Herbicide compositions of extended soil life

Herbicidally active thiocarbamates are employed in combination with certain unsaturated aryl sulfides, sulfoxides or sulfones having the formula ##STR1## in which R.sup.4 is hydrogen, halogen, C.sub.1 -C.sub.6 alkyl or C.sub.1 -C.sub.6 alkoxy; R.sup.5 is C.sub.2 -C.sub.6 haloalkenyl or C.sub.2 -C.sub.6 alkynyl; and n equals 0 or 2. In a typical application, the unsaturated aryl sulfide, sulfoxide or sulfone is included in sufficient quantity to lessen the rate of soil degradation of the thiocarbamate. As a result, the herbicidal effectiveness of the thiocarbamate is enhanced and prolonged, rendering a single application of the herbicide effective over a longer period of time.

BACKGROUND OF THE INVENTION 
This invention relates to herbicidal compositions, their methods of use, 
and their preparation. In particular, this invention relates to herbicidal 
compositions comprising an herbicidally active thiocarbamate in 
combination with certain unsaturated aryl sulfides, sulfoxides and 
sulfones, the latter serving to prolong the effectiveness of a single 
application of the thiocarbamate in controlling undesired plant growth. 
Many of the compounds herein disclosed are known compounds, however, one of 
the compounds herein exemplified, namely, 4-methoxyphenyl-1-propynyl 
sulfide having the formula 
##STR2## 
is a novel compound. Most of the references which have disclosed compounds 
within the generic formula of the instant invention, show their utility to 
be only as chemical intermediates in various syntheses. Martin et al., 
U.S. Pat. No. 3,777,024, discloses some aryl propargyl sulfides as 
insecticidal synergists, and Martin et al., South African Pat. No. 28,150, 
discloses such compounds as endo- and ectoparasiticides. Neither patent 
discloses such compounds in combination with thiocarbamate herbicides, or 
as having any soil extender properties for any herbicides. 
Thiocarbamates are well known in the agricultural art as herbicides useful 
for weed control in crops such as corn, potatoes, beans, beets, spinach, 
tobacco, tomatoes, alfalfa, rice and others. Thiocarbamates are primarily 
used in pre-emergence application, and are particularly effective when 
incorporated into the soil prior to the planting of the crop. The 
concentration of the thiocarbamate in the soil is greatest immediately 
after application of the compound. How long thereafter the initial 
concentration is retained depends in large part on the particular soil 
used. The rate at which the thiocarbamate concentration declines following 
its application varies from one type of soil to the next. This is evident 
both in the observable extent of weed control and in the detectable 
presence of undegraded thiocarbamate remaining in the soil after 
considerable time has elapsed. 
It is therefore an object of this invention to increase the soil 
persistence of thiocarbamate herbicides and thus improve their herbicidal 
effectiveness. 
BRIEF DESCRIPTION OF THE INVENTION 
It has now been discovered that the soil persistence of certain 
herbicidally active thiocarbamates is significantly extended by the 
further addition to the soil of certain extender compounds in the form of 
certain unsaturated aryl sulfides, sulfoxides and sulfones, which have 
little or no herbicidal activity of their own and do not decrease the 
herbicidal activity of the thiocarbamate. This improvement in the soil 
persistence of thiocarbamates manifests itself in a variety of ways. It 
can be shown, for example, by soil analyses taken at regular intervals, 
that the rate of decrease of the thiocarbamate content of the soil is 
substantially lessened. However, more preferably, improved soil 
persistence can also be shown by improvements in herbicidal efficacy, as 
evidenced by a higher degree of weed injury brought about when the 
extender compound increases the soil persistence of the thiocarbamate, 
prolonging its effective life. 
In particular, this invention relates to novel herbicidal compositions 
comprising 
(a) an herbicidally effective amount of a thiocarbamate having the formula 
##STR3## 
in which R.sup.1 is C.sub.1 -C.sub.6 alkyl or C.sub.3 -C.sub.6 alkenyl, 
optionally substituted with one, two or three halogen atoms; and R.sup.2 
and R.sup.3 are either selected independently from C.sub.1 -C.sub.6 alkyl 
or combined to conjointly form C.sub.4 -C.sub.7 alkylene; and 
(b) an amount of an unsaturated aryl sulfide, sulfoxide or sulfone 
sufficient to extend the soil life of said thiocarbamate, said sulfide, 
sulfoxide or sulfone having the formula 
##STR4## 
in which 
R.sup.4 is hydrogen, halogen, C.sub.1 -C.sub.6 alkyl or C.sub.1 -C.sub.6 
alkoxy; 
R.sup.5 is C.sub.3 -C.sub.6 haloalkenyl or C.sub.2 -C.sub.6 alkynyl; and n 
is 0, 1 or 2. 
