Plant protecting and regulating compositions – Plant growth regulating compositions – Plural active ingredients
Reexamination Certificate
2000-09-27
2003-05-27
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Plural active ingredients
C504S128000, C504S362000, C504S363000, C514S938000, C514S963000
Reexamination Certificate
active
06569809
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to pesticidal and/or plant growth regulating compositions useful in agriculture and related industries. More specifically, the present invention relates to liquid concentrate compositions containing at least two active ingredients. One of the active ingredients is water-soluble and the other is substantially water-insoluble. The liquid concentrate composition is suitable, following dilution in water, for application to plants or to soil. Active ingredients that can be formulated in compositions of the invention include pesticides, for example herbicides, algicides, fungicides, bactericides, viricides, insecticides, acaricides, nematicides and molluscicides, and plant growth regulators.
BACKGROUND OF THE INVENTION
For many purposes in agriculture and related endeavors it is desired to apply simultaneously two or more biologically active compounds, each of which is a pesticide or plant growth regulator, to the same locus. This is best accomplished by including the two or more compounds in a single composition which is applied, for example by spraying, to target plants or soil. Frequently such a composition is prepared by the user in the field by adding measured amounts of two or more concentrate compositions of the individual active ingredients to water in a spray tank, sometimes together with other ingredients. A composition prepared in this way is often known as a “tank-mix”.
More conveniently, however, a single concentrate composition containing the two or more biologically active compounds, together with other ingredients if necessary or desirable, is provided to the user, who simply dilutes this composition in water prior to application. Such a composition is often known as a “package-mix”. Package-mix compositions have many advantages, including reduced handling, reduced risk of dosage error, reduced packaging, etc. Package-mix compositions can take the form of solid materials such as powders or granules, but for many purposes liquid compositions are preferred.
A liquid concentrate package-mix composition of two active ingredients can be useful in a wide variety of applications, depending on the utility of the individual active ingredients. For example, it may be desired to simultaneously apply two insecticidal, fungicidal or herbicidal active ingredients in order to kill or control a wider spectrum of insect, fungal or weed species than can be killed or controlled with either one of the active ingredients alone. Alternatively, it may be desired to simultaneously apply two active ingredients having different modes of action or target sites, for example a contact herbicide and a systemic herbicide, to obtain improved effectiveness on a single species. Many other situations can readily be envisaged where a package-mix of two active ingredients is useful.
While effectiveness for the intended purpose is an important property determining the usefulness of a liquid concentrate package-mix composition, another very important property is storage stability of the composition. Chemical instability can sometimes be an issue but more commonly the primary issue is physical instability, manifested for example as phase separation, crystallization of an active or inert ingredient, settling or sedimentation of a particulate component, gelling, agglomeration, etc. Stability problems often do not become apparent immediately upon preparation of a composition, but instead are time-related. What constitutes an acceptable shelf-life for a particular product depends upon the product in question and the use to which it is put. In some cases a shelf-life of a few weeks or months is adequate, but more commonly an agricultural product is expected to remain stable under typical storage conditions for a minimum of one to two years. A product that is stable when stored for up to two years at temperatures of, say, 15° C. to 25° C. may relatively quickly exhibit instability problems if exposed to much higher temperatures, for example 50° C. to 60° C., or in a temperature cycling regime in which low temperatures (for example −10° C. to 0° C.) and higher temperatures (for example 25° C. to 35° C.) alternate.
Where both active ingredients are readily water-soluble or where both are water-insoluble, formulation of a storage-stable concentrate package-mix composition is generally fairly straightforward. However, where it is desired to provide a liquid package-mix composition of a water-soluble active ingredient with a water-insoluble active ingredient, in particular a solid (i.e., high melting point) water-insoluble active ingredient, formulation is much more difficult. This is because such a composition must be a two-phase or multiphase system, wherein the water-soluble compound is typically dissolved in an aqueous phase and the solid water-insoluble compound is typically either dispersed in the composition as a particulate phase, forming a suspension, or dissolved in an oil phase, the oil phase and aqueous phase together forming an emulsion. Although much teaching is available in the literature on stabilization of colloidal systems such as suspensions and emulsions, there remains a need for improved formulation technology where a physically and chemically stable liquid concentrate composition is desired containing a water-soluble pesticide or plant growth regulator and a solid water-insoluble pesticide or plant growth regulator.
In considering options for such a composition, an appropriate starting point is the formulation type known as a suspension concentrate (SC), wherein a finely particulate solid water-insoluble active ingredient is dispersed in a continuous aqueous phase having dissolved therein a water-soluble active ingredient. Tadros, Th. F. (1990) in a review article ‘Disperse systems in pesticidal formulations’,
Advances in Colloid and Interface Science
, 32, 205-234, summarized the main requirements for formulating an SC, namely the choice of dispersing agents and the choice of an anti-settling system.
According to Tadros, nonionic polymers and polyelectrolytes are the most preferred dispersing agents for SC formulations. Nonionic surfactants of the ethoxylate type are said to be adequate, provided they have enough ethylene oxide units to promote steric stabilization. Ionic surfactants are said to be the least attractive dispersing agents.
The anti-settling system most favored by Tadros for SC formulations is a “thickener” in the form of a viscosity modifying agent. Typical examples given are high molecular weight polymers such as hydroxyethyl cellulose or xanthan gum, or finely divided particulate materials such as bentonite or colloidal silica.
Suspoemulsions are a relatively recent development in pesticide formulation technology. These generally consist of a continuous aqueous phase in which two discontinuous phases are dispersed. One of the discontinuous phases is an oil phase and the other is a solid particulate phase. A suspoemulsion is therefore a mixture of a suspension and an oil-in-water emulsion. Tadros, in the above-cited review article, indicates that where both the oil phase and the solid particles can be dispersed using one surfactant and where the solid particles are insoluble in the oil phase, the general principles of stabilization of suspensions and emulsions can be applied also to suspoemulsions. Suspoemulsions are commonly considered in the art where it is desired to formulate a water-based concentrate package-mix composition of two water-insoluble active ingredients, one of which is liquid or readily soluble in oil and one of which is solid and relatively oil-insoluble.
Illustrative of the problems faced by the formulator desiring to prepare a liquid concentrate package-mix composition of a water-soluble active ingredient and a solid water-insoluble active ingredient are the particular problems faced where the water-soluble active ingredient is a salt of the herbicide N-phosphonomethylglycine (glyphosate) and the solid water-insoluble active ingredient is the herbicide 2-[7-fluoro-3,4-dihydro-3-oxo-4-(2-propyn
Kuchikata Masus
Sato Tatsuo
Clardy S. Mark
Monsanto Company
Schaper Joseph A.
Senniger Powers Leavitt & Roedel
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