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Патент USA US3080290

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Patented Mar. 5, 1963
?ve dosages in the form of water solutions or acetone
water emulsions after the soil was planted. Readings on
seedling rot damping off ?of sugar beet seedlings were
Marvin Legator, William A. Kreutzer, and Samuel B.
Soloway, Modesto, Calih, assignors to Shell Oil Com
pany, New York, N.Y., a corporation of Delaware
made at ?ve- and ten-day intervals.
Nabam, TMTD and Captan controlled Pythium pre
No Drawing. Filed Feb. 10, 1960, Ser. No. 7,780
6 Clmms- (CL 167-32)
emergence at the highest levels only. The trimethyl phos
phorothioate was clearly superior to all other fungicides
This invention relates to the employment as a soil
111 the control of Pyihillm ulfimlmt-
fungicide of 0,0,0 - trimethyl phosphorothioate,
In order to clearly estabhsh the supenor flmslcidal
(CH3O)3PS, and to novel fungicidal compositions con~ 10 Proper-i168 0f trlmethyl.phosphorothiolate, a test was
taining this compound. This application is a continua.
made under ?eld conditions. ?Parallel tests were simul
tion-in-part of application No. 719,511, ?led March 6,
tane�� made, using the three addlti?nal Chemicals
'1958, now abandoned. It has been found that 0,0,0-
noted 1n ?the table below. These three chemicals were
trimethyl phosphorothioate manifests a highly selective
selwted 5111c? they Fire structurally _$i1_ni1a}' l0 lil'imellhyl
fungitoxic action toward soil pathogens of the Pythium 15 Phosphorothloate eXcept for the ellmmatlon and inter
type while not a?ecting plants,
change of sulfur and oxygen atoms in the various possible
O,(),O-trimethy1 phosphorothioate may be made by the
addition of sulfur to .trimethyl phosphite or by the re-
positions. The exhibited_superiority over these closely
related Chemicals along Wlth the previflllsly di_SC_11SSed 811
action of thiophosphoryl chloride with sodium methox-
?Penonty OVeI' hmjlologs and comfffel'cml funglfildes aptly
ide. Thus in one preparation of 0,0,0-trirnethyl phos- 20 illustrate the unlque and Sul'PnSmg PYOPGIUCS 0f tn
phorothioate, 32 grams of sulfur was added during the
Course of 20-30 minutes to 137 grams of trime?lyl P1105.
In this test the chem1cals were apphed as coarse aqueous
phite, maintaining a temperature of 55-60? by means of
SBI?aYS ?011 idle surface of S011 Planted Wlth Sugar beet Seed
an ice bath. The yellow solution was stirred at 60�, for
�131 Yeadlngs were made 18 and 25 ?days after the plant'
15 minutes after the ?nal addition of sulfur, ?ltered and 25 mg and treatment date- Results were as follows:
distilled to yield 98.0 grams of 0,0,0-trimethyl phos
phorothioate boiling at 66-9? at 10 mm.; nD25 1.4572.
The outstanding fungicidal activity ?of 0,0,0-trimethyl
phosphorothioate is quite surprising in view of the fact
Average Average
Cheri?licall Prelrgentl Pelrpentl
233g?; stg'rlffil S313;
that structurally similar compounds such as 0,0,O-tr1- 30
ethyl phosphorothioate and O_,0,0-tributyl phosphoroUntreated control ____________________________ __
thioate have been found relatively ineffective.
Tnmethyltetrathiophosnhate ------ -.
This altogether unexpected superiority of 0,0,0-trimethyl phosphorothioate as a soil fungicide is illustrated
by the following experiment in which the triethyl and 35 Tnmethylphosphate """"""""" "
pound. homologs
The tests were
sugar beet
with attack
the trimethyl
by Pythium.
Trimethyl phosphorotrithioite ........ _.
40 Trimethyl phosphorothioate __________ ._
45. 0
23. 7
100. 0
100. 0
Minimum Dose in MilJigrams Giving?
