Plant protecting and regulating compositions – Plant growth regulating compositions – Organic active compound containing
Reexamination Certificate
1999-07-08
2001-11-27
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Organic active compound containing
C504S320000
Reexamination Certificate
active
06323153
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the use of a selective herbicidal composition containing a carboxylic or phosphonic acid salt.
BACKGROUND OF THE INVENTION
Chemicals used to kill plants can be classified as either non-selective herbicides or selective herbicides. Non-selective herbicides kill all plants to which they are applied. An example of a non-selective herbicide is N-(phosphonomethyl) glycine, known commonly as glyphosphate or “Roundup®.” A selective herbicide kills only certain plants, that is, it is more toxic to some plants than to others. To be of practical use, a selective herbicide must have the ability to kill undesirable plants without affecting the remaining desirable plants. An example of such a chemical is the well known herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) which will selectively kill broad-leaved weeds in, for example, turf grass. However, there are many weeds which are not destroyed by 2,4-D. Furthermore, 2,4-D is toxic and can cause eye irritation and gastrointestinal disturbances if ingested. Some undesirable grasses, like crabgrass or bermudagrass, can be selectively removed from turf by the use of arsenic compounds, but these herbicides can be toxic to both humans and animals. Other turf weeds, such as nimblewill, are not affected by 2,4-D or arsenic compounds and can only be controlled chemically by using glyphosphate which kills not only the nimblewill but all of the desirable plants surrounding the nimblewill.
U.S. Pat. No. 5,668,086, herein incorporated by reference, discloses the use of a herbicidal composition containing diquat (1,1′-ethylene-2,2′-bipyridinium dibromide) or paraquat (1,1′-dimethyl-4,4′-bipyridinium dichloride) as contact herbicides. Diquat and paraquat have no selectivity but exhibit strong week-killing power by foliage treatment. In use, they are diluted with water. An ionic surfactant is further added so that the liquid can be applied evenly and ensure contact with the stems and leaves of the vegetation long enough to penetrate into the plant body. Unfortunately, the addition of the surfactant lowers the herbicidal effects of the composition. The reduction observed in the herbicidal effects observed in the composition is dependent upon the kind and amount of anionic surfactant used.
It is the primary object of this invention to provide a method for the selective control of certain undesirable vegetation using herbicides which are non-toxic to humans, animals and insects. It is a further object to provide such herbicides that also are odorless, water soluble and biodegradable.
SUMMARY OF THE INVENTION
Undesired vegetation may be killed by wetting the leaves of the vegetation with a herbicidally effective amount of a composition comprising water and a carboxylic or phosphonic acid salt known to form coordination compounds with calcium or magnesium ions. Coordination compounds are substances with chemical structures in which a central metal atom such as calcium is surrounded by groups of non-metallic atoms joined to it by chemical bonds.
Examples of the salts of acids which form complexes with calcium or magnesium ions and are useful in the invention are salts of at least one carboxylic or phosphonic acid selected from aminopolycarboxylic acids, aliphatic carboxylic acids, hydroxycarboxylic acids, amino acids, ether polycarboxylic acids, phosphonic acids and polyphosphonic acids.
The compositions of the invention act as selective herbicides. The composition may further contain a surfactant as well as other conventional adjuvants. Since the mode of action appears to be through the leaves of the vegetation, there is little, if any, residual herbicidal effect in the ground. Thus, it is possible to grow desirable plants adjacent to and around the treated area.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Unwanted vegetation may be killed by wetting the locus of the vegetation with an aqueous composition containing a carboxylic or phosphonic acid salt known to form coordination compounds with calcium or magnesium ions. In a preferred embodiment, the invention relates to a herbicidal composition containing, as the carboxylic acid salt, the salt of carboxylic or phosphonic acids selected from aminopolycarboxylic acids, aliphatic carboxylic acids, hydroxycarboxylic acids, amino acids, ether polycarboxylic acids, phosphonic acids and polyphosphonic acids.
The carboxylic and phosphonic acids for use in the composition include aminopolycarboxylic acids having from 1 to about 10 carbon groups, a C
1
-C
8
aliphatic carboxylic acid, a C
1
-C
8
hydroxycarboxylic acid, an amino acid and ether polycarboxylic acids having from two to about 10 carbon atoms. The phosphonic acids for use in the invention include phosphonic and polyphosphonic acids having between from two to about 12 carbon atoms.
Suitable for use as the salt are alkali metals, especially sodium, potassium, and lithium, as well as ammonium and amine. In addition, mixtures of these cations can be employed. The amines used to form the salts can be represented by the formula N(R)
3
or N(R)
4
+
wherein R is independently selected from hydrogen or a C
1
-C
8
alkyl group, a C
6
-C
14
aryl group or a C
7
-C
16
alkaryl or alkaryl group.
It is not necessary that the carboxylic or phosphonic acid salt be completely neutralized to be effective for use in the invention since only one of the acid groups of a polycarboxylic acid need be in the salt form.
Representative examples of the aminopolycarboxylic acid salts include salts of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), N-(2-hydroxyethyl)iminodiacetic acid (HIMDA), diethylenetriaminepentaacetic acid ((DTPA), N-(2-hydroxyethyl) ethylenediaminetriacetic acid (EDTA-OH) and glycol ether diaminetetraacetic acid (GEDTA).
Examples of the aliphatic acid salts include salts of oxalic acid, succinic acid, glutaric acid, and pyruvic acid. Exemplary of the amino acid salts include salts of glycine, alanine and lysine. Examples of the hydroxycarboxylic acid salts are salts of malic acid, citric acid, glycolic acid, lactic acid and tartaric acid.
Examples of the phosphonic acid salts include salts of iminodimethylphosphonic acid (IDP), alkyldiphosphonic acids (ADPAs) and polyphosphonic acid.
The herbicidal composition for use in the invention may further contain a mixture of two or more of the carboxylic or phosphonic acid salts referenced herein.
The active herbicidal composition is prepared by dissolving the carboxylic or phosphonic acid salt in water. The herbicide salt solution can also be prepared by mixing the free acid in water and adding the required basic compound (for example, lithium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, ammonium hydroxide, amine or quaternary ammonium hydroxide) in a sufficient amount to neutralize one or more of the acid groups. The addition could also be reversed, that is, the acid may be added to a water mixture of the required amount of basic compound.
The undesirable vegetation is then treated by wetting the leaves with the resulting herbicidal composition. Death of the wetted undesirable plants occur within one day to one week depending upon ambient temperature and the growing season of the undesirable plants. The younger the plant, the more susceptible it is to be killed. Under certain conditions, more than one treatment may be required to obtain complete control.
Weeds and grasses which may be controlled by the method of this invention include oxalis, quakegrass, crabgrass, bermudagrass, nimblewill, and speedwell.
The amount of carboxylic or phosphonic acid salt in the herbicidal composition varies with the weed to be destroyed and generally ranges from about 0.5 to about 20 wt. percent. The most effective concentration of carboxylic or phosphonic acid salt in the herbicidal composition is between from 1 and about 10 wt. percent. The effectiveness of weed control with the herbicides of the invention also depends on the ambient temperature at the time o
Clardy S. Mark
Falcon Lab LLC
Locke Lidell & Sapp LLP
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