Note: Descriptions are shown in the official language in which they were submitted.
3~
DESCRIPTION
"NEW PESTICIDAL COMPOUND"
This invention relates to S,S-di(tert-butyl~
ethylphosphonodithioate, pesticidal compositions which
; comprise it as active ingredient and to its use as an
insecticide and nematocide.
The compound of the invention has the formula
3CH2 P(~)[~SC(CH3)3]2 (formula I) and
exhibits a wide range of insecticidal and nematocidal
activity and possesses excellent stability and long
residual activity particularly in soil.
The compound may be used, in particular, in
agriculture, against adults, larvae and eggs of
Lepidoptera (butterflies ~ moths), e.g. Heliothis spp.
such as Heliothis virescens (tobacco budworm),
Heliothis armi~era and Heliothis zea, Spodoptera spp.
such as S. exem~ta, S. littoralis (Egyptian cotton
; worm), S. eridania (southern armyworm), Mamestra
configurata (bertha armyworm); Earias spp. e.g.
E. insulana (Egyptian bollworm), Pectinophora spp.
e.g Pectinophora ~ossypiella (pink bollworm),
Ostrinia spp. such as 0. nubilalis (European
cornborer), Trichoplusia ni (cabbage looper), Pieris
~ 733 ~
spp. (cabbage worms), Laphy~ma spp. (armyworms),
Agrotis and Amathes spp. (cutworms), Wiseana spp
(porina moth), Chilo spp. (rice stem borer), Tryporyza
spp. and Diatraea spp. (sugar cane borers and rice
borers), Spar~anothis pilleriana (grape berry moth),
Cydia pomonella (codling moth), Archips spp. (fruit
tree tortrix moths), Plutella xylostella (diamond back
moth); against adults and larvae of Coleoptera
(beetles) e.g. Hypothenemus hampei (coffee berry
borer), Hylesinus spp. (bark beetles), Anthonomus
~randis (cotton boll weevil), Acalymma spp. (cucumber
beetles), Lema spp., Psylliodes spp., Leptinotarsa
decemlineata (Colorado potato beetle), Diabrotica spp.
(corn rootworms), ~onocephalum spp. (false wire
worms), Agriotes spp. (wireworms), Dermolepida,
Lepidiota and Heteronychus spp. (white grubs), Phaedon
cochleariae (mustard beetle), Liss_rhoptrus
oryzophilus (rice water weevil), Meli~ethes spp.
(pollen beetles), eutorhynchus spp., Rhynchophorus
and Cosmopolites spp. (root weevils); Sitona spp.
(pea ahd bean weevils); against Hemiptera e.g. Psylla
spp., Bemisia spp., Aphis spp., Myzus spp., Me~oura
viciae, Phylloxera spp., Adel~es spp., Phorodon humuli
(hop damson aphid), Aeneolamia spp., Nephotettix spp.
(rice leaf hoppers), Empoasca spp., Nilapa_vata spp.,
Perkinsiella spp., Pyrilla spp., Aonidiella spp. (red
~7~ i5
-- 3 --
scales), Coccus spp., Pseudococcus spp., ~elopeltis
spp. (mosquito bugs), ~us spp., Dysdercus spp.,
Oxycarenus spp., Nezara spp., Hymenoptera e.g. Athalia
spp. and Cephus spp. (saw flies), Atta spp.(12af
cutting ants); Diptera e.g. Hylemyia spp. (root
flies), Atherigona spp~ and Chlorops spp. (shoot
flies), Phytomyza spp. (leaf miners), Ceratitis spp~
(fruit flies); Thysanoptera such as Thrips tabaci;
Orthoptera such as Locusta and Schistocerca spp.
(locusts), crickets e.g. Gryllus spp. and Acheta spp
and Gryllotalpidae (mole crickets); Collembola e.g.