Within the scope of the present invention, the following embodiments are 
preferred, namely: 
in the thiocarbamate formula, R.sup.1, R.sup.2 and R.sup.3 are preferably 
C.sub.2 -C.sub.4 alkyl, and most preferably R.sup.1 is ethyl and R.sup.2 
and R.sup.3 are each propyl; and 
in the sulfide, sulfoxide or sulfone formula, R.sup.4 is preferably 
hydrogen, halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy; 
R.sup.5 is preferably C.sub.3 -C.sub.4 haloalkenyl or C.sub.3 -C.sub.4 
alkynyl; and n is 0 or 2. More preferably, R.sup.4 is hydrogen, methyl, 
methoxy or halogen; R.sup.5 is propynyl, propargyl or haloallyl; and most 
preferably R.sup.4 is hydrogen, methyl or halogen, R.sup.5 is propynyl or 
propargyl and n is 0. 
This invention also relates to a method of controlling undesirable 
vegetation comprising applying the above composition to the locus where 
control is desired. 
This invention further relates to a novel dehydrohalogenation process for 
preparing the aryl alkynyl sulfide extender compounds disclosed herein. 
The term "alkyl" is used herein in its normal meaning and is intended to 
include both straight-chain and branched-chain groups. 
The term "herbicide", as used herein, means a compound or composition which 
adversely controls or modifies the growth of plants. By the term 
"herbicidally effective amount" is meant any amount of such compound or 
composition which adversely causes a modifying effect upon the growth of 
plants. By "plants" is meant germinant seeds, emerging seedlings and 
established vegetation, including roots and above-ground portions. Such 
adverse controlling or modifying effects include all deviations from 
natural development, such as killing, retardation, defoliation, 
desiccation, regulation, stunting, tillering, stimulation, leaf burn, 
dwarfing and the like. 
The phrase "to extend the soil life of said thiocarbamate" as used herein 
means to retard the rate at which molecules of thiocarbamate are broken 
down into decomposition products when in contact with soil and/or to 
prolong the period of time following application in which herbicidal 
effects can be observed. This applies both to field sites where repeated 
applications of thiocarbamates have resulted in decreasing herbicidal 
effectiveness, and to field sites where a decline in activity is detected 
over time regardless of the prior history of herbicidal applications. An 
extended soil life can be manifested in a slower rate of decline of 
weed-killing activity, or an increased half-life of thiocarbamate 
concentration in the soil. Other techniques of determining soil life are 
readily apparent to one skilled in the art. 
DETAILED DESCRIPTION OF THE INVENTION 
According to the present invention, the above-described unsaturated aryl 
sulfides, sulfoxides or sulfones are applied to prolong the molecular 
integrity and herbicidal effectiveness of the thiocarbamates. As the 
examples below indicate, there is no critical range of the ratio of these 
two components. The soil life-extending effect is observable over a broad 
range of ratios. It is most convenient, however, to apply the compounds at 
a ratio of from about 0.2:1 to about 15:1 (thiocarbamate:unsaturated aryl 
sulfide, sulfoxide or sulfone). Preferably, the ratio ranges from about 
0.5:1 to about 8:1, and most preferably from about 0.5:1 to about 6.5:1. 
Thiocarbamates which are useful in the present invention inlcude S-ethyl 
N,N-dipropyl thiocarbamate, S-ethyl N,N-diisobutyl thiocarbamate, S-propyl 
N,N-dipropyl thiocarbamate, S-propyl N,N-butylethyl thiocarbamate, 
S-2,3,3-trichloroallyl diisopropyl thiocarbamate, S-2,3-dichloroallyl 
diisopropyl thiocarbamate and S-ethyl-hexahydro-1H-azepine-1-carbothioate. 
The thiocarbamates within the scope of the present invention can be 
prepared by the process described in U.S. Pat. No. 2,913,327 (Tilles et 
al., Nov. 17, 1959) or U.S. Pat. No. 3,330,643 (Harman et al., July 11, 
1967). 
The unsaturated aryl sulfides, sulfoxides and sulfones which are useful in 
the present invention include 4-propargylthio-chlorobenzene (Compound 1); 
4-chlorophenyl propargyl (Compound 2); para-chlorophenyl-1-propynyl 
sulfide (Compound 3); phenyl-1-propynylsulfide (Compound 4); 
1-phenylsulfonyl-1-propyne (Compound 5); 2-chloroallyl-4-methylphenyl 
sulfide (Compound 6); 2-chloroallyl-4-methoxyphenyl sulfide (Compound 7); 
4-methylphenyl-1-propynyl sulfide (Compound 8); and 
4-methoxyphenyl-1-propynylsulfide (Compound 9). 
