WO2000053018A1

WO2000053018A1 - Herbicidal composition

Info

Publication number: WO2000053018A1
Application number: PCT/CA2000/000238
Authority: WO
Inventors: John S. Lojek
Original assignee: Ecoval Corporation
Priority date: 1999-03-11
Filing date: 2000-03-07
Publication date: 2000-09-14
Also published as: EP1179982A1; EP1179982B1; AU3138100A; CA2371887A1; DE60005662D1; ATE250857T1; MXPA01009152A

Abstract

The compositions in aqueous solutions of (a) glyphosate, acetic acid, citric acid and surfactant, (b) glyphosate, acetic acid, citric acid and alkyl polyoxyethylene glycol ether, (c) alkyl polyoxyethylene glycol ether, (d) alkyl polyoxyethylene glycol ether and glyphosate, and (e) acetic acid, citric acid and alkyl polyoxyethylene glycol ether. Compositions of mixtures of ingredients exhibit synergistic activity.

Description

TITLE HERB1CIDAL COMPOSITION

Field of the Invention The present invention relates to aqueous herbicidal compositions and, in particular embodiments to aqueous herbicidal compositions in which the combination of ingredients in the herbicidal composition exhibits synergistic herbicidal properties. In particular, the present invention relates to the use of alkyl polyoxyethylene glycol ether as a herbicide, combinations of alkyl polyoxyethylene glycol ether with other herbicides, and synergistic combinations of acetic acid, citric acid, glyphosate and surfactant and/or alkyl polyoxyethylene glycol ether.

Background of the Invention Many herbicidal compositions exist which are effective in killing all vegetation or selected vegetation. Many such herbicidal compositions are based on chemicals with complex structures, some of which are toxic to other life forms.

Combinations of active herbicidal ingredients with surfactants to achieve a better weed control are known. Such combinations can provide specific benefits e.g. better spreading on or wetting of foliage. Surfactants in combination with appropriate toxins are registered for use as herbicides.

Even though certain herbicides may be mixed to provide better overall weed control, this in not possible with other herbicides. One of the latter is glyphosate, which is effective on many weeds but less so on dandelions, which tend to be damaged but not killed. The surviving plants tend to re-grow. To overcome this problem, attempts have been made to combine glyphosate with other post-emergence herbicides e.g. 2,4-D. Synergistic combinations were not obtained, and antagonistic responses were observed. Other attempts have been made to improve the rate of visible damage by glyphosate alone by addition of surfactant. However, even literature on a known formula that is referred to as a "fast acting formula" states that visible symptoms such as browning or yellowing of leaves will occur within one or two days. With dandelions, it usually takes 3-4 days for these visible symptoms to occur.

The combination of acetic and citric acid is known as a non-selective herbicide. For example, combinations of acetic acid and citric acid exhibit synergistic herbicidal properties compared to acetic acid and citric acid alone, as disclosed in U.S. 5705455. However, even though the combination produces rapid top kill, most perennial weeds rapidly re-grow, thereby requiring multiple applications. Improvement in re-grow control would have significant benefits. The present registered rate of application for the combination of acetic acid and citric acid requires a substantial amount of active ingredients, making it too expensive for other than spot applications of the herbicidal composition. Large scale use would require a much more active combination of ingredients to be economical. It is known that certain herbicidal soaps can be used for post emergence herbicidal applications. However, these products do not prevent re-growth, unless the roots of such weeds as dandelions are split prior to application and the herbicide is poured on the damaged root. This makes it impractical to use these products as perennial weed control agents.

Summary of the Invention

Herbicidal compositions have now been found that are effective against a variety of types of weeds, aspects of which are effective in preventing re- growth of certain perennial weeds. Accordingly, an aspect of the present invention provides a herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and surfactant in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of any of (i) glyphosate, (ii) acetic acid in combination with citric acid and (iii) surfactant at the same concentration.

Another aspect of the present invention provides a herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of any of (i) glyphosate, (ii) acetic acid in combination with citric acid and (iii) alkyl polyethylene glycol ether at the same concentration. A further aspect of the present invention provides a herbicidal composition comprising alkyl polyoxyethylene glycol ether in aqueous solution. Yet another aspect of the present invention provides a herbicidal composition comprising alkyl polyoxyethylene glycol ether in combination with glyphosate in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of either of (i) glyphosate and (ii) alkyl polyoxyethylene glycol ether at the same concentration.

A further aspect of the invention provides a herbicidal composition comprising a combination of acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of either of (i) acetic acid in combination with citric acid and (ii) alkyl polyoxyethylene glycol ether at the same concentration.

The present invention also provides use of such herbicidal compositions, especially in post-emergence applications.