0,0,8,-trimgthylrpho%籬orgthiopte --------- --
g?joftt�giЁЁЁb;В,?fj;j _______ __
0. 1
1 Based on estimation of a perfect seedling stand.
2-8 45
Analysis of the data indicates that trimethyl phos
has a control level less than ?0.1 gram/foot
while trimethyl tetrathiophosphate was not effective at any
Not ?only is 0,0,O4rimethy} phosphorothioate vastly
dosage in this ?eld test. Trimethyl phosphorotrithi'oite
superior to its homologs ?as a soil fungicide against 50 gave only poor control at the dosage of least phytotoxrcity
Pythium but it also appears superior to various com(od?mm) ?and exhlblted P鞍rc皀tm1aPd was Phytotoxlc
mercial fungicides tested in accordance with the followmg procedure_
Screened soil was steamed in order to sterilize it and
at hlghef dosages ((12413 gram). Trimethyl phosphate
gave poor control at any dosage, the drop in stand at
the 04-08. gram levels mdlcatlpg phytotoX1c1.tY'
derb r tel infe ted Wim cultures ?of P thium
0,0,0-trrmethyl phosphorothio-ate shows highly selec~
in was ? s 1 61a y
s t . 25 200?
? tesz tubes 55 tive action against Pythium as evidenced by the follow
u nmimi'
contammg 7
26ml) es W61; pill Inch X. 31 mm?
grams 0 S01 '
mm 8 were ?a
dd (1 at
ing test. Pythium is a genus of fungi (family Pythiaceae)
which consists of facultative parasites and is frequently
important as a root parasite. A culture of Pythium
emergence emergence
Tetramethyl thiura disul?de (TMTD) ______ _Disodium
ultimum was isolated and the ?test chemical run against
Pythium Oontrolof- 60 this organism as well as against other soil pathogens
under in vitro conditions. The following results were
(Nabam) ______ _-_. ___________________ .__-_:-..
'l??ggloglrgethylthwtetra - hrdrophthahmlde
Trimethyl phosphorothioate ________________ _-
3 0
? Dosage test range was 3.0, 1.5, 1.0, 0.5 and 0.25 milligrams.
>3 0
Pythmm ultimum _______________________ __
it? Equimmml'
(15-1-0 70 ZZ$aO?ZfiTKTZII
____ __
Because phytotoxicity is a critical factor in evaluating
phorothioate which shows a marked speci?city for
Pythium may be employed with ?the known soil fumigant,
PCNB, pentachloronitrobenzene, which shows a marked
speci?city for Rhizoctonia. Wetting agents, and if neces
sary or desirable, stickers such as the heavy hydrocarbon
a soil fungicide, extensive phytotoxicity tests were con
ducted on sugar beet seeds. Tolerance was found to be
as high as 1-2 grams/square foot of soil. Tomato and
beet .seedlings show no apparent injury at ?0.25 gram/
square foot of soil? Pea seedlings appear to ?tolerate
dosages as high as ?0.75 gram/square foot of soil with
out undue injury. These tests also indicate that no
oils @with a minimum viscosity of 10� Engler at 50� C.
can be present. The wetting agent must be non-reactive
with the phosphorothioate. If the phosphorothioate is
phytotoxic residue is left in soils fol-lowing excessively
employed in the form of emulsion or suspension, for ex
heavy doses of 0,0,0-trimethyl phosphorothioate.
10 ample, in water, solvents such as oils, emulsi?ers, emul
The following test shows the high order of activity of
sion stabilizers, and the like may be added.
The phosphorothioate of the present invention may be
this chemical as well as a 10~20 fold range of control
without causing phytotoxicity.
applied :by spraying. Spraying of plants may be per
formed with aqueous emulsions, solutions or suspensions.
Phytotoxicity 15 The spray liquid is generally applied at a rate of from
(Sugar Beet
Concentration of O, O, O-trimethyl
phosphorothioate in Grams/Tube e
of Soil
about 7.5 to 150 gallons per acre. If spraying is e?ected
with smaller quantities of liquid as in low volume spray
.005 _________________________________ __
Complete. ____
0005; _ . . _
ing, high concentrations of the phosphorothioate should
.001 ______________________________________ _______ __
_ _ _ "do
' a Each test tube contains approximately 70 grams of soil.