Sminthurus spp. and Onychiurus spp. ~springtails),
Isoptera e.g. Odontotermes spp. (termites), Dermaptera
_.
e.g. Forficula spp. (earwigs) and also other
arthropods of agriculture signific~ance such as Acari
(mites) e.g. Tetranychus spp., Panonychus spp. and
Bryobia spp. (spider mites), Eriophyes spp. (gall-
mites), Po~yphagotarsonemus spp.; Blaniulus spp.
(millipedes), Scutigerella spp. (symphilids), Oniscus
spp. (woodlice) and Triops spp. (crustacea) and also
plant-attacking nematodes infesting both roots and
shoots such as cyst nematodes (Heterodera spp.,
Globodera spp.), root-knot nematodes (Meloidogyne
spp.), lesion nematodes (Pratylenchus spp.), dagger
nematodes (Xiphinema spp.) and stem and bulb eelworms
(Ditylenchus spp.).
~%~
_ b, --
Since the activity of the compound against
corn rootworm (Diabrotica sp.) is good and residual
activity in soil is long, the compound of this
invention is of special interest for controlling corn
rootworm. The duration of residual activity in soil of
the compound against corn rootworm is unexpectedly
superior to that of compounds of related chemical
structure, as has been demonstrated in the following
experiment described in Example 1.
EXAMPLE 1 : EXPERIMENT
The compounds tested were of the general
formula:-
- R(X)P(=Xl)(X2Rl)(X3R2) (IA)
Compound R (X) Xl X2 Rl X R
A Et - 0 S t-butyl S t-butyl
B Et - 0 S n-propyl S t-butyl
C Et - 0 S iso-propyl S t-butyl
D Et - 0 S iso-butyl S t-butyl
E Et - 0 S n-butyl S t-butyl
F Me - 0 S n-propyl S t-butyl
G Et - S S t-butyl 0 iso-propyl
H Et - S S t-butyl 0 t-butyl
I Et 0 0 S t-butyl S t-butyl
- J Et 0 0 S t-butyl S sec-butyl
~7
-- 5 --
COMPOUND
A is the Compound of the present invention
B is Compound No. 2 of United States Patent No 4,472,390
C is Compound No. 7 of United States Patent No. 4,472,390
D is Compound No. 9 of United States Patent No. 4,472,390
~ is Compound No. 10 of United States Patent No. 4,472,390
F is Compound No. 12 of United States Patent No. 4,472,390
G is Example 8 of United States Patent No. 4,268,508
H is a congener of Compound A within United States Patent
No. 4,268,508
I is Compound No. 11 of PCT Patent Application No.
WO 83/008870
J is Compound No. 10 of PCT Patent Application No.
WO 83/008870
Test for residual activity and persistence a~ainst
Corn rootworm (Diabrotica sp.)
Test Method
The soil used was a clay-loam having a water
content of approximately 23% of the oven-dry weight
(determined by drying a sample for 24 hours at 110C).
All rates of the treatments with the test compound were
expressed.as parts per million (ppm) of the oven-dry
weight of the soil. Before treatment with the test
compound, thè soil was passed through a 3.5mm aperture
screen.
The test compound was dissolved in dimethyl
ketone to give concentrations such that the addition
~2~ ~ 3
- 6 -
of 1 ml quantities of the solution to soil samples
equivalent to lOOg of oven-dry soil, gave
concentrations of 0.1 and 0.5ppm, and, in some cases,
0.05ppm, of test compound.
Soil samples equivalent to 500g of oven-dried
soil were placed in polyethylene bags and 5ml of
solution of the test compound in dimethyl ketone
containing the desired concentration of test compound
was added. The contents of the bags were then
thoroughly mixed. The bags were then opened for one
hour to allow dimethyl ketone vapour to disperse.
Samples o~ soil taken from the bags were
tested immediately for activity against Diabrotica
undecimpunctata (Day 0). The remaining soil was then
stored in sealed dark glass jars at 24C and further
samples were taken and tested on the 7th, 14th, 21st,
28th, 42nd 56th, 70th and ~4th day after treatment
with the test compound (Days 7, 14, 21, 28, 42, 56, 70
and 84), the soil being remixed before withdrawal of
the sample.