The extender compounds claimed herein can be prepared by a variety of known 
techniques, for example, by methods described in the following references: 
Andersen, W. K. et al., Synthesis of 2-Methylbenzo[b]furans and 
2-Methylbenzo[b]thiophens, J.C.S. Chem. Comm. 1974 (5), p. 174; Nakajima 
et al., U.S. Pat. No. 3,772,023; Iddon B. et al., Adv. Heterocyclic Chem., 
1970 (11) p. 177; Truce, W. E. et al., Sterochemistry of Amine Additions 
to Acetylenic Sulfones, J. Org. Chem. 1975 (40) p. 3200 (at 3250); 
Andersen, W. K. et al., Use of 2,3-Dichloropropene and 
1,3-Dichlorobut-2-ene as Synthons for Heterocyclic Compounds. Synthesis of 
2-Methylbenzo[b]furans, 2-Methyl-benzo[b]thiophens, and 
4-Methyl-2H-chromen, J. Chem. Soc. 1976 (1) 1; Hill, C. J. et al., The 
Mass Spectral Rearrangements of Aryl Propenyl Sulfones. An Electron Impact 
Induced Smiles Type Rearrangement, Org. Mass. Spec., 1977 (12) p. 379; and 
Martin et al., U.S. Pat. No. 3,777,024. 
In broad outline, the aryl haloalkenyl sulfides can be prepared by 
combining dihalo-alkenes with an appropriately substituted thiophenol in 
the presence of a base such as potassium carbonate, triethylamine, sodium 
hydroxide or an alkoxide. 
The aryl alkynyl sulfides of the instant invention can be prepared by the 
dehydrohalogenation of appropriate aryl haloalkenyl sulfides. A strong 
base is required for the reaction, preferably an alkali metal salt of an 
amine, ammonia, an alkoxide or an hydroxide. The latter is a novel and 
preferred base. The most preferred base is an aqueous solution of from 
40-60% sodium hydroxide, with a more preferred solution range being from 
45-55% and the most preferred concentration being 50%. The use of such a 
base is novel, economical and aids in phase separation. 
The dehydrohalogenation reaction is run in a mixed phase system with a 
phase transfer catalyst, such as benzyl triethyl ammonium chloride, 
tetrabutyl phosphonium bromide, tetrabutyl ammonium bromide, or 
Aliquot.RTM. 336 (tricaprylyl methyl ammonium chloride). In general, an 
inert solvent, such as tetrahydrofuran (THF), ether, benzene, or toluene 
is employed. Where an hydroxide salt is used in the reaction, the solvent 
can be methylene chloride or 1,1,2-trichlorethane. 
The preferred temperature for such a process is between -30.degree. C. and 
150.degree. C. A more preferred temperature range for such a reaction is 
from 0.degree. C. to 110.degree. C., and the most preferred temperature 
range is from 20.degree. C. to 45.degree. C. 
Such a reaction is illustrated by the example below of the preparation of 
the novel compound 4-methoxyphenyl-1-propynyl sulfide. 
Preparation of 4-Methoxyphenyl-1-propynyl sulfide 
Seven and two-tenths grams (7.2 g; 0.034 mole) of para-methoxyphenyl 
2-chloroallyl sulfide was combined with 10 milliliters (ml) of 50% NaOH 
solution (0.087 mole), 0.5 g of the phase transfer catalyst tetrabutyl 
phosphonium bromide, and 5 ml of the inert solvent methylene chloride. The 
mixture was stirred and then allowed to stand at room temperature over the 
weekend. Standard work-up procedures were employed. 
The yield was 4.8 g. The expected product was confirmed by NMR (nuclear 
magnetic resonance), IR (infrared refraction) and MS (mass spectroscopy). 
Preparation of 4-Methylphenyl-1-propynyl sulfide 
Six and nine-tenths grams (6.9 g) of para-methylphenyl 2-chloroallyl 
sulfide was combined with 10 ml of 50% NaOH solution, 0.5 g of the phase 
transfer catalyst tetrabutyl phosphonium bromide, and 5 ml of the inert 
solvent methylene chloride. The mixture was stirred and then allowed to 
stand at room temperature over the weekend. Standard work-up procedures 
were employed. 
The yield was 4.8 g. The expected product was confirmed by both NMR, IR and 
MS. 
Different types of aryl alkynyl sulfides can be prepared by rearrangement 
of the triple bond. (See for example, Pourcelot, G. et al., Cinetique et 
Mecanisme da la Reaction de Prototropic des Composes Propargyliques, 
Alleniques et Propynyliques Portant un Heteroatome (Colonne Vb et VIb), 
Tetrahedron 1982 (38) p. 2123.) 
The aryl unsaturated sulfoxides and sulfones claimed herein can be prepared 
from the corresponding sulfides by oxidation with one or two equivalents 
of meta-chloro perbenzoic acid, respectively. 