These tests indicate that 0,0,0~trimethy1 phosphoro
thioate is highly selective against Pythium and compara~
tively non-toxic to plants.
be employed. If desired, a minor amount of the order
20 of about v0.011 to about 0.05% by weight, of a wetting
agent may be added to aid in forming a suspension. Par
ticularly suitable wetting agents are the sodium salts of
a mixture of secondary heptadecyl sulfates, sold commer
cially under the name of ?Teepol? and polyethylene glycol
25 ethers of alkyl phenols sold under the trade name of
?Triton X~11O?0? and ?Triton X-al55.?
Seed treatment with 0,0,0-trimethyl phosphorothioate
controls Pythium pre-emergence rot.
Preferable con
centrate compositions comprising the phosphorothioate
A talc dust con
of the present invention and a suitable wetting agent are
taining 10% w. of this compound may be used to control
prepared, and the concentrate is then dispersed in water
Pythium even :when the dust is merely sprinkled on the
surface of wet planted soil at the rate of 0.24- gram/ 30 prior to use.
A further form in which the fungicidal compound of
square foot. The material is quite effective either as an
the present invention may be applied consists of 'solu
aqueous surface drench at the time of planting or as a
tions of the active ingredient in suitable inert liquid or
dry soil mix pre-planting treatment. This compound has
also been found to stop or retard attack by established 35 semi-solid diluents, in which the phosphorothioate is
present in molecularly dispersed form. The form in which
Pythium when added to the surface of the soil following
the phosphorothioate is employed depends on the subject
seed germination.
and purpose of the application.
In order to establish the value of 0,0,0-trimethyl phos
Suitable inert solvents for ?the manufacture of liquid
phorothioate as a therapeutant, that is, as a cure for
preparations should not ?be readily ?ammable, as odorless
plant disease \which has already become established, the
?following test was conducted.
Beet seeds were treated
40 as possible and without any toxic elfect on humans and
animals when properly used. lNeither should they have a
with tetramethyl thiuram disul?de (Thiram) for the pur
pose of controlling pre-emergence attack.
corrosive effect on the components of the preparations or
Both treated
the material of the storage vessel. Examples of suitable
solvents are high-boiling oils, e.g., oils of vegetable origin
such as castor oil, etc., and lower boiling solvents with
and non-treated seeds were planted at one-half inch levels
in standard 25 x 200 mm. tubes. Aqueous drenches at
varying doses of 0,0,0-tn'methyl phosphorothioate were
a ?ash point of at least 30� C., such as carbon tetra
added either at the time of emergence or after emergence
chloride, ethylene dichloride, acetylene tetrachloride, hy
drogenated naphthalene, alkylated naphthalene, sorbcnt
at the ?rst appearance of post emergence attack. Con
trol was brought about in all cases.
Secondary Treatment
Seeds Treated with
naphtha, etc. Mixtures of solvents may also be used.
Non-aromatic petroleum oils and xylene are commonly
Seeds not treated
0,0,0籺rirnethyl phos
phorothioate aqueous
Normal stands Post
emergence 1* attack
drench at time of
emergence (4 days).
0,0,0-trimcthyl phos
phorothioate aqueous
controlled by 0.3-1.0
emergence rot.
Normal stands Post
drench at ?rst sign of
post emergence attack
(8 days).
This compound may also be employed in the form of
aerosols. 'When so used the phosphorothioate is dissolved,
or ?dispersed in 1a solvent boiling below room tempera
N0 stand; complete
55 ture ?at atmospheric pressure.
emergence e attack
controlled by 0.3
N o secondary treatment- Normal stands; partial No stand; complete
pre-emcrgence rot. 60
damping o?".
0,0,0,-trimethyl phosphorothioate may also be ?applied
in [the form of dusts utilizing as the inert vehicle such
materials as tricalcium phosphate, precipitated chalk, ben
tonite, kaolin, kieselguhr, etc.