Activity against Diabrotica was determined by
the following procedure:-
Diabrotica were reared at 25C on maize
seedlings.
~ 733 ~ ~
Approxima~ely 20g of treated soil was placed
in a 25 x 75mm glass vial containing 2.5ml of
distilled water and a sprouted maize seedling with
good root development, Five 5-day old Diabrotica
larvae were placed upon the soil and any not burrowing
into the soil after a few minutes were replaced until
all the larvae had burrowed.into the soil. The tube
was covered with a wire mesh lid and kept at 25C for
four days. Each treatment was replicated four~fold,
up to and including Day 42, two replicates being used
~n Days 56, 70 and 84. After the four day period, the
samples were examined, the numbers of dead and living
larvae were counted and the mean percentage mortality
of larvae calculated from the four replicate
treatments in comparison with untreated controls.
A mean percentage mortality of 90 or greater
indicates a satisfactory level of control of
Diabrotica sp larvae.
-
The results obtained are shown in the
following Tables I and II.
,', '' ,.....
~o o o o o #
O U~ O ~) ~1 J,~ _ Ll-~ # _ O # _ _
r~l C~l O O 'D O O O I-~ O
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a~ ~ o o u~ u~ # o u~ # O O ~ J,~
t~ ~ ,__1 O (~ t~ C~ O O ~1 O O ~1 O
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C~,O _ _ _ _ _ _ _ _ _ _ _ _
C,D ~ ~ oo O oo O O oo ~C) C:~ O Irl ~O O
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~ _ _ _ _ _ _ _ _ _ ._ _ _
O O U~ O O O U~ U~ O O O O
I~ O O ~ O cr~ O 7 C~l O C~ 1~ 1_1
_ ~ ~ _ ~ _ ~ _ _ ~ _ _ _
O O O O U~ O O O O O O O
o o o c,~ o a~ o o ~, o ~ o .
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t~ ~ U~ Lr~
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c a- o
C ~ ~
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u~ 5 ~ P::l C~ ~ ~
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~733~
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O o~ ~ ~ c o _ _ _ o o c o
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C~ . o ~0
~1 a~ ~ 4-1 ~1 ~O ~; _ 3
C~ O O U~ l_ l + + + + + + +
,_1 ~ O ~ O O
Ei~ .~
a~ ~ _ _ _ _ _ _ _ _ _ _ ~ ~ ~
C~ 0 ~ . -C C ^ J-
c: a~ s ~: 0
v 01 o o v ~ o ~ o ~ + + ~ ~ v ~ E ~ C v
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_ _ _. _ _ _ _ _ ._ _ _ _ _~o C JJ O ~I 0
~ ¢ :q ~ ~ ~ ~ c~ :C ~ ~ CCc
E~ C~ _ - - - - I - - ~- ~ +
~ 33 ~ ~
From the above results, it will be seen that:-
(1) At a concentration of O.lppm, Compound A gave a
satisfactory level of control of Diabrotica
larvae for more than six times as long as
Compound B, Compound A having been shown to give
a satisfactory level of control up to Day 42,
whereas Compound B had ceased to give a
satisfactory level of control by Day 7. Eu~n at
- a concentration five times greater (0.5ppm),
Compound B ceased to give a satisfactory level
of control between Day 28 and Day 42.
Furthermore, Compound A gave a satisfactory
level of control up to Day 14 even at the low
concentration of O.OSppm, whereas, as mentioned
above, Compound B had ceased to give
satisfactory control by Day 7 even at a
concentration twice as great (O.lppm).
(2) At a concentration of O.lppm, Compound A gave a
satisfactory level of control of Diabrotica
larvae for more than six times as long as
Compound C, Compound A having been shown to give
a satisfactory level of control up to Day 42,
whereas Compound C had ceased to achieve a mean
- l2 -
percentage mortality of 90% by Day 7. At half
this concentration (0.05ppm), Compound A gave a
satisfactory level of control up to Day 14,
whereas Compound C did not achieve this level of
activity even on Day 0.
