post emergence active/acre; and, (b) PERMIT at 0.0314 lb active/acre + tribenuron at 0.008 active/acre NIS at 0.25% v/v per acre % control of Heteranthera limosa Growth stage of Evaluation at 7 Evaluation at Evaluation at Treatment Application rate crop at days post 14 days post 26 days post Example: regimen (actives) application(s) emergence emergence emergence C4 (a) PERMIT + each (a) and (b) (a) preemergence; 69% 78% 43% COC; and, both: and; (b) PERMIT + PERMIT at 0.67 oz (b) 10-14 days post COC active/acre + 19.2 emergence fluid oz. COC per acre C5 (a) each (a) and (b) (a) preemergence; 71% 66% 23% thifensulfuron + both: and; COC; and, thifensulfuron at (b) 10-14 days post (b) 0.08 oz active/acre + emergence thifensulfuron + 19.2 fluid oz. COC COC per acre C6 (a) each (a) and (b) (a) preemergence; 91% 95% 55% thifensulfuron + both: and; COC; and, thifensulfuron at 0.3 oz (b) 10-14 days post (b) active/acre + emergence thifensulfuron + 19.2 fluid oz. COC COC per acre C7 thifensulfuron + thifensulfuron at preemergence 55% 61% 20% COC 0.08 oz active/acre + 19.2 fluid oz. COC per acre C8 thifensulfuron + thifensulfuron at 10-14 days post 44% 41% 30% COC 0.08 oz active/acre + emergence 19.2 fluid oz. COC per acre % control of Heteranthera % damage to treated rice limosa crops Growth stage of Evaluation at Evaluation at Evaluation at Evaluation at Treatment Application rate crop at 8 days post 20 days post 8 days post 20 days post Example: regimen (actives) application(s) emergence emergence emergence emergence E1 (a) PERMIT + (a) PERMIT at (a) 92% 93% 10% 0% thifensulfuron; 0.0314 lb preemergence; and, active/acre + and; (b) PERMIT + thifensulfuron at (b) 10-14 days thifensulfuron + 0.0038 lb post NIS active/acre; emergence and, (b) PERMIT at 0.0314 lb active/acre + thifeunsulfuron at 0.0038 lb active/acre + NIS at 0.25% v/v per acre E2 (a) PERMIT + (a) PERMIT at (a) 90% 94% 0% 0% thifensulfuron; 0.0314 lb preemergence; and, active/acre + and; (b) PERMIT + thifensulfuron at (b) 10-14 days thifensulfuron + 0.014 lb post NIS active/acre; emergence and, (b) PERMIT at 0.0314 lb active/acre + thifeunsulfuron at 0.014 lb active/acre + NIS at 0.25% v/v per acre % control of Heteranthera limosa Growth stage of Evaluation at 7 Evaluation at Evaluation at Treatment Application rate crop at days post 14 days post 26 days post Example: regimen (actives) application(s) emergence emergence emergence E3 (a) PERMIT + each (a) and (b) were: (a) preemergence; 94% 96% 63% thifensulfuron + PERMIT at 0.67 oz and; COC; and, active/acre + (b) 10-14 days post (b) PERMIT + thifensulfuron at 0.08 oz. emergence thifensulfuron + active/acre + 19.2 COC fluid oz. COC per acre E4 (a) PERMIT + each (a) and (b) were: (a) preemergence; 93% 98% 73% thifensulfuron + PERMIT at 0.67 oz and; COC; and, active/acre + (b) 10-14 days post (b) PERMIT + thifensulfuron at 0.3 oz. emergence thifensulfuron + active/acre + 19.2 COC fluid oz. COC per acre E5 (a) PERMIT + each (a) and (b) were: (a) preemergence; 95% 96% 60% thifensulfuron + PERMIT at 0.67 oz and; COC; and, active/acre + (b) 10-14 days post (b) PERMIT + thifensulfuron at 0.08 oz. emergence thifensulfuron + active/acre + 19.2 COC fluid oz. COC per acre E6 (a) PERMIT + each (a) and (b) were: (a) preemergence; 91% 98% 70% thifensulfuron + PERMIT at 0.67 oz and; COC; and, active/acre + (b) 10-14 days post (b) PERMIT + thifensulfuron at 0.08 oz. emergence thifensulfuron + active/acre + 19.2 oz. COC COC per acre E7 PERMIT + PERMIT at 0.67 oz preemergence 60% 69% 28% thifensulfuron + active/acre + COC thifensulfuron at 0.08 oz. active/acre + 19.2 fluid oz. COC per acre E8 PERMIT + PERMIT at 0.67 oz 10-14 days post 46% 40% 25% thifensulfuron + active/acre + emergence COC thifensulfuron at 0.08 oz. active/acre + 19.2 fluid oz. COC per acre
With reference to the constituents identified in the foregoing Table,
PERMIT=

(4) ##STR00003##
wherein R.sub.7 is methyl.
NIS=a nonionic surfactant.
COC=supplied as Agridex (ex. Helena Chem. Co.)
thifensulfuron=

(5) ##STR00004##
tribenuron=

(6) ##STR00005##

(7) The results reported on the table are evaluations which were performed based on visual evaluation of like-sized areas of each of the treated rice plots which like-sized areas were randomly selected. The Table reports both the % control or the degree of control of undesired vegetative growth of Heteranthera limosa in the evaluated areas of each of the rice crops, demonstrating the efficacy of the E1 and E2 plant compositions, compared to the plant treatment composition of the comparative examples, namely the untreated control C1, as well as further comparative treatment regimens C2 and C3. The observed and results reported results are surprising and would be unexpected by a skilled artisan, suggesting a synergistic benefit of the combination of halosulfuron and thifensulfuron in the plant treatment composition. It was also observed that sulfonylurea based herbicide treatment preparations did not deleteriously affect the crop of the rice varieties tested.

(8) Surprisingly the substitution of a further triazinylsulfonulurea herbicide, viz., tribenuron-methyl for the thifensulfuron as per C3 provided significantly poorer control of Heteranthera limosa especially 20 days post application than plant treatment compositions and regimens according to the invention, namely E1 and E2. Such illustrates the unexpected nature of the specific combination of the claimed inventive plant treatment compositions.

(9) The benefits of this discovery are real and are several. As is readily seen from the foregoing, it is contemplated that the use of combination of halosulfuron and thifensulfuron may provide similarly effective and surprisingly good control of Heteranthera limosa which could not be previously attained with prior art compositions. Further, the foregoing suggests that the use of combination of halosulfuron and thifensulfuron provides highly effective control or eradiction of Heteranthera limosa at lower net application rates using the use of combination of halosulfuron and thifensulfuron than might be otherwise required using other herbicidal compounds other than the disclosed specific use of combination of halosulfuron and thifensulfuron taught herein. Both of the above provide for simultaneous control, with decreased loadings of herbicidal compounds applied to unit areas of crops (e.g., acre, hectare), thus permitting improved crop harvest yields per unit area, with reduced loadings of herbicides per said unit area, therefore also providing an important environmental benefit.