US 4,470,843 AGrant
Dihalopropyl Ester Herbicide Antidotes
Issue Date:1984-09-11
•19 Claims
Abstract
Herbicide antidote compounds having the formula ##STR1## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine and iodine; and R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; halophenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine; and substituted alkoxy carbonyl wherein the alkoxy group has 1-8 carbon atoms, inclusive and the substituents are halogen selected from the group consisting of chlorine, fluorine, and iodine; or dioxane.
Metadata
Assignee
- Stauffer Chemical Company
Inventor
- Kent E. Matsumoto
Application Information
Application Number:US 1962272
Filing Date:1980-10-14
Priority Date:1980-10-14
Art Unit:129
Classifications
IPC:
A01N 2532
Field of Search:
71106;100
Patent Drawings
This patent does not have any drawings.
Description
FIELD OF THE INVENTION
This invention relates to herbicide antidotes, and, more particularly, to dihalopropyl ester compounds which are useful as herbicide antidotes.
BACKGROUND OF THE INVENTION
An herbicide is a compound which adversely controls or modifies plant growth, e.g., killing, retarding, defoliating, desiccating, regulating, stunting, tillering, stimulating, and dwarfing. The term "plant" refers to all physical parts of a plant, including seeds, seedlings, saplings, roots, tubers, stems, stalks, foliage, and fruits. "Plant growth" includes all phases of development from seed germination to natural or induced cessation of life.
Herbicides are generally used to control or eradicate weed pests. They have gained a high degree of commercial success because it has been shown that such control can increase crop yield and reduce harvesting costs.
The most popular methods of herbicide application include: pre-plant incorporation into the soil; in-furrow application to seeds and surrounding soil; pre-emergence surface treatment of seeded soil; and post-emergence treatment of the plant and soil.
A manufacturer of an herbicide generally recommends a range of application rates and concentrations calculated to maximize weed control. The range of rates varies from approximately 0.01 to 50 pounds per acre (0.0111 to 56 kilograms per hectare (k/ha)), and is usually in the range of from 0.1 to 25 pounds per acre (0.112 to 28 k/ha). The term "herbicidally effective amount" describes the amount of an herbicide compound which controls or modifies plant growth. The actual amount used depends upon several considerations, including particular weed susceptibility and overall cost limitations.
The most important factor influencing the usefulness of a given herbicide is its selectivity towards crops. In some cases, a beneficial crop is susceptible to the effects of the herbicide. In addition, certain herbicidal compounds are phytotoxic to some weed species but not to others. To be effective, an herbicide must cause minimal damage (preferably no damage) to the beneficial crop while maximizing damage to weed species which plague that crop.
To preserve the benefical aspects of herbicide use and to minimize crop damage, many herbicide antidotes have been prepared. These antidotes reduce or eliminate damage to the crop without substantially impairing the damaging effect of the herbicide on weed species. See U.S. Pat. Nos. 4,021,224 and 4,021,229 and Belgian Pat. No. 846,894.
The precise mechanism by which an antidote reduces herbicidal crop injury has not been established. An antidote compound may be a remedy, interferent, protectant, or antagonist. As used herein, "antidote" describes a compound which has the effect of establishing herbicide selectivity, i.e., continued herbicidal phytotoxicity to weed species and reduced or non-phytotoxicity to cultivated crop species. The term "antidotally effective amount" describes the amount of an antidote compound which counteracts a phytotoxic response of a benefical crop to an herbicide.
Thiocarbamate herbicides are particularly effective in the control of grassy type weeds which interfere with the cultivation of a wide variety of crops, e.g., barley, corn, lentils, peanuts, peas, potatoes, soybeans, spinach, tobacco and tomatoes. Frequently the effective use of these herbicides requires the addition of an antidote compound.
DESCRIPTION OF THE INVENTION
It has now been discovered that certain dihalopropyl ester compounds are effective antidotes for the protection of a variety of crops from thiocarbamate herbicide injuries. Such compounds have the following formula: ##STR2## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine, and iodine; and
R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; halophenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine; and substituted alkoxy carbonyl wherein the alkoxy group has 1-8 carbon atoms, inclusive and the substituents are halogen selected from the group consisting of chlorine, bromine and iodine; or dioxane.