The objects of the present invention are achieved by applying the 
unsaturated aryl sulfide and sulfone extender compounds to the soil at an 
agricultural field site in conjunction with the thiocarbamate herbicide. 
The extender and herbicide can be applied simultaneously in a single 
mixture or in separate formulations, or they can be applied in succession, 
with either one following the other. In successive application, it is 
preferable to add the compounds as close in time as possible. 
The variety of crops on which the present composition is useful can be 
significantly broadened by the use of an antidote to protect the crop from 
injury and render the composition more selective against weeds. 
For antidote descriptions and methods of use, reference is made to U.S. 
Pat. No. 3,959,304 issued to E. G. Teach on May 25, 1976; U.S. Pat. No. 
3,989,503 issued to F. M. Pallos et al. on Nov. 2, 1976; U.S. Pat. No. 
4,021,224 issued to F. M. Pallos et al. on May 3, 1977; U.S. Pat. No. 
3,131,509 issued to O. L. Hoffman on May 5, 1964; and U.S. Pat. No. 
3,564,768 issued to O. L. Hoffman on Feb. 3, 1971. 
Useful antidotes include acetamides having the formula 
##STR5## 
in which m is 1 or 2, and R.sup.6 and R.sup.7 are independently C.sub.1 
-C.sub.12 alkyl or C.sub.2 -C.sub.12 alkenyl. Examples falling within the 
above formula are N,N-diallyl dichloroacetamide and N,N-diallyl 
chloroacetamide. 
Further useful antidotes are oxazolidines and thiazolidines having the 
formula 
##STR6## 
in which R.sup.9 is C.sub.1 -C.sub.4 alkyl, haloalkyl, or dihaloalkyl, 
R.sup.9 through R.sup.14 are independently hydrogen or methyl, and X is 
oxygen or sulfur. An example of such an antidote is 
2,2,5-trimethyl-N-dichloroacetyl oxazolidine (R.sup.8 .dbd.CHCl.sub.2, 
R.sup.9 .dbd.R.sup.10 .dbd.R.sup.11 .dbd.H, R.sup.12 .dbd.R.sup.13 
.dbd.R.sup.14 .dbd.CH.sub.3, X.dbd.O). 
Other useful antidotes include 1,8-naphthalic anhydride and 
2,2-spiro-cyclohexane-N-dichloroacetyl oxazolidine. 
For maximum effect, the antidote is present in a non-phytotoxic, 
antidotally effective amount. By "non-phytotoxic" is meant an amount which 
causes at most minor injury to the crop. By "antidotally effective" is 
meant an amount which substantially decreases the extent of injury caused 
by the herbicide to the crop. The preferred weight ratio of herbicide to 
the crop is about 0.1:1 to about 30:1. The most preferred range for this 
ratio is about 3:1 to about 20:1. 
The extender compounds for which test results are recorded below are as 
follows: 
TABLE I 
______________________________________ 
Extender 
Compound 
No. Structure Name 
______________________________________ 
##STR7## 4-propargylthio- chlorobenzene 
2 
##STR8## 4-chlorophenyl propargyl sulfone 
3 
##STR9## p-chlorophenyl 1-propynyl sulfide 
4 
##STR10## phenyl-1-propynyl sulfide 
5 
##STR11## 1-phenyl sulfonyl- 1-propyne 
6 
##STR12## 2-chloroallyl-4- methylphenyl sulfide 
7 
##STR13## 2-chloroallyl-4- methoxyphenyl sulfide 
8 
##STR14## 4-methylphenyl-1- propynyl sulfide 
9 
##STR15## 4-methoxyphenyl- 1-propynyl 
______________________________________ 
sulfide 
The following examples are offered to illustrate the utility of the present 
invention, and are intended neither to limit nor define the invention in 
any manner.

EXAMPLE 1 
Herbicidal Activity Improvement Tests 
This example offers herbicidal activity test data for the abovereferenced 
compounds to show the effectiveness of the range of extender compounds of 
the instant invention in improving the herbicidal activity of 
thiocarbamates. The effect is observed by comparing the extent of weed 
control in test flats treated with a thiocarbamate against that occurring 
in similar flats treated with both the thiocarbamate and the extender. The 
soil used in these tests was a sandy loam soil from Sunol, Calif., which 
was pre-treated with the herbicide to simulate a typical field which had 
received previous herbicide applications. 
A. Soil Pre-Treatment 
A solution was prepared by diluting an emulsifiable liquid concentrate 
containing 6 lb/gal (0.72 kg/l) (76.8% by weight) of the herbicide S-ethyl 
di-n-propylthiocarbamate in 200 ml of water, such that the resulting 
concentration of herbicide in the solution was 2000 mg/l. Two hundred ml 
of this solution was then added to 200 lb (90.8 kg) of soil to which 
17-17-17 fertilizer (N-P.sub.2 O.sub.5 -K.sub.2 0 on a weight basis) had 
been previously added to a concentration of 50 ppm by weight with respect 
to the soil. The mixture was mixed in a rotary mixer for 10 to 30 minutes. 