Detailed Description of the Invention

The present invention relates to aqueous herbicidal compositions, and particularly to herbicidal compositions in which the combination of ingredients exhibits synergistic effects as a herbicide. Such synergistic compositions exhibit more effective herbicidal activity than a corresponding composition of any of the ingredients alone in aqueous solution. In addition it has been found that some herbicidal compounds e.g. glyphosate, may be used in combination with other ingredients at concentrations that are less than the concentrations generally understood to be effective and for which such herbicide is registered. An embodiment of the present invention provides a herbicidal composition which comprises alkyl polyoxyethylene glycol ether in aqueous solution. An example of an alkyl polyoxyethylene glycol ether is Witconol™ SN-90, which is available from Witco.

In another embodiment of the invention, the herbicidal composition comprises a combination of glyphosate, acetic acid, citric acid and surfactant in a clear solution. The composition exhibits synergistic herbicidal activity in comparison with any of the ingredients in aqueous solution at the same concentration. For instance the composition exhibits synergistic activity compared with glyphosate, with acetic acid in combination with citric acid and with surfactant at the same concentrations in aqueous solution. A further embodiment provides a herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution. The composition exhibits synergistic herbicidal activity compared with glyphosate, with acetic acid in combination with citric acid and with alkyl polyoxyethylene glycol ether at the same concentrations in aqueous solution.

In another embodiment, the herbicidal composition comprises alkyl polyoxyethylene glycol ether in combination with glyphosate in aqueous solution. The composition exhibits synergistic herbicidal activity in comparison with aqueous solutions of glyphosate or alkyl polyoxyethylene glycol ether at the same concentration.

In yet another embodiment, the herbicidal composition comprises a combination of acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution. The composition exhibits synergistic herbicidal activity compared with acetic acid in combination with citric acid and with alkyl polyoxyethylene glycol ether at the same concentration in aqueous solution. The weight ratio of acetic acid to citric acid, when present, in the herbicidal composition may vary over a wide range, for instance, in the range of from about 10:1 to about 1 :1 , preferably in the range, of 4:1 to 1 :1 , on a weight basis. In embodiments, the weight ratio of acetic acid to citric acid is in the range of 4:1 to 2:1.

The herbicidal composition in use may contain up to 100 g/l of acetic acid and 50 g/l of citric acid when present, with the preferred amount of acetic acid being up to 10 g/l and especially up to 4 g/l. The composition should contain at least 1 g/l of acetic acid and 0.5 g/l of citric acid, if present, in the herbicidal composition. Preferred compositions contain about 4 g/l acetic acid and 2 g/l of citric acid. When surfactants are present in the herbicidal composition, it is believed that a wide variety of surfactants may be used. However, a particularly preferred surfactant is available as Sponto™ 300T. The amount of surfactant should be in the range of 0.1-40 g/l, preferably 1-5 g/l.

The registered dosage rate for the glyphosate available as Roundup™ is 7 g/l in aqueous solution. In the present invention, the amount of glyphosate should be less than 5 g/l, and especially less than 4 g/l.

The herbicidal compositions containing alkyl polyoxyethylene glycol ether should utilize concentrations of at least 10 g/l. Lower amounts may be used in combinations with acetic acid and citric acid and/or glyphosate. The herbicidal compositions of the present invention may be formulated for use with a variety of vegetation. In particular, the herbicidal compositions may be formulated for use against perennial weeds, especially dandelions. The compositions may be formulated to prevent re-growth of such weeds. However, as exemplified herein, the compositions may be formulated with a variety of other types of vegetation.

It is to be understood that the effectiveness of herbicidal compositions disclosed herein may vary with the type of plant that is being treated. While compositions illustrated herein are generally effective against weeds, perennials and grass, it is also illustrated herein that compositions containing alkyl polyoxyethylene glycol ether are particularly effective against herbaceous (woody) plants, as exemplified by poinsettias. As illustrated, a composition disclosed herein as being effective against dandelions was not effective against herbaceous plants.

The present invention provides synergistic combinations of ingredients that act as herbicidal compositions. In some instances, the ingredients are known to act as herbicides, but at concentrations substantially above those found to be effective in combination according to the present invention. Thus, in one aspect of the present invention, reduced amounts of known herbicides may be used with consequently reduced effects of toxicity, if present, with respect to other life forms. In other aspects of the invention, the combinations provide for increased herbicidal activity at similar concentrations, thereby rendering the herbicide more effective in application.

The present invention is illustrated by the following examples:

Example I

Individual well established dandelion plants growing in a field were marked and then sprayed with different herbicidal compositions until the liquid of the composition ran off the leaves of the dandelion plants. Each experiment was replicated four times i.e. four different dandelion plants were sprayed with each composition.

The glyphosate of Run 2 was used at the registered rate of application for this herbicide.

The plants were observed for initial top kill and subsequent re-growth, after 1 , 7 and 28 days.