All carbon ranges are inclusive of both upper and lower limits. Exemplary of alkyl are methyl, ethyl, n-propyl, isopropyl and the like; exemplary of alkoxy are methoxy, ethoxy, and the like.
In a preferred embodiment, X and X' are both chlorine and R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; chloroethoxyethoxycarbonyl; chlorophenyl; (1-chloroethoxy-2-chloromethyl) ethoxy carbonyl; (1-chloroethoxyethoxy-2-chloromethyl) ethoxy carbonyl; and 1,4-dioxane methoxy carbonyl.
This invention also embodies a two-part herbicidal system comprised of
(a) an herbicidally effective amount of a thiocarbamate compound of the formula ##STR3## in which R.sub.1 is alkyl having 1-6 carbon atoms, inclusive;
R.sub.2 is selected from the group consisting of alkyl having 1-6 carbon atoms, inclusive; and cyclohexyl; or
R.sub.1 and R.sub.2 form indistinguishable parts of a single alkylene ring having 4-10 carbon atoms, inclusive; and
R.sub.3 is selected from the group consisting of alkyl having 1-6 carbon atoms, inclusive; haloalkyl wherein halo is selected from the group consisting of chlorine, bromine and iodine and alkyl has 1-6 carbon atoms, inclusive; alkenyl having 2-6 carbon atoms, inclusive; halo alkenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine and alkenyl has 2-6 carbon atoms, inclusive; benzyl; and halo-substituted benzyl, wherein halo is selected from the group consisting of chlorine, bromine and iodine; and
(b) a non-phytotoxic antidotally effective amount of a compound of the formula ##STR4## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine and iodine; and
R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; halophenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine; and substituted alkoxy carbonyl wherein the alkoxy group has 1-8 carbon atoms, inclusive and the substituents are halogen selected from the group consisting of chlorine, bromine and iodine; or dioxane.
By way of exemplification, the active thiocarbamate herbicides employed in the invention may include the following: S-ethyl dipropyl thiocarbamate, S-ethyl diisobutyl thiocarbamate, S-propyl dipropyl thiocarbamate, S-propyl butylethylthiocarbamate, S-(2,3,3-trichloroallyl)diisopropyl thiocarbamate, S-ethyl N-ethyl N-cyclohexyl thiocarbamate, S-ethyl hexahydro-1H-azepine-1-carbothioate, isopropyl-1-hexahydro-1,4-azepine-1-carbothioate, S-benzyl N,N-disec-butylthiolcarbamate, S-(4-chlorobenzyl) N,N-diethyl thiolcarbamate and combinations thereof.
This invention also includes the method of establishing herbicidal selectivity which comprises applying to the locus where protection is desired an antidotally effective amount of a compound of the formula ##STR5## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine and iodine; and
R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; halophenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine; and substituted alkoxy carbonyl wherein the alkoxy group has 1-8 carbon atoms, inclusive and the substituents are halogen selected from the group consisting of chlorine, bromine and iodine; or dioxane.
The locus where selectivity is desired may include soil, seeds, seedlings and vegetation.
Preparation
The thiocarbamates of the present composition are either commercially available or can be prepared by the procedures described in U.S. Pat. Nos. 2,913,327, 2,983,747, 3,133,947, 3,185,720 and 3,198,786.
The dihalopropyl ester antidote compounds of this invention can be prepared according to the following general procedure, depending upon the starting materials. 1,3-di-halo-2-propanol is reacted with an appropriate carbonyl chloride in a suitable solvent. Suitable solvent solutions include combinations of a basic component and a standard organic solvent. The basic component may be selected from the group consisting of a tertiary amine, an aromatic nitrogen, hydroxide, carbonate or bicarbonate. The standard organic solvent may be selected from the group consisting of hexane, dichloromethane, and other hydrocarbon, halocarbon, aromatic, ether and ketonic solvents. The preferred temperature range is between 0.degree. and 40.degree. C. After continuous stirring, the dihalopropyl ester may be extracted, dried, filtered and stripped. Structure may be confirmed by infrared (IR), nuclear magnetic resonance (NMR), or mass (MS) spectroscopy.
