Plant protecting and regulating compositions – Plant growth regulating compositions – Organic active compound containing
Reexamination Certificate
1999-04-23
2001-06-12
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Organic active compound containing
C504S362000
Reexamination Certificate
active
06245713
ABSTRACT:
FIELD OF THE INVENTION
The field of the present invention is that of exogenous chemical substances applied to foliage of plants, and more particularly that of compositions of such exogenous chemical substances having a high degree of biological effectiveness. The invention relates even more particularly to compositions having a low content of surfactants relative to the content of exogenous chemical substance, such compositions generally offering relatively low cost and the potential for high “loading”, or concentration, of the exogenous chemical substance.
The term “exogenous chemical substance” as used herein means a chemical substance, whether naturally or synthetically obtained, which is applied to a plant to result in expressing a desired biological activity. The term “biological activity” as used herein means 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. Examples of exogenous chemical substances include, but are not limited to, chemical pesticides (such as herbicides, algicides, fungicides, bactericides, viricides, insecticides, miticides, nematicides and molluscicides), plant growth regulators, fertilizers and nutrients, gametocides, defoliants, desiccants, mixtures thereof and the like.
The term “biological effectiveness” is used herein to denote the degree to which a desired biological activity is expressed upon application of an exogenous chemical substance to foliage of a plant, or alternatively to denote the dosage or rate of application of the exogenous chemical substance that results in the desired biological activity being expressed to a given degree. For example, where the exogenous chemical substance is a herbicide, biological effectiveness can be measured by the degree of inhibition of plant growth resulting from application of a particular rate of the herbicide, or by the application rate of the herbicide required to cause a particular degree of inhibition, e.g., 50% or 85% inhibition. Thus increased or enhanced biological effectiveness of a herbicide can be exhibited for example as an increased level of plant growth inhibition at a given rate of the herbicide, or as a reduction in the minimum rate of the herbicide giving a certain threshold level of plant growth inhibition.
BACKGROUND OF THE INVENTION
For many purposes in agriculture and related endeavors it is desired to treat plants with exogenous chemical substances of various kinds. Many exogenous chemical substances are applied to foliage (i.e., leaves and other non-woody above-ground parts) of a plant, and have a site of action in the plant either close to or remote from the locus of application. Such substances are referred to herein as foliar-applied exogenous chemical substances.
Typically, when an exogenous chemical substance is applied to foliage by plant treatment processes known in the art, only a small portion of the amount applied reaches sites of action in the plant where a desired biological activity of the exogenous chemical substance can be usefully expressed. It is therefore a major desideratum in agriculture and related endeavors to enhance the efficiency of delivery of foliar-applied exogenous chemical substances to their sites of action in plants, and thereby to enhance the biological effectiveness of the exogenous chemical substance for the purpose for which the exogenous chemical substance is used.
Application to foliage of an exogenous chemical substance by processes known in the art does not universally result in inefficient delivery to sites of action. In some situations such processes provide excellent biological effectiveness, even at a low use rate of the exogenous chemical substance. In other situations the same processes, using the same rate of the same exogenous chemical substance, provide inadequate biological effectiveness. Thus, these processes are inconsistent in the result they provide, or they cannot be relied upon to provide the desired result.
A problem is that it is seldom possible to identify in advance those situations where good biological effectiveness will be obtained, partly because so many factors influence efficiency of delivery. These factors include weather (temperature, relative humidity, daylength, cloudiness, precipitation, wind, etc.) preceding, during and following application, soil conditions (fertility, aeration, etc.), plant growth stage, health and physiological status, equipment-related inaccuracies in application, and other factors. Therefore, to help ensure reliable or consistent biological effectiveness of a foliar-applied exogenous chemical substance, the user typically applies the substance at a higher rate than is truly necessary in the majority of situations.
Variability in biological effectiveness in field conditions is an especially troublesome problem in the case of exogenous chemical substances that are acids, and are typically formulated as water-soluble salts in which the exogenous chemical substance is present in an anionic form. Sometimes by converting such acid substances to esters, this variability can be moderated; however, in many cases esters show reduced biological effectiveness, for example due to inadequate conversion back to the parent acid once inside the treated plant. There remains a strong need for enhanced biological effectiveness, and enhanced reliability of biological effectiveness, of foliar-applied exogenous chemical substances, particularly anionic exogenous chemical substances.
The term “anionic exogenous chemical substance” as used herein means an exogenous chemical substance whose molecular structure includes one or more acid, or proton-donating, sites, and is therefore capable of forming an anion in the presence of a proton acceptor. The term therefore embraces substances that are zwitterionic. In describing an exogenous chemical substance as “anionic” herein, it is not implied that the exogenous chemical substance is necessarily in anionic form or that it is dissociated.
Benefits of a process providing greater reliability of biological effectiveness include an ability to reduce rates of application of exogenous chemical substances without sacrificing consistency of biological effectiveness. Pressures felt by the agricultural industry to reduce pesticide, particularly herbicide, usage are well evidenced by symposia on the subject, such as that held in 1993 by the Weed Science Society of America and documented in
Weed Technology
8, 331-386 (1994). Reduced use rates bring rewards not only environmentally but also economically, as the cost per unit area treated decreases.
Foliar-applied exogenous chemical substances have frequently been applied together with amphiphilic materials, particularly amphiphilic surface-active agents, otherwise known as surfactants. Surfactants can influence biological effectiveness of a foliar-applied exogenous chemical substance in numerous ways.
When a dilute aqueous composition of an exogenous chemical substance is applied to foliage by conventional hydraulic spraying, the presence of surfactant in the dilute aqueous composition can alter the size distribution of the spray droplets, typically increasing the percentage of spray volume in the form of small droplets and reducing the percentage of spray volume in the form of large droplets. As smaller droplets have lower momentum than larger droplets, these smaller droplets are less likely to rebound from a foliar surface and consequently are more likely to be retained on that surface. Spray retention can also be facilitated by adhesion of surfactant molecules in a spray droplet to the foliar surface, which in most plants is waxy and hydrophobic. This adhesion reduces not only rebound but also run-off of spray droplets from the foliar surface. Surfactants also tend to increase the area of contact between a spray droplet and a foliar surface, and in many cases enhance penetration of an exogenous chemical substance from the droplet into and through cuticles of leaves to reach internal leaf tissues.
Thr
Brinker Ronald J.
Dyszlewski Andrew D.
Gillespie Jane L.
Jones Claude R.
Kramer Richard M.
Clardy S. Mark
Finkelstein Ira D.
Forbes James C.
Howrey Simon Arnold & White
Monsanto Company
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