The soil was then placed in round plastic containers, 7.5 inches (19.0 cm) 
in diameter by 7.5 inches (19.0 cm) deep. The soil was tamped and leveled 
with a row marker to impress three rows across the width of each 
container. One row was seeded with DeKalb XL-45A corn (Zea mays), and two 
rows were seeded with barnyardgrass (Echinochloa crusqualli). Sufficient 
seeds were planted to produce several seedlings per row. The containers 
were then placed in a greenhouse maintained at 20.degree. C. to 30.degree. 
C. and watered daily by sprinkler. 
Five weeks after treatment, the soil was allowed to dry out and the plant 
foliage was removed. The soil was then passed through a 0.25 inch (0.64 
cm) screen to remove plant roots and clods. 
B. Herbicide Test 
The same thiocarbamate preparation described in Part A was used. The 
extender compounds were used in technical form. These materials were added 
to 100 cc mixtures of equal parts of water and acetone at such amounts 
that 5 cc of the resulting mixture when added to three pounds of soil 
yielded a quantity in the soil equivalent to the desired application rate 
expressed in pounds per acre. Thus 5 cc of the mixture and three pounds of 
soil were placed in a rotary mixer. 
The treated soil was then placed in aluminum flats which were approximately 
3 inches deep, 4 inches wide, and 8 inches long (7.6.times.10.2.times.20.3 
cm). The soil was tamped and leveled with a row marker to impress six rows 
across the width of the flat. The test weeds were as follows: 
______________________________________ 
COMMON ABBREVI- 
NAME ATION SCIENTIFIC NAME 
______________________________________ 
watergrass 
WG Echinochloa crusgalli (L.) 
wild oats WO Avena fatua (L.) 
wild cane WC Sorghum bicolor (L.) Moench 
yellow foxtail 
YF Setaria lutescens (Weigle) Hubb. 
annual ryegrass 
AR Lolium temulentum 
______________________________________ 
Rox orange and R-10 milo (both Sorghum bicolor) were also used in some of 
the experiments as a plant growth indicators. 
DeKalb XL-45A or XL-25A corn of species Zea mays (L.) was also planted. 
Sufficient seeds were planted to produce several seedlings per inch in each 
row. The flats were then placed in a greenhouse maintained at 70.degree. 
to 85.degree. F. (21.degree. to 30.degree. C.) and watered daily by 
sprinkler. 
Approximately three weeks after treatment, the degree of weed control and 
corn injury were estimated and recorded as a percentage compared to the 
growth of the same species in a check flat of the same age which had been 
seeded in conditioned soil but not treated with either an herbicide or an 
extender. The rating scale ranges from 0 to 100%, where 0 equals no effect 
with plant growth equal to the untreated check, and 100 equals complete 
kill. 
The results are listed in Table I. Each alphabetized test represents a 
separate batch of experiments. Control experiments (herbicide alone with 
no extender present) were included in each batch for comparison. 
Substantial improvements in average percent weed control over the control 
experiments are evident. The herbicidal efficacy of the thiocarbamate 
three weeks after application was much improved by the use of the 
extender, whereas the corn remained unaffected. 
TABLE II 
__________________________________________________________________________ 
HERBICIDE TEST RESULTS 
HERBICIDE: S--Ethyl, N,N--dipropylthiocarbamate (EPTC) at 3 lb/A 
EXTENDER: Indicated by Compound Numbers in Table I; application rates are 
shown in Table. 
Extender Percent Injury 
Test 
Cmpd. Rate 
Water- 
R-10 
Wild 
Wild 
Annual 
Yellow 
Rox Ave. % 
No. 
No. (lb/A) 
grass 
Milo 
Oats 
cane 
rye foxtail 
orange 
Corn 
Control 
__________________________________________________________________________ 
A Control* 
-- 0 0 0 0 0 NT NT 0 0 
A 4 2 50 80 50 40 100 NT NT 0 64 
A 4 4 85 95 80 80 100 NT NT 0 88 
B Control* 
-- 0 0 0 0 NT 0 NT 0 0 
B 2 4 15 60 30 0 NT 0 NT 0 21 
B 3 4 65 80 70 70 NT 10 NT 0 59 
C Control* 
-- 0 0 0 NT 0 NT 0 0 0 
C 1 2 20 85 10 NT 85 NT 85 0 57 
C 1 4 65 85 75 NT 95 NT 90 0 82 
D Control* 
-- 23 35 38 0 NT 0 NT 0 19 
D 6 4 65 70 90 45 NT 40 NT 0 62 
D 7 4 30 65 75 10 NT 10 NT 0 38 
D 8 4 70 85 75 85 NT 40 NT 0 71 
D 9 4 80 70 80 25 NT 20 NT 0 55 
E Control* 
-- 20 15 70 15 NT 10 NT 0 26 
E 6 1 20 20 80 40 NT 10 NT 0 34 
E 6 2 30 40 90 60 NT 10 NT 0 46 
E 6 3 50 40 85 85 NT 40 NT 0 60 
F Control** 
-- 0*** 
23 26 0 NT NT NT 0 12 
F 5 2 35*** 
40 50 30 NT NT NT 0 39 
F 5 4 68*** 
70 70 40 NT NT NT 0 62 
__________________________________________________________________________ 
NT = Not Tested 
*Control Data average of two replications. 
