Plant protecting and regulating compositions – Plant growth regulating compositions – Plural active ingredients
Reexamination Certificate
2000-08-31
2002-09-17
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Plural active ingredients
C504S127000, C504S148000, C504S363000, C504S364000, C514S628000, C514S937000
Reexamination Certificate
active
06451731
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to pesticidal compositions useful in agriculture and related industries. More specifically, the present invention relates to concentrated pesticidal compositions containing a solid pesticide and a liquid pesticide, and to a method of killing or controlling unwanted life forms using such compositions.
BACKGROUND OF THE INVENTION
Solid pesticides are commonly formulated as emulsifiable suspension concentrates, wherein typically a pesticidally active ingredient in a solid particulate state is suspended in a non-active liquid carrier. The liquid carrier in such concentrates can be aqueous or non-aqueous, for example a hydrocarbon oil or other organic liquid, and is selected such that the solid pesticide has low solubility in the liquid carrier. Most solid pesticides are of low solubility in water and can be formulated as aqueous suspension concentrates, or as non-aqueous suspension concentrates wherein the liquid carrier is not an effective solvent for the pesticide.
Suspension concentrate formulations preferably have a high concentration of active ingredient, have good storage stability, and are easy to use. In particular, because these concentrates are typically diluted with water at the time of use, they must be readily emulsified in water, and have good emulsion stability in the diluted state.
Physical stability of suspension concentrates, both during storage and during use, is of particular concern with these formulations having a solid particulate phase and a continuous liquid phase. Suspension concentrates are inherently unstable in a gravitational field because of difference in density between the solid pesticide and the liquid carrier, which can result in separation of the formulation over time into a pesticide-rich layer and a carrier-rich layer. In extreme cases, phase separation occurs, wherein the solid particulate pesticide, typically the denser phase, settles at the bottom of the liquid phase. It is therefore generally necessary to include one or more suspension aid(s) in the formulation to assist in maintaining suspension of the solid and thereby improve the physical stability. If separation occurs, it is preferred that the solid can be readily resuspended with minimum agitation of the formulation.
Further, a pesticidal suspension concentrate to be used in the agricultural industry is typically diluted with water to prepare a dilute sprayable composition which is then applied by spraying to soil and/or plants in a field, for example by means of conventional spraying equipment. At the time of use, therefore, it is desirable that the suspension concentrate is readily emulsified in water, with no more than a minimal and acceptable amount of segregation of components into distinct layers referred to in the industry as “creaming”, and/or no more than a minimal and acceptable amount of sedimentation. In order to accomplish this, one or more surfactants or emulsifiers are therefore also typically included in suspension concentrates to improve dispersibility in water.
Suspension concentrates having an oil as the liquid carrier are particularly troublesome and require an emulsifier that is capable, by a process of emulsification, of dispersing the oil without forming gels or lumps, and distributing the pesticide in the aqueous phase of a dilute sprayable composition. This emulsification must take place quickly, without complications.
A number of pesticides, including for example some highly popular and effective herbicidal agents that are especially useful for controlling undesirable plant species by post-emergence application, are routinely supplied as water-soluble salts in aqueous solution. Unless converted to a more lipophilic form, for example alkyl esters, such pesticides are generally very poorly soluble in non-aqueous carriers such as organic solvents and oils. Examples of such salt-forming pesticides include the herbicide N-phosphonomethylglycine, also known as glyphosate, DL-homoalanin-4-yl(methyl)phosphinic acid, also known as glufosinate, and several herbicides of the imidazolinone class, such as 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid, also known as imazapyr.
U.S. Pat. No. 5,078,782 to Nielsen & M{dot over (a)}nsson describes a suspension concentrate composition comprising a solid particulate pesticide, for example a herbicide such as phenmedipham or glyphosate, suspended in an oily carrier, for example a refined paraffinic oil having 0-17% aromatic content, with one or more surfactants. Also described is a suspension concentrate having phenmedipham in suspension and the herbicide triallate in solution in the oily carrier. The content of the oily component in the composition as a whole is said to be 20-90% by weight.
U.S. Pat. No. 5,397,766 to Dexter describes an emulsifiable suspension concentrate composition comprising solid particulate glyphosate and/or an imidazolinylnicotinic acid, e.g., imazapyr, in the acid form thereof, dispersed in a water-immiscible inert liquid carrier such as a non-paraffinic aromatic solvent. The composition is said to further comprise an anionic surfactant and a nonionic surfactant, and optionally an antifoam agent and a suspending or thickening agent.
The great majority of pesticides, for example herbicides, are of very low solubility in water and are not convertible to water-soluble salts. Many of these pesticides are readily soluble in organic solvents and are typically formulated as emulsifiable concentrates comprising a solution of pesticide in an organic solvent carrier, together with one or more surfactants as emulsifiers to facilitate emulsification on preparation by the end-user of a dilute aqueous sprayable composition.
A relatively small number of pesticides are liquid at ambient temperatures, having a melting point lower than about 15° C. Such pesticides illustratively include the pre-emergence chloroacetamide herbicides 2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide, also known as acetochlor, and 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, also known as metolachlor, and can optionally be formulated as emulsifiable concentrates with only a minimal amount of an organic solvent, or none at all.
It is frequently desired in the art to coformulate as a liquid concentrate a salt-forming pesticide with a pesticide having low solubility in water, herein referred to for convenience as a “water-insoluble” pesticide. For example, a combination of a salt-forming post-emergence herbicide such as glyphosate or glufosinate with a water-insoluble pre-emergence herbicide, for example a chloroacetamide herbicide such as acetochlor or metolachlor, is useful for killing or controlling already emerged weeds and for providing residual control of weeds that would otherwise later emerge.
Roundup® Ultra herbicide of Monsanto, which contains as active ingredient glyphosate in the form of its isopropylammonium salt, is labeled by the manufacturer for use in tank-mixture with Dual® and Dual® II herbicides of Novartis, which contain as active ingredient metolachlor, Frontier® herbicide of BASF, which contains as active ingredient the chloroacetamide herbicide dimethenamid, and Harness® herbicide of Monsanto and Surpass® and TopNotch® herbicides of Zeneca, which contain as active ingredient acetochlor.
It is often of benefit to provide a single concentrate composition containing both a salt-forming pesticide and a water-insoluble liquid pesticide, for example glyphosate and acetochlor respectively. Typically this has been accomplished by providing a concentrated emulsion, for example an oil-in-water emulsion, wherein the salt-forming pesticide is present, usually in the form of a water-soluble salt, in an aqueous phase and the water-insoluble pesticide is present in an oil phase. The herbicidal product FieldMaster® of Monsanto contains glyphosate in the form of its isopropylammonium salt in the aqueous phase and acetochlor in the oil phase; also present in this product is a third herbicide, atrazine, dispersed in the aqueous pha
Agbaje Henry E.
Carter Deborah H.
Hawkins Shannon K.
Powers Tracy A.
Stern Alan J.
Clardy S. Mark
Monsanto Company
Schaper Joseph A.
Senniger Powers Leavitt & Roedel
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