US 2876088 A
Description (OCR text may contain errors)
- Gideon D.
2,876,088 PROCESS FOR CONTROLLING VEGETATION Hill and Silas S. Sharp, Wilmington, and Dale E. Wolf, Hockessin, Del., assignors to E. I. du Pont de Nemonrs and Company, Wilmington, Del., a corporation of Delaware No Drawing. Application November 26, 1954 Serial No. 471,516
2 Claims. (CI. 11-25 This invention relates to processes for the-control of weeds in soil of high adsorptivity. More particularly, it relates to methods in which both a herbicidally active aromatic aliphatic substituted urea and a high boiling hydrocarbon oil, as more specifically set out hereinafter, are applied to such soils.
Varied classes of substituted ureas are known to be useful for the control of unwanted vegetation. Some of these are set forth, for example, in U. S. Patents 2,655,444, 2,655,445, and 2,655,447. Many of the substituted ureas are highly effective in soil sterilant use for a large variety of soil types. By soil sterilant we mean a material that is effective for giving complete kill of plant growth for an extended period. There has existed a problem, however, in obtaining effective soil sterilant use of urea herbicides on soils of high adsorptivity specifically on soils having a k-value greater than about 15. Such soils exist along many railroad right-of-ways, and also in and around lumbering operations and industrial areas or parking lots having a high content of carbonaceous material such as cinders.
The term soil is used herein in its broadest sense to mean any solid substance or medium in which plants can take root and grow. In other words, it includes such varied things as railroads ballast including its contaminants, cinders, muck soils, as well as earth surface material of the more conventional kind.
The processes of the invention can be practiced with any of the herbicidally active substituted ureas. Preferably the ureas employed are those represented by the where X is hydrogen or halogen; Y is hydrogen or an aliphatic group of l to 4 carbon atoms; n is a positive integer from 1 to 4 inclusive; m is a positive integer from 1 to 3 inclusive; the sum of n and m being from 2 to 5 inclusive; R and R" are hydrogen, formyl or an aliphatic group of 1 to 4 carbon atoms; R is methyl or ethyl; with the proviso that not more than one of R and R" is formyl.
Illustrative of the preferred aromatic aliphatic ureas employed in the processes of the invention are:
3-(p-chlorophenyl)-l-methyl urea 3-(3,4-dichlorophenyl)-l,l-dimethylurea 3-(p-chlorophenyl)-1,l-dimethylurea 3-phenyl-l,l-dimethylurea 3-(3-chloro-p-tolyl)-1,l-dimethylurea 3-(3-chloro-4-sec. butylphenyl)-l,1-dimethylurea 3-( 3 ,4'dichlorophenyl) -1,1-diethylurea 3-(p-tolyl)-1,1-dimethylurea 3-(3,4-dimethylphenyl)-1,1-dimethylnrea 3-(3,4-dichlorophenyl)-l-methyll-sec. butylurea 3-(3,4-dichlorophenyl)-1-methyl-1-N-butylurea 1 (3,4-dich1orophenyl)-1,3'dimetbylurea 2 3-(p-chlorophenyl)-1,1,3-trimethylurea 3-(3,4-diehlorophenyl)-1,l,3-trimethylurea 3-(m-chlorophenyl)-1,1-dimethylurea 3-(2,4,5-trichlorophenyl)-l,l-dimethylurea 3-(3,4-dichlorophenyl)-3-formyl-1,1-dimethylurea 3-(3,4-dichlorophenyl)-l-formyl-1-methylurea 3-(p-chlorophenyl)-1-formy1-1-methylurea 3-(m-chlorophenyl) -1-formyll-methylurea 3-(3-chloro-4-isopropylphenyl)-1,1-dimethylurea The high boiling hydrocarbon oils employed in the processes of the invention are those generally characterized by having a boiling range of 400 to 700 F. at atmospheric pressure and an ASTM sulfonation index of not more than about by volume. Most preferred are those hydrocarbon oils having a sulfonation index of from 50 to 70%.
Illustrative of suitable high boiling hydrocarbon oils are a product currently sold under the designation of L-8764" by Standard Oil Company of Indiana, and a product currently marketed under the designation of "LHO- by Lion Oil Company.
In carrying out the processes of the invention, the substituted urea and the oil can be applied simultaneously from a mixture or solution of the urea compound and the oil or alternatively it can be applied separately in point of time, in which latter case it would ordinarily be preferable to apply the oil first.