**Control Data average of three replications. 
***Average of two rows of watergrass. 
EXAMPLE 2 
Chemical Assay Data 
These examples show, by soil analysis, the effectiveness of the compounds 
of the present invention in extending the soil life of the thiocarbamate 
herbicides. The herbicide used in these tests was the same as in Example 
1, S-ethyl N,N-dipropyl thiocarbamate (EPTC). The soil was a silty loam 
soil obtained from Mississippi, containing approximately (on a weight 
basis) 65.2% sand, 31.8% silt, and 3.0% clay, determined by mechanical 
means. The total organic content of the soil was approximately 0.1% by 
weight and the pH was 8.1, both determined by chemical analysis. 
A. Soil Pre-Treatment 
The soil was pre-treated according to the procedure outlined in Part A of 
Example 1, except that the soil at the end of the procedure is passed 
through a two millimeter (mm) screen. 
B. Soil Persistence Test 
A 100-gram quantity (air-dry basis) of the pre-treated soil was placed in 
an 8 ounce (0.25 liter) wide-mouth glass bottle. The same emulsifiable 
concentrate described in Part A above was appropriately diluted in water 
such that a 5-ml portion added to the soil would produce a herbicide 
concentration of 6 ppm (weight) in the soil. This is equivalent to an 
application rate of 6 pounds per acre (6.7 kilograms per hectare) in a 
field where the herbicide is incorporated into the soil through a depth of 
about 2 inches (5.08 cm) soon after application. A selected extender 
compound in tehcnical (nonformulated) form was then diluted in an 
acetonewater mixture such that a one-ml portion added to the soil would 
produce a concentration of 4 ppm by weight, equivalent to 4 pounds per 
acre (4.5 kilograms per hectare). On these bases, the herbicide and 
extender were added to the bottle containing the soil. 
Following such treatment, the soil was moistened with 20 ml deionized 
water. The bottle was then covered with a watch glass to maintain aerobic 
conditions and to prevent rapid soil drying, and placed in a controlled 
environmental chamber in darkness, where the temperature was maintained 
constant at 25.degree. C. 
Four days later, the bottle was removed from the environmental chamber and 
25 ml of water and 100 ml of toluene were added. The bottle was then 
tightly sealed with a lid containing a four-layer cellophane liner, and 
vigorously shaken on a variable speed, reciprocating shaker (Eberback 
Corp. Model 6000) set at approximately 150 excursions per minute for 90 
minutes. After shaking, the bottle contents were allowed to settle, and a 
10 ml aliquot of toluene was transferred to pipette into a glass vial and 
sealed with a polyseal cap. The toluene extract was analyzed for 
herbicidal content by gas chromatography. The chromatogram data was then 
converted to equivalent soil concentrations in parts per million (ppm) by 
weight of the herbicide. 
The results are shown in the table below, where a variety of compounds were 
tested in two separately treated batchs of soil. A control run with the 
herbicide alone and without an extender was conducted for each soil batch, 
to show how the drop in herbicide concentration was affected by the 
extender compound. In each case, the quantity of herbicide remaining in 
the soil after four days was dramatically increased when the extender 
compound was added. Many of the tests for which the results are collated 
below in Table I were run at different times. However, the control without 
extender and the parallel test with the extender were always run at the 
same time, and it is the relative differences between the EPTC residues 
with and without the extender that indicate the extender's effectiveness 
in prolonging the soil life of the thiocarbamate. 