The following examples illustrate the preparation of specific compounds according to this general method. (Compound numbers correspond to those in Tables I, IV and V).
EXAMPLE 1
(Compound No. 1)
Preparation of 1,3-Dichloroprop-2-yl acetate
Seventy-five grams (g) (0.581 mole) of 1,3-dichloro-2-propanol, 58.8 g (0.581 mole) of triethylamine, and 150 milliliters (ml) of hexane were combined in a reaction flask.
Forty-five and six-tenths grams (0.581 mole) of acetyl chloride were added to the reaction mixture through a drop funnel. During the period of acetyl chloride addition the reaction mixture was stirred constantly, the mixture was maintained under an argon atmosphere, and the temperature was maintained below 20.degree. C. The mixture was stirred for 65 minutes.
The solution was filtered to remove hydrochloride. The hydrochloride was washed with benzene to remove excess 1,3-dichloroprop-2-yl acetate. The hexane extracts and the clear reaction solution were combined and washed with sodium carbonate, hydrochloric acid and water. The resulting solution was dried over magnesium sulfate, filtered, and stripped. The yield was 81.6 g 1,3-dichloroprop-2-yl acetate. Structure was confirmed by IR and NMR. (n.sub.D.sup.30 =1.4531).
EXAMPLE 2
(Compound No. 6)
Preparation of 1-(1,4-dioxanemethyl)-2-(1,3-dichloro-2-propyl)oxalate
One g (0.008 mole) of 1,3-dichloro-2-propanol, 0.9 g (0.009 mole) of triethylamine, and 50 ml of dichloromethane were combined in a reaction flask. Two and three tenths g (0.0088 mole) of 80% 1,4-dioxane-2-methyloxalyl chloride and 50 ml dichloromethane were added through a drop funnel. During the addition, the mixture was maintained under a nitrogen atmosphere, and the temperature was maintained below 20.degree. C. The mixture was stirred overnight.
The mixture was washed with water, hydrochloric acid and sodium carbonate, dried over magnesium sulfate and stripped. The yield was 2.4 g 1-(1,4-dioxanemethyl)-2-(1,3-dichloro-2-propyl) oxalate. Structure was confirmed by MS and NMR. (n.sub.D.sup.30 =1.4841).
The compounds prepared according to these procedures appear in Table I.
Testing
Stock solutions of the herbicides were prepared by diluting the requisite amount of each herbicide in water. Examples of solution compositions and application rates are summarized in Table II.
In each case, the herbicide was incorporated into the soil prior to planting. In some cases the herbicide was incorporated into the soil alone in preparation for in-furrow application of the antidode; in others the herbicide solution was tank-mixed with the antidote solution prior to incorporation.
Stock solutions of each antidote compound were prepared at the desired concentrations by diluting the requisite amounts of each antidote in acetone. Examples of solution compositions, rates and application methods are summarized in Table III.
The antidote solutions were applied to the soil either by in-furrow surface application or by pre-plant incorporation. In all cases of pre-plant incorporation, the antidote was tank-mixed with the herbicide prior to incorporation into the soil.
For in-furrow application, a one pint (473 cubic centimeter (cc)) sample of soil containing the previously incorporated herbicide was removed and retained from each planting flat. After leveling and furrowing the soil, seeds of the crop or weed species were planted 1/2 inch deep (1.27 centimeter). Each flat was divided in half by a wooden barrier. A stock solution of the antidote was atomized directly onto the exposed seeds and soil in the open furrow on one side of the barrier. The seeds in the entire flat were then covered with the previously removed soil. The antidotally untreated sections of flats were compared for observed differences which would indicate lateral movement of the antidote through the soil.
Control flats contained crops treated with herbicide only.
All flats were placed on greenhouse benches where temperature was maintained between 70.degree. and 90.degree. F. (21.1.degree. to 32.2.degree. C.). The flats were watered by sprinkling as needed to assure good plant growth.