The results obtained are shown in Table I.

Note: aa = acetic acid ca = citric acid glyphosate = Roundup® Reg. No. 24,299 (P.C.P. Act), used as isopropylamine salt SN-90 = Witconol SN-90 from Witco, an alkyl polyoxyethylene glycol ether Sponto = Sponto™300T from Witco

Results clearly show that neither glyphosate at registered rate of 7g/litre nor the combination of acetic acid plus citric acid prevented re-growth of dandelions, even though both herbicides caused leaf damage. The acetic acid plus citric acid combination (Run 1) showed initial damage in less than 24 hours, whereas glyphosate damage (Run 2) first became visible (leaf yellowing) after three days. Both compositions showed substantial re-growth after 28 days.

The combination of (a) acetic acid and citric acid at the registered rate with (b) the regular rate of glyphosate (Run 3) resulted in very rapid top kill (24 hours) plus 100% control of re-growth i.e. there was no re-growth after 28 days. Very similar results were obtained using even lower rates of acetic acid and citric acid with half the recommended rate of glyphosate (Run 4).

The treatments of this Example clearly show synergistic response of the combinations, which essentially eliminated top growth and re-growth at substantially below presently used application rates.

Example II

Well established dandelions were transplanted from the field to individual 5 inch plastic pots, using the original field soil. The dandelions were allowed to re-establish themselves for a period of at least 8 weeks in a greenhouse.

After the top growth of the dandelion had completely covered the soil surface, the plants were subjected to treatment with herbicidal compositions in the greenhouse. Each plant was sprayed with a herbicidal composition using the procedure of Example I, and observations were recorded. The results are shown in Table II.

The results in the greenhouse showed that the combination of acetic and citric acids with SN-90 resulted in better re-growth control, especially when Run 5 is compared to Run 7. Run 5 provides 90% re-growth control as compared only to 25% control in Run 7.

Runs 8 and 9 indicate that the surfactant SN-90 alone is herbicidal. Run 11 indicates synergistic activity of combinations resulting in 24 hour top kill and complete re-growth control of dandelions.

Example III

Individuals cucumber seeds, variety Straight 8, were seeded in 4 inch pots using a standard peat moss vermiculite mixture. After germination in a greenhouse, seedlings 2 cm tall were selected for experiments, and sprayed with a combination of water and various amounts of SN-90 surfactant using the procedure of Example I. Each experiment was replicated four times.

The results obtained are shown in Table III.

The treatments of this example show that SN-90 is a post-emergence herbicide resulting in rapid kill of cucumber seedlings. Sponto 300T shows no such activity.

Example IV

A similar procedure to that of Example III was used with grass seed, using a mixture of various seeds commonly used for establishing a shady lawn. The seedlings were allowed to grow for about three weeks in a greenhouse until individual seedlings were 5-7 cm tall.

The seedlings were sprayed with a combination of water and various amounts SN-90 surfactant, with each experiment being replicated four times. Observations were recorded for several days. The results obtained are given in Table IV.

Results with grass seedlings confirm that SN-90 alone is a herbicide, causing a rapid kill of grass seedlings. Example V

The procedure of Example II was repeated using the composition of Run 9 with glyphosate added at half the recommended rate. Observations on the dandelions were recorded at 1 , 2, 3, 6 and 14 days.

The results obtained are given in Table V.

Table V: Greenhouse Dandelion Results with Glyphosate

% Kill (per # of days)

Run Solution 14

18 3.5 g glyphosate + 10 g SN-90/1000 ml water 22 58 68 91 100

^"he results shown that glyphosate activity can be enhanced by adding SN-90, resulting in greater top kill even at half the present registered rate. This indicates superior re-growth control over field results.

Example VI

Poinsettias were selected as a representative of herbaceous plants. The poinsettias were sprayed with either a formula containing (i) 50g acetic acid + 25 g citric acid + 10 g Sponto 300T per litre or (ii) 50g acetic acid + 25g acid + 10g SN-90 per litre. After seven days, the plants that had been sprayed with formula (ii) i.e. the formula containing SN-90, showed severe damage on all leaves and stems. However, the plants that had been sprayed with formula (i) i.e. the formula containing Sponto 300 T, showed some leaf damage but remained green and alive. After four weeks, the plants sprayed with formula (ii) i.e. the formula containing SN-90, were dead, with both the leaves and the stems showing no signs of re-growth. In contrast, the plants sprayed with formula (i) i.e. the formula containing Sponto 300T formulation, remained alive and growing. This example demonstrates that a formula of the present invention shows superior activity in both damaging as well as killing well-established herbaceous plants that were previously believed to be impossible or difficult to kill.

Claims

CLAIMS:

1. A herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and surfactant in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of any of (i) glyphosate, (ii) acetic acid in combination with citric acid and (iii) surfactant at the same concentration.

