Plant protecting and regulating compositions – Plant growth regulating compositions – Organic active compound containing
Reexamination Certificate
1999-04-23
2001-03-27
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Organic active compound containing
C504S362000
Reexamination Certificate
active
06207617
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to formulations of plant treatment compounds. In particular, this invention relates to concentrate formulations which, following dilution, dissolution or dispersion in water, are applied to foliage of a plant.
A plant treatment compound, as defined herein, is a chemical substance, whether naturally or synthetically derived, which is applied to a plant to result in expressing a desired biological activity. By “biological activity” is meant the elicitation of a stimulatory, inhibitory, regulatory, therapeutic, toxic or lethal response in the plant or in a pathogen, parasite or feeding organism present in or on the plant.
A concentrate composition, as defined herein, contains at least about 20% by weight, and up to about 90% by weight, in total of one or more plant treatment compounds.
The present invention applies particularly to a class of foliar-applied plant treatment compounds that are acidic. As conventionally defined, an acid is a proton donor. A compound described herein as an “acid” or in an “acid form” is to be understood as having a molecular structure with one or more proton-donating groups, in none of which is the proton substituted by a salt-forming cation. A salt-forming cation herein means any cationic entity other than a proton. It will be recognized, however, that a formulation containing a plant treatment compound in acid form can also contain a salt of the plant treatment compound.
Plant treatment compounds to which the invention can usefully be applied include, but are not limited to, chemical pesticides (such as herbicides, algicides, fungicides, bactericides, viricides, insecticides, aphicides, miticides, nematicides and molluscicides), plant growth regulators, fertilizers and nutrients, gametocides, defoliants, desiccants, mixtures thereof, and the like. The invention has particular application for such compounds if they are capable of existing in an acid form and eliciting a biological response as described above in such acid form.
BACKGROUND OF THE INVENTION
Plant treatment compounds, including foliar-applied herbicides, have often been formulated as concentrates with a surfactant. When water is added to such a concentrate, the resulting sprayable composition is, by virtue of the surfactant provided therein, more easily and effectively retained on foliage (ie., leaves and other photosynthesizing organs) of plants. Surfactants can also provide other benefits, including improved contact of spray droplets with a waxy leaf surface and, in some cases, improved penetration of the accompanying plant treatment compound into the interior of leaves. Through these and perhaps other effects, particular surfactants have long been known to increase the biological effectiveness of herbicide compositions, or other compositions of plant treatment compounds, when present in such compositions.
Thus, for example, the herbicide glyphosate (N-phosphonomethylglycine), usually in the form of a water-soluble salt thereof, has been formulated with surfactants such as those having polyoxyalkylene (polyoxyethylene and/or polyoxypropylene) moieties, including, among other surfactants, polyoxyalkylene alkylamines.
The term “alkyl” as an element in the description of a surfactant herein is used in the sense in which it is conventionally used in surfactant-related art to embrace unsaturated as well as saturated hydrocarbyl chains, and includes linear and branched chains. In general, alkyl groups useful as hydrophobic moieties in surfactants contain about 8 to about 22, most commonly about 12 to about 18, carbon atoms.
Surfactants have been combined with glyphosate or other plant treatment compounds in (a) liquid or solid concentrate compositions provided by the supplier and diluted, dissolved or dispersed in water by the user before application, (b) ready-to-use dilute aqueous compositions provided by the supplier and applied without further dilution by the user, and (c) user-prepared dilute aqueous compositions made by adding separate compositions of plant treatment compound (e.g., glyphosate) and surfactant to water prior to application. Such user-prepared dilute aqueous compositions are known as “tank-mix” compositions.
Some surfactants, although chemically stable, are physically incompatible with certain plant treatment compounds, particularly in aqueous liquid concentrate compositions. For example, an aqueous micellar solution of most classes of nonionic surfactant, including polyoxyethylene alkylether surfactants, does not tolerate the presence of high concentrations of salts imparting high ionic strength to the solution. This is true, for example, of a polyoxyethylene alkylether surfactant in a concentrated aqueous solution of a salt of glyphosate. Such physical incompatibility can be manifested immediately on preparation of the composition, or over time or when exposed to certain temperature conditions or regimes, leading to inadequate shelf-life of the composition. A common effect of physical incompatibility is separation of the composition into distinct phases. Other problems that can arise from such incompatibility include formation of aggregates large enough to interfere with commercial handling and application, for example by blocking spray nozzles.
Many plant treatment compounds are commercially packaged as a liquid concentrate formulation that, while being a concentrate, nevertheless contains a significant amount of water. The packaged concentrate, containing a plant treatment compound as active ingredient, is shipped to distributors or retailers. Ultimately, the packaged concentrate is purchased by an end user, who dilutes the concentrate by adding water in accordance with label instructions on the package. The fully diluted material is then sprayed on plant foliage.
A significant portion of the cost of such a packaged concentrate is the cost of transporting the concentrate from the manufacturing site to the location where the end user purchases it. Any liquid concentrate formulation that contains relatively less water and thus more active ingredient would reduce the cost per unit amount of active ingredient. However, one important limit on the ability of the manufacturer to increase concentration (ie., “loading”) of the active ingredient in a concentrate formulation is the physical stability of that formulation. With some combinations of formulation ingredients, an upper limit to loading of the active ingredient is reached beyond which any further reduction of water content in the concentrate causes physical instability (e.g., separation into discrete layers), which generally makes the concentrate commercially unacceptable.
Until now, the problems presented by such physical instability have been avoided by such expedients as (a) formulating the concentrate in solid rather than liquid form, (b) restricting surfactant choice to the relatively narrow range of surfactants showing good physical compatibility with high ionic strength solutions, or (c) limiting the concentration of a surfactant such as a polyoxyethylene alkylether to a low level, often in combination with a second surfactant or other coformulant that acts as a compatibility agent. Illustrations of such expedients are provided by literature on glyphosate formulations.
It is known to include a relatively high concentration of a polyoxyethylene alkylether surfactant together with a glyphosate salt in a solid formulation. For example, U.S. Pat. No. 4,931,080 discloses a solid powder composition containing the polyoxyethylene alkylether surfactant Plurafac™ A-39 of BASF and glyphosate trimethylsulfonium salt, in a weight ratio of 1:1.64. The weight ratio of surfactant to glyphosate acid equivalent (a.e.) in this composition can be calculated to be about 1:1.13. Two other compositions are disclosed having the same ingredients in an even higher weight ratio of surfactant to glyphosate a.e. (1:0.86 and 1:0.69).
Solid formulations such as those disclosed in above-cited U.S. Pat. No. 4,931,080 have numerous benefits but most end users prefer the convenience of liquid formu
Clardy S. Mark
Finkelstein Ira D.
Forbes James C.
Howrey Simon Arnold & White , LLP
Monsanto Compant
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