TABLE I 
______________________________________ 
4-DAY SOIL PERSISTENCE DATA 
Herbicide: 
S--Ethyl N,N--di-propylthiocarbamate (EPTC) 
at 6 lb/A (6 ppm in soil) 
Extender: 
As shown at 4 lb/A (4 ppm in soil) 
EPTC Residue 
Extender After 4 days (ppm) 
Compound With Without 
No. Extender 
Extender 
______________________________________ 
1 0.83 0.25 
2 2.18 0.03 
3 3.53 0.03 
4 2.34 0.00 
5 3.62 0.03 
6 2.10 0.05 
6 2.54 0.05 
7 0.86 0.03 
7 1.09 0.00 
8 3.10 0.05 
9 2.16 0.03 
9 2.91 0.00 
______________________________________ 
METHODS OF APPLICATION 
The herbicidal compositions of the present invention are useful in 
controlling the growth of undesirable vegetation by preemergence or 
post-emergence application to the locus where control is desired, 
including pre-plant and post-plant soil incorporation as well as surface 
application. The compositions are generally embodied in formulations 
suitable for convenient application, containing additional ingredients, 
diluents or carriers to aid in their dispersal. Examples of such 
ingredients or carriers are water, organic solvents, dusts, granules, 
surface active agents, water-oil emulsions, wetting agents, dispersing 
agents, and emulsifying agents. The formulated compositions generally take 
the form of dusts, emulsifiable concentrates, granules, or microcapsules. 
A. DUSTS 
Dusts are dense powder compositions which combine the active compounds with 
a dense, free-flowing soild carrier. They are intended for application in 
dry form and are designed to settle rapidly to avoid being windborne to 
areas where their presence is not desired. 
The carrier may be of mineral or vegetable origin, and is preferably an 
organic or inorganic powder of high bulk density, low surface area, and 
low liquid absorptivity. Suitable carriers include micaceous talcs, 
pyrophyllite, dense kaolin clays, tobacco dust, and ground calcium 
phosphate rock. 
The performance of a dust is sometimes aided by the inclusion of a liquid 
or solid wetting agent, of ionic, anionic, or nonionic character. 
Preferred wetting agents include alkylbenzene and alkylnaphthalene 
sulfonates, sulfated fatty alcohols, amines or acid amides, long chain 
acid esters of sodium isothionate, esters of sodium sulfosuccinate, 
sulfated or sulfonated fatty acid esters, petroleum sulfonates, sulfonated 
vegetable oils, and ditertiary acetylenic glycols. Dispersants are also 
useful in the some dust compositions. Typical dispersants include methyl 
cellulose, polyvinyl alcohol, lignin sulfonates, polymeric 
alkylnaphthalene sulfonates, sodium naphthalene sulfonate, polymethylene 
bisnaphthalenesulfonate, and sodium-N-methyl-N-(long chain acid) taurates. 
In addition, inert absorptive grinding aids are frequently included in dust 
compositions to aid in the manufacturing of the dust. Suitable grinding 
aids include attapulgite clay, diatomaceous silica, synthetic fine silica 
and synthetic calcium and magnesium silicates. 
In typical dust compositions, carriers are usually present in 
concentrations of from about 30 to 90 weight percent of the total 
composition. The grinding aid usually constitutes about 5 to 50 weight 
percent, and the wetting agent up to about 1.0 weight percent. 
Dispersants, when present, constitute up to about 0.5 weight percent, and 
minor amounts of anticaking and antistatic agents may also be present. The 
particle size of the entire composition is usually about 30 to 50 microns. 
B. EMULSIFIABLE CONCENTRATES 
Emulsifiable concentrates are solutions in which the active materials and 
an emulsifying agent are dissolved in a nonwatermiscible solvent. Prior to 
use, the concentrate is diluted with water to form a suspended emulsion of 
solvent droplets. 
Typical solvents for use in emulsifiable concentrates include weed oils, 
chlorinated hydrocarbons, and nonwater-miscible ethers, esters, and 
ketones. 
Typical emulsifying agents are anionic or nonionic surfactants, or mixtures 
of the two. Examples include long-chain mercaptan polyethoxy alcohols, 
alkylaryl polyethoxy alcohols, sorbitan fatty acid esters, polyoxyethylene 
ethers with sorbitan fatty acid esters, polyoxyethylene glycol esters with 
fatty or rosin acids, fatty alkylol amide condensates, calcium and amine 
salts of fatty alcohol sulfates, oil soluble petroleum sulfonates, or 
preferably mixtures of these emulsifying agents. Such emulsifying agents 
usually comprise about 1 to 10 weight percent of the total composition. 
Typical emulsifiable concentrates contain about 15 to 50 weight percent 
active material, about 40 to 82 weight percent solvent, and about 1 to 10 
weight percent emulsifier. Other additives such as spreading agents and 
stickers can also be included. 
C. GRANULES 
Granules are physically stable, particulate compositions in which the 
active ingredients adhere to or are distributed throughout a basic matrix 
of a coherent, inert carrier with macroscopic dimensions. A typical 
particle is about 1 to 2 millimeters in diameter. Surfactants are often 
present to aid in the leaching of the active ingredient from the granule 
to the surrounding medium. 
The carrier is preferably of mineral origin, and generally falls within one 
of two types. The first are porous, absorptive, preformed granules, such 
as attapulgite or heat expanded vermiculite. A solution of the active 
agent is sprayed on the granule at concentrations of up to 25 weight 
percent of the total weight. The second are powdered materials to which 
the active ingredients are added prior to being formed into granules. 