2. A herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of any of (i) glyphosate, (ii) acetic acid in combination with citric acid and (iii) alkyl polyethylene glycol ether at the same concentration.

3. A herbicidal composition comprising alkyl polyoxyethylene glycol ether in combination with glyphosate in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of each of (i) glyphosate and (ii) alkyl polyoxyethylene glycol ether at the same concentration.

4. The herbicidal composition of any one of Claims 1-3 in which the amount of glyphosate is less than 5 g/l.

5. The herbicidal composition of Claim 4 in which the amount of glyphosate is less than 4 g/l.

6. A herbicidal composition comprising a combination of acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of either of (i) acetic acid in combination with citric acid and (ii) alkyl polyoxyethylene glycol ether at the same concentration.

7. The herbicidal composition of any one of Claims 1-6 in which, if acetic acid and citric acid are present, the weight ratio of acetic acid to citric acid is in the range of 10: 1 to 1 : 1.

8. The herbicidal composition of Claim 7 in which the weight ratio of acetic acid to citric acid is in the range of 4:1 to 1 :1.

9. The herbicidal composition of any one of Claims 1-8 in which, if acetic acid and citric acid are present, the concentration of acetic acid is 1-100 g/l and the concentration of citric acid is 0.5-50 g/l.

10. The herbicidal composition of any one of Claims 1-9 in which, if acetic acid is present, the concentration is 1-10 g/l.

11. The herbicidal composition of any one of Claims 1 -10 in which, if surfactant is present, the concentration is 0.1-40 g/l.

12. The herbicidal composition of Claim 11 in which the concentration of surfactant is 1-5 g/l.

13. The herbicidal composition of any one of Claims 1-12 in which, if alkyl polyoxyethylene glycol ether is present, the concentration is at least 10 g/l.

14. A herbicidal composition comprising alkyl polyoxyethylene glycol ether in aqueous solution.

15. The herbicidal composition of Claim 14 in which the concentration of alkyl polyoxyethylene glycol ether is at least 10 g/l.

16. Use of a herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and surfactant in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of any of (i) glyphosate, (ii) acetic acid in combination with citric acid and (iii) surfactant at the same concentration.

17. Use of a herbicidal composition comprising a combination of glyphosate, acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of any of (i) glyphosate, (ii) acetic acid in combination with citric acid and (iii) alkyl polyethylene glycol ether at the same concentration.

18. Use of herbicidal composition comprising alkyl polyoxyethylene glycol ether in combination with glyphosate in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of each of (i) glyphosate and (ii) alkyl polyoxyethylene glycol ether at the same concentration.

19. The use of any one of Claims 16-18 in which the amount of glyphosate is less than 5 g/l.

20. The use of Claim 19 in which the amount of glyphosate is less than 4 g/l.

21. Use of a herbicidal composition comprising a combination of acetic acid, citric acid and alkyl polyoxyethylene glycol ether in aqueous solution, said composition exhibiting synergistic herbicidal activity in comparison with aqueous solutions of either of (i) acetic acid in combination with citric acid and (ii) alkyl polyoxyethylene glycol ether at the same concentration.

22. The use of any one of Claims 16-21 in which, if acetic acid and citric acid are present, the weight ratio of acetic acid to citric acid is in the range of 10:1 to 1 :1.

23. The use of Claim 22 in which the weight ratio of acetic acid to citric acid is in the range of 4:1 to 1 :1.

24. The use of any one of Claims 16-23 in which, if acetic acid and citric acid are present, the concentration of acetic acid is 1-100 g/l and the concentration of citric acid is 0.5-50 g/l.

25. The use of any one of Claims 16-24 in which, if acetic acid is present, the concentration is 1-10 g/l.

26. The use of any one of Claims 16-25 in which, if surfactant is present, the concentration is 0.1-40 g/l.

27. The use of Claim 26 in which the concentration of surfactant is 1- 5 g/l.

28. The use of any one of Claims 16-27 in which, if alkyl polyoxyethylene glycol ether is present, the concentration is at least 10 g/l.

29. Use of a herbicidal composition comprising alkyl polyoxyethylene glycol ether in aqueous solution.

30. The use of Claim 29 in which the concentration of alkyl polyoxyethylene glycol ether is at least 10 g/l.

31. Use of alkyl polyoxyethylene glycol ether in aqueous solution as a post-emergence herbicide.

32. The use of Claim 21 in treatment of a herbaceous plant.

33. The use of any one of Claims 16-31 for treatment of weeds.

34. The use of any one of Claims 16-31 for treatment of perennials.

35. The use of any one of Claims 16-31 for treatment of grass.

36. The use of any one of Claims 16-31 as a post-emergence herbicide.