It has been found that activated carbon is a most satis
factory inert vehicle for the formulation of such fungicidal
dusts. -Any of the various types of activated carbon may
be used. ?For example, activated carbon obtained from
In view of this test 0,0,0-trimethyl phosphorothioate
appears to have de?nite therapeutic action. There was 65 the carbonization ?of plant raw materials, from charcoal
?formed "by steeping the raw material in zinc chloride, or
no sign of phytotoxicity at control levels. Thus this
by mixing the raw material with carbonates such as
compound may be applied to the soil to prevent the estab
calcium carbonate are all suitable ?as the inert vehicle.
lishment of the fungus, applied during the post-emergence
?It is prefer-red to use Columbia activated carbon for ?this
period of the plant to destroy the established pathogens,
and applied to the seed before planting.v
A trimethyl phosphorothioate-activated carbon dust is
O,?O,~O-trimethyl phosphorothioate may be employed
attended by ?a loss of the trimethyl phosphorothioate with
alone or in combination with other fungicidal, viricidal,
the passage of time. This instability has been an economic
9- Pythium ultimum attack.
insecticidal, or acaricidalvmaterials, the action of which
may be either internal or external, with plant nutritives,
plant hormones and the like.
drawback to this formulation as well as a problem in stor
age when the dust was not to be promptly used after
0,0,0-trimethy1 phos 75 formulation.
By means of infrared ?analysis of CS2 extracts of the
trimethyl phosphorothioate-activated carbon dust at vari
ous proportions over a period of 20 days, it has now been
discovered that when the trimethyl phosphorothioate is
present in the dust in concentrations of up to approximate
ly 40% by weight, the loss of trimethyl phosphorothioate
is very much reduced over that at higher concentrations.
soil comprising the rhizosphere of the plant an effective
dosage of 0,0,0-trimethyl phosphorothioate.
2. The method for protecting viable seed and the plant
sprouting therefrom from attack by Pythium fungi which
comprises applying an effective dosage of 0,0,0-trimethyl
phosphoro-thioate to seed prior to the time the seed is
3. The method according to claim 2 wherein the
Therefore, the fungicidal dust comprising activated char
0,0,0-trimethyl phosphorothioate is applied in the form
coal and up to approximately 4(}% by weight of trimethyl
phosphorothioate is preferred when a dust formulation is 10 ?of 4.a dust.
The method for overcoming attack by Pythium fungi
desired. ?If this preferred embodiment is utilized, the
and preventing further attack by said fungi comprising
percent loss in storage will be relatively low with a re
introducing into the soil comprising the rhizosphere of
sulting monetary savings.
the plant undergoing attack by Pythium fungi an effec
The method of application may vary considerably with
dosage of 0,0,0-trimethy-l phosphorothioate.
out departing from the scope of the invention. Thus the 15 tive5. The
method for protecting viable seed and the plant
phosphorothioate may ?be applied to the entire area of "a
sprouting therefrom from attack by Pythium fungi which
?eld. This procedure is called solid, or broadcast, applica
comprises introducing into the soil in which the seed is
tion. The chemical may also be applied in rows or hills
to ?be planted, and within a short time before the seed is
Where the plants are to grow. It is preferable to inject
the soil fungicide at uniform depth. However, it is also 20 planted, an effective dosage of 0,0,0-trimethyl phos
possible to apply the chemical as a surface treatment
6. A fungicidal dust comprising activated charcoal and
when mixed with water or with a powder carrier. When
up to approximately 40% by weight of trimethyl phos
mixed with a higher boiling point diluent the chemical
may be injected into the soil. The chemical may be
pre-mixed with the seeds or applied as part of the seeding 25
References Cited in the ?le of this patent
operation if desired. Other methods of application will
also be apparent to those versed in the art, it being
Scott ________________ __ Nov. 18, 1958
understood that the methods of application are not limited
to those speci?cally enumerated.
We claim as our invention:
in Pest Control Research, pp. 227
1. The method for protecting a living plant from attack
228 and 232, vol. '1, June 1951.
by Pythium fungi which comprises introducing into the
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