All of the soil used in the tests described herein was loamy sand soil treated with 50 parts per million (ppm) each of a commercially available fungicide, N-[(trichloromethyl)-thio]-4-cyclohexene-1,2-dicarboximide, and 18-18-18 fertilizer, which contains 18% by weight equivalent each of nitrogen, phosphorus pentoxide, and potassium oxide.
Injury ratings were taken four weeks after application of the antidote. The effectiveness of the antidote was determined by visual comparison of crop injury which occurred in the test flats to that which occurred in the control flats.
The treated crops initially screened for diminution of herbicidal injury were milo, wheat, cotton, rice, barley, corn and soybeans. Compounds which showed substantial activity were tested further. The herbicides and the most active antidote compositions were then screened on weed species. The weed species tested included watergrass (Echinochloa crusgalli), foxtail (Setaria viridis), wild oat (Avena fatua), shattercane (Sorghum bicolor) and Johnson grass (Sorghum halepense).
KEY TO TABLES IV AND V
Compound numbers in these tables correspond to the numbers and their chemical description in Table I. Compounds omitted in Table V were not tested on weed species.
Herbicides
VERNAM.RTM.--S-propyl dipropyl thiocarbamate
EPTAM.RTM.--S-ethyl dipropyl thiocarbamate
RO-NEET.RTM.--S-ethyl N-ethyl N-cyclohexyl thiocarbamate
Antidotes
Application:
IF=In-furrow surface application of antidote (soil previously treated with herbicide only)
PPI=Pre-plant incorporation of tank-mixed solution of herbicide and antidote
If no antidote was applied, the word "none" appears in the Antidote Rate column. These are the control flats for each crop. The results shown in this line are the percent injuries sustained by each of the crops when treated with the herbicide only at the rate specified.
All rates shown, for both herbicide and antidote, are in pounds per acre.
Injury Ratings
The injury to the crop (Table IV) or weeds (Table V) is shown as a percentage of damage done to the plants as compared to a conjectural evaluation of the overall undamaged state of the plants. The damage done to the plants is a function of the number of plants injured and the extent of injury to each plant. This rating is made four (4) weeks after application of the herbicide alone or of the herbicide in combination with the antidote.
An asterisk (*) in Table IV indicates that the antidote compound is active in reducing herbicidal injury to the crop.
Table V shows that the antidote compounds tested have no effect on weeds, i.e., herbicidal injury to the weeds is sustained even in the presence of an antidote compound.
Test Results
The compounds of this invention show good antidotal activity for a variety of crops. The composition of thiocarbamate herbicide and antidote compound was particularly effective for the reduction of herbicidal injury to corn crops. Use of the antidote compounds did not result in a reduction of herbicidal injury to weeds.
Formulations
A formulation is the incorporation of a formulant in a form which is directly usable on crops and weeds. As defined herein, a "formulant" is the material which is to be formulated. The formulant may be either an antidote compound alone or an herbicide and antidote composition. The purpose of the formulation is to apply the formulant to the locus where it is desired to establish herbicidal selectivity by a convenient method. The "locus" may include soil, seeds, seedlings and vegetation.
The formulations are commonly dusts, wettable powders, granules, solutions or emulsifiable concentrates.
Dusts are free-flowing powder compositions containing the formulant impregnated on a particulate carrier. The particle size of the carriers is usually in the approximate range of 30 to 50 microns. Examples of suitable carriers are talc, bentonite, diatomaceous earth, and pyrophyllite. The composition generally contains up to 50% of formulant. Anti-caking and anti-static agents may also be added. Dusts may be applied by spraying from boom and hand sprayers on airplanes.
Wettable powders are finely divided compositions comprising a particulate carrier impregnated with the formulant and additionally containing one or more surface active agents. The surface active agent promotes rapid dispersion of the powder in an aqueous medium to form stable, sprayable suspensions. A wide variety of surface active agents can be used, for example, long chain fatty alcohols and alkali metal salts of the sulfated fatty alcohols; salts of sulfonic acid; esters of long chain fatty acids; and polyhydric alcohols, in which the alcohol groups are free, omegasubstituted polyethylene glycols of relatively long chain length. A list of surface active agents suitable for use in agriculture formulations can be found in Wade Van Valkenburg, Pesticide Formulations (Marcel Dekker, Inc., N.Y., 1973) at pages 79-84.