The amounts ofoil and substituted urea applied will, of course, vary widely depending upon the particular soil type, the weed problem involved, and the particular substituted urea employed. In general, the oil will be employed in amount corresponding to at least 25 gallons per acre. Ordinarily, it is unnecessary to apply more than about 250 gallons per acre under anytcircumstances altho larger amounts can be used if cost is not a consideration. The substituted ureas will ordinarily be applied in amounts corresponding to at least 5 pounds per acre and more generally 10 pounds per acre or more with a practical economic top limit of about pounds per acre.
The urea herbicide to be applied, either separately or in admixture with the oil, can be admixed with other pest control adjuvants or conditioning materials in the conventional manners. Thus the material can be in the form of a powder, a solution, an oil suspension, or an emulsifiable composition. It will be understood also that the high boiling hydrocarbon oil uad need not be pure, that is, it may contain substantial amounts of lower or higher boiling materials as well as non-hydrocarbon such as the usual sulfur and other constaminants found in petroleum distillates.
As mentioned heretofore, the soils upon which the methods of the invention are practiced are those having a high adsorptivity, more specifically those specified as having a k-value greater than about 15. By k-value, we mean the concentration of the substituted urea compound in parts per million on the soil in equilibrium with an aqueous solution of the substituted urea in a concentration of one part per million. More specifically, k-value refers to the constant k in the Freundlich adsorption equation:
where c is the concentration in parts per million of the substituted urea in solution in equilibrium with the adsorbent, x is the quantity in micrograms of the sub stituted urea adsorbed on m grams of soil, n, like k, is a constant and is readily determined for each system by determining at least two equilibrium values of x and c and solving the above equation by conventional graphical procedures.
Methods of the invention are further illustrated by the following detailed examples.
Example 1 A high boiling hydrocarbon oil and 3-(p-chlorophenyl)' l,1-dimethylurea were applied both alone and in combination in the amounts shown in the tabulation below to a railroad ballast having a k-value of 31.
The oil employed in this example is characterized as follows:
Distillation range (ASTM method) 472-720" F.
Sulfonation index 64% by volume. Hydrogen to carbon ratio 1.62.
Refractive index 1.5108 at 25 C. Specific gravity 0.8894. Bromine number 36.8.
The following table which shows the applications of the several materials and their dosagesalso shows the measure of herbicidal action.
Urea Herb- Oil in ieide in Gallons Herbieidal Action 26 Days Pounds Per Acre After Treatment Per Acre 1 25 104. 9 substantially complete kill. 2 25 None slight to moderate injury. 3 None 104. 9 some slight injury at leaf tips.
In this experiment, the methods and materials used are the same as in Example 1 except that diesel oil replaces the oil used in that example. The results obtained are shown in the following tabulation.
Urea Herb- Oil in icide in Gallons Herbicidal Action 26 Days Pounds For Auto After Treatment For Acre 1 30 209.8 substantially complete kill. 2 30 None moderate plant in ury. 3 None 209. 8 no injury.
The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described for obvious modifications will occur to those skilled in the art. Thus any departure from the description herein which conforms to the principles of the invention is intended to be included within the scope of the claims below.
1. A process for the control of vegetation in soil having an adsorptivity equivalent to a k-value above about 15 which comprises applying to said soil at an acre rate of from about 5 to 100 pounds of a herbicidally active aromatic aliphatic urea mixed with from about 25 to 250 gallons of a hydrocarbon oil boiling in the range of 400 to 700 F. at atmospheric pressure and having a sulfonation index of no more than about by volume.
2. A process for the control of vegetation in soil having an adsorptivity equivalent to a k-value above about 15 which comprises applying to such soil one or more herbicidally active aromatic aliphatic ureas represented by the formula:
Yin-i R B."
where X is selected from the group consisting of hydrogen and halogen; Y is selected from the group consisting of hydrogen and an aliphatic group consisting of 1 to 4 carbon atoms; n is a positive integer from 1 to 4 inclusive, m is a positive integer from 1 to 3 inclusive, the sum of n and m being from 2 to 5 inclusive; R and R" are selected from the group consisting of hydrogen, formyl, and an aliphatic group of from 1 to 4 carbon atoms, with the proviso that not more than one of R and R" is formyl; and R is selected from the group consisting of methyl and ethyl; said ureas being mixed with a hydrocarbon oil boiling in the range of 400 to 700 F. at atmospheric pressure and having a sulfonation index not greater than 90% by volume, said mixture of urea and oil being applied at the rate of from about 5 to pounds of urea and from about 25 to 250 gallons of oil per acre.
References Cited in the file of this patent UNITED STATES PATENTS 2,655,446 Todd Oct. 13, 1953 2,704,246 Goodhue et a1. Mar. 15, 1955 2,732,291 Davie Jan. 24, 1956