These materials include kaolin clays, hydrated attapulgite, or bentonite 
clays in the form of sodium, calcium, or magnesium bentonites. 
Water-soluble salts may also be present to help the granules disintegrate 
in water. These ingredients are blended with the active components, then 
granulated or pelleted, followed by drying. In the resulting composition, 
the active component is distributed uniformly throughout the mass. 
Granules can be made with as much as 25 to 30 weight percent active 
component, but more frequently a concentration of about 10 weight percent 
is desired for optimum distribution. Granule compositions are most useful 
in a size range of 15-30 mesh. 
The surfactant is generally a common wetting agent of anionic or nonionic 
character. The most suitable wetting agents depend upon the type of 
granule used. When preformed granules are sprayed with active material in 
liquid form, the most suitable wetting agents are nonionic, liquid wetters 
miscible with the solvent. These are compounds generally known as 
emulsifiers, and comprise alkylaryl polyether alcohols, alkyl polyether 
alcohols, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol 
esters with fatty or rosin acids, fatty alkylol amide condensates, oil 
solution petroleum or vegetable oil sulfonates, or mixtures of these. Such 
agents usually comprise up to about 5 weight percent of the total 
composition. 
When the active ingredient is first mixed with a powdered carrier and 
subsequently granulated, liquid nonionic wetters can still be used, but it 
is usually preferable to incorporate at the mixing stage a solid, powdered 
anionic wetting agent comprising up to about 2.0 weight percent of the 
total composition. 
Typical granules comprise about 5 to 30 percent by weight active material, 
about 0 to 5 weight percent wetting agent, and about 65 to 95 weight 
percent carrier. 
D. MICROCAPSULES 
Microcapsules are fully enclosed droplets or granules in which the active 
materials are enclosed in an inert porous membrane which allows the 
enclosed materials to escape to the surrounding medium at controlled 
rates. 
Encapsulated droplets are typically about 1 to 50 microns in diameter. The 
enclosed liquid typically constitutes about 50 to 95% of the weight of the 
capsule, and may contain a small amount of solvent in addition to the 
active materials. 
Encapsulated granules are characterized by porous membranes sealing the 
openings of the granule carrier pores, trapping the liquid containing the 
active components inside for controlled release. A typical granule size 
ranges from 1 millimeter to 1 centimeter in diameter. Granules formed by 
extrusion, agglomeration, or prilling are useful in the present invention 
as well as materials in their naturally occurring form. Examples of such 
carriers are vermiculite, sintered clay granules, kaolin, attapulgite 
clay, sawdust, and granular carbon. 
Useful encapsulating materials include natural and synthetic rubbers, 
cellulosic materials, styrene-butadiene copolymers, polyacrylonitriles, 
polyacrylates, polyesters, polyamides, polyurethanes, and starch 
xanthates. 
E. IN GENERAL 
Each of the above formulations can be prepared as a package containing both 
the herbicide and the extender together with the other ingredients of the 
formulation (diluents, emulsifiers, surfactants, etc.), or as a tank mix 
in which the components are formulated separately and combined at the 
grower site. The two formulations in the tank mix can be of either the 
same type or two different types--e.g., the herbicide in microcapsule form 
and the extender as an emulsifiable concentrate. As a further alternative, 
the herbicide and extender can be applied sequentially. This is less 
preferred, however, since simultaneous application generally produces 
better results. 
In general, any conventional method of application can be used. The locus 
of application can be soil, seeds, seedlings, or the actual plants, as 
well as flooded fields. Soil application is preferred. Dusts and liquid 
compositions can be applied by the use of powder dusters, boom and hand 
sprayers, and spray dusters. The compositions can also be applied from 
airplanes as dusts and sprays becuase they are effective in very low 
dosages. In order to modify or control the growth of germinating seeds or 
emerging seedlings, as a typical example, the dust and liquid compositions 
are applied to the soil according to conventional methods and are 
distributed to a depth of at least one-half inch below the soil surface. 
The compositions can either be mixed with the soil particles by discing, 
dragging, or mixing operations, or sprayed or sprinkled over the surface 
of the soil. The compositions can also be added to irrigation water so 
that they will accompany the water as it penetrates the soil. 
The amount of active ingredient required for herbicidal effectiveness 
depends upon the nature of the seeds or plants to be controlled and the 
prevailing conditions. Usually, herbicidal effects are obtained with an 
application rate of about 0.01 to about 50 pounds per acre, preferably 
about 0.1 to about 25. It will be readily apparent to one skilled in the 
art that compositions exhibiting lower herbicidal activity will require a 
higher dosage than more active compounds for the same degree of control.