Granules comprise the formulant impregnated on a particulate inert carrier having a particle size of about 1 to 2 millimeters (mm) in diameter. The granules can be made by spraying a solution of the formulant in a volatile solvent onto the granular carrier. Examples of suitable carriers for the preparation of granules include clay, vermiculite, sawdust, and granular carbon.
Emulsifiable concentrates consist of an oil solution of the formulant plus an emulsifying agent. Prior to use the concentrate is diluted with water to form a suspended emulsion of oil droplets. The emulsifiers used are usually a mixture of anionic and nonionic surfactants. Other additives, such as suspending agents and thickeners, may be included in the emulsifiable concentrate.
When the formulant is an antidote and herbicide composition, the proportion of antidote compound to herbicide compound generally ranges from approximately 0.001 to 30 parts by weight of the antidote compound per weight of the herbicide compound.
Formulations generally contain several additives in addition to the formulant and carrier or agent. Among these are inert ingredients, diluent carriers, organic solvents, water, oil and water, water in oil emulsions, carriers of dusts and granules, and surface active wetting, dispersing and emulsifying agents. Fertilizers, e.g., ammonium nitrate, urea and superphosphate, may be included. Aids to rooting and growth, e.g., compost, manure, humus and sand, may also be included.
Alternatively, the antidote compounds and herbicide and antidote compositions of this invention can be applied to a crop by addition of the formulant to irrigation water supplied to the field to be treated. This method of application permits the penetration of the compositions into the soil as the water is absorbed.
As another alternative, the formulant can be applied to the soil in the form of a solution in a suitable solvent. Solvents frequently used in these formulations include kerosene, fuel oil, xylene, petroleum fractions with boiling ranges above xylene and aromatic petroleum fractions rich in methylated naphthalenes. Liquid solutions, like dusts, may be applied by spraying from boom and hand sprayers on airplanes.
Claims
What is claimed:
1. A composition comprising: (a) an herbicidally effective amount of a compound of the formula ##STR12## in which R.sub.1 is alkyl having 1-6 carbon atoms, inclusive; R.sub.2 is selected from the group consisting of alkyl having 1-6 carbon atoms, inclusive; and cyclohexyl; or R.sub.1 and R.sub.2 taken with the nitrogen form a hexamethyleneimino group; and R.sub.3 is selected from the group consisting of alkyl having 1-6 carbon atoms, inclusive; haloalkyl wherein halo is selected from the group consisting of chlorine, bromine and iodine and alkyl has 1-6 carbon atoms, inclusive; alkenyl having 2-6 carbon atoms, inclusive; halo alkenyl wherien halo is selected from the group consisting of chlorine, bromine, and iodine and alkenyl has 2-6 carbon atoms, inclusive; benzyl; and halo-substituted benzyl, wherein halo is selected from the group consisting of chlorine, bromine, and iodine; and (b) a non-phytotoxic antidotally effective amount of a compound of the formula ##STR13## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine and iodine; and R is alkyl having 1-12 carbon atoms, inclusive; said antidote being antidotally effective with said herbicide.
2. A composition according to claim 1 in which X and X' are both chlorine.
3. A composition according to claim 2 wherein R is methyl.
4. A composition according to claim 2 wherein R is n-undecyl.
5. A composition according to any of claim 1, 2, 3, or 4 wherein R.sub.1, R.sub.2 and R.sub.3 are all propyl.
6. A composition according to any of claim 1, 2, 3, or 4 wherein R.sub.1 and R.sub.2 are both propyl and R.sub.3 is ethyl.
7. A composition according to any of claim 1, 2, 3, or 4 wherein R.sub.1 is cycloheyl and R.sub.2 and R.sub.3 are both ethyl.
8. A method of improving herbicidal selectivity comprising applying to the locus where herbicidal control is desired by an herbicidal effective amount of thiolcarbamate herbicide a non-phytotoxic antidotally effective amount of a compound of the formula ##STR14## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine and iodine; and R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; halophenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine; and substituted alkoxy carbonyl wherein the alkoxy group has 1-8 carbon atoms, inclusive and the substituents are halogen selected from the group consisting of chlorine, bromine and iodine, or dioxane said antidote being antidotally effective with said herbicide.
9. A method according to claim 8 in which X and X' are both chlorine.
10. A method according to claim 9 wherein R is methyl.
11. A method according to claim 9 wherein R is n-undecyl.
12. A method of establishing herbicidal selectivity comprising applying to the locus where control is desired a composition comprising: (a) an herbicidally effective amount of a thiocarbamate compound of the formula ##STR15## in which R.sub.1 is alkyl having 1-6 carbon atoms, inclusive; R.sub.2 is selected from the group consisting of alkyl having 1-6 carbon atoms, inclusive, and cyclohexyl; or R.sub.1 and R.sub.2 form indistinguishable parts of a single alkylene ring having 4-10 carbon atoms, inclusive; and R.sub.3 is selected from the group consisting of alkyl having 1-6 carbon atoms, inclusive; haloalkyl wherein halo is selected from the group consisting of chlorine, bromine and iodine and alkyl has 1-6 carbon atoms, inclusive; alkenyl having 2-6 carbon atoms, inclusive; halo alkenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine and alkenyl has 2-6 carbon atoms, inclusive; benzyl; and halo-substituted benzyl, wherein halo is selected from the group consisting of chlorine, bromine and iodine; and (b) a non-phytotoxic antidotally effective amount of a compound of the formula ##STR16## in which X and X' are halogens, independently selected from the group consisting of chlorine, bromine and iodine; and R is selected from the group consisting of alkyl having 1-12 carbon atoms, inclusive; halophenyl wherein halo is selected from the group consisting of chlorine, bromine and iodine; and substituted alkoxy carbonyl wherein the alkoxy group has 1-8 carbon atoms, inclusive and the substituents are halogen selected from the group consisting of chlorine, bromine and iodine, or dioxane said antidote being antidotally effective with said herbicide.
13. A method according to claim 12 in which X and X' are both chlorine.
14. A method according to claim 13 wherein R is methyl.
15. A method according to claim 13 wherein R is n-undecyl.
16. A composition according to any of claim 12, 13, 14, or 15 wherein R.sub.1, R.sub.2, and R.sub.3 are all propyl.
17. A composition according to any of claim 12, 13, 14, or 15 wherein R.sub.1 and R.sub.2 are both propyl and R.sub.3 is ethyl.
18. A composition according to claim 12, 13, 14, or 15 wherein R.sub.1 is cyclohexyl and R.sub.2 and R.sub.3 are both ethyl.
19. A formulation comprising an herbicidally effective amount of an herbicide selected from the group consisting of S-propyl dipropylthiocarbamate, S-ethyl dipropylthiocarbamate and S-ethyl-N-ethyl N-cyclohexylthiocarbamate and an antidotally effective amount of a compound selected from the group consisting of 1,3-dichloroprop-2-yl acetate; (1,3-dichloroisopropyl)-2-(2-chloroethoxyethoxy) oxalate; 1,3-dichloro-2-propyl-4-chlorobenzoate; 1-[1-(2-chloroethoxy)-3-chloro-2-propyl]-2-(1,3-dichloro-2-propyl) oxalate; 1-(1-<2-(2-chloroethoxy)ethoxy>)-2-(1,3-dichloro-2-propyl) oxalate; 1-(1,4-dioxanemethyl)-2-(1,3-dichloro-2-propyl) oxalate; and 2,3-di-chloropropyl laurate.
Patent Citations (1)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| US3893838 | 1975-07-01 | Pallos |
Non-Patent Literature (1)
- Pallos et al., (Ed.), Chemistry and Action of Herbicide Antidotes, p. 10, Academic Press, (1978).