(3) Even at a concentration of 0.5ppm, Compound D
ceased to give a satisfactory level of control
of Diabrotica larvae by Day 28, whereas, in
contrast, Compound A gave satisfactory control
for twice as long, up to Day 42, at a
concentration five times lower (O.lppm). At a
concentration of O.lppm, Compound D failed to
give satisfactory control even on Day 0, whereas
Compound A gave satisfactory control at this
concentration up to Day 42 and even at a
concentration five times lower (0.05ppm) gave
satisfactory control up to Day 14.
(4) At a concentration of 0.5ppm, Compound E had
ceased to give a satisfactory level of control
. of Diabrotica larvae by Day 7, whereas even at a
concentration five times lower (O.lppm),
Compound A gave satisfactory control for more
than six times longer, up to Day 42. Even at a
concentration ten times lower (0.05ppm),
Compound A gave control for twice as long, up to
1 3 - ~ ~733~i
Day 14, than was achieved by Compound ~ a~
0.5ppm~ At a concentration of O.lppm, Compound
E showed little or no activity even on Day 0,
whereas at this concentration, Compound A gave a
satisfactory level of control up to Day 42 and
even at half this concentration (0.05ppm) gave a
satisfactory level of control up to Day 14.
(5) At a concentration of O.Sppm, Compound F had
ceased to give a satisfactory level of control
of Diabrotica larvae by Day 14, whereas at a
concentration five times lower (O.lppm) Compound
A gave satisfactory control for at least three
times longer, up to Day 42 and even at a
concentration ten times lower (0.05ppm),
Compound A gave satisfactory control lasting
twice as long, up to Day 14. At a concentration
of O.lppm, Compound F did not achieve a
satisfactory level of control even on Day 0,
~hereas at this concentration Compound A gave a
satisfactory level of control up to Day 42 and
even at half this concentration (0.05ppm) gave a
satisfactory level o~ control up to Day 14.
(6) Neither Compound G nor Compound H gave a
satisfactory level of control of Diabrotica
larvae even on Day 0 at concentrations of 0.5ppm
and O.lppm, whereas Compound A gave satisfactory
- 14 - ~ ~7
levels of control up to Day 42 and Day 141
repectively, at concentrations only one fifth
(O.lppm) and one tenth (0.05ppm) as great,
respectively, as the highest concentration
(0.5ppm) of Compound G and Compound H tested.
(7) At a concentration of O.lppm, Compound I failed
to give a satisfactory level of control against
Diabrotica larvae even on Day 0, whereas at this
concentration, Compound A gave satisfactory
control up to Day 42 and even at a concentration
five times lower (0;05ppm) Compound A gave
satisfactory control up to Day 14. At a
concentration of 0.5ppm, Compound I had ceased
to give a satisfactory level of control by Day
56, whereas at that concentration Compound A
gave satisfactory control up to Day 84 and even
at a concentration five times lower (O.lppm3
gave satisfactory control for a period
comparable to that obtained by Compound I at a
concentration five times greater (0.5ppm).
(8) Even at a concentration of 0.5ppm, Compound J
had ceased to give a satisfactory level of
control of Diabrotica larvae by Day 14, whereas
- Compound A, at a concentration five times lower
(O.lppm) gave satisfactory control for at least
three times longer, to Day 42 and at a
- 15 ~ 3~ ~ ~
concentration ten times lower (0.05ppm) Compound
A gave a satisfactory level of control which
lasted twice as long, up to Day 14. At a
concentration of O.lppm Compound J failed to
give satisfactory control even on Day 0, whereas
at that concentration, Compound A gave
satisfactory control up to Day 42 and even at a
concentration five times lower (0.05ppm) gave
satisfactory control up to Day 14.
t9) At a concentration of O.lppm, Compound A gave a
satisfactory level of control of Diabrotica
larvae which persisted for more than six times
as.long, i.e. at leasc up to Day 42, as the most
persistent of the comparison compounds at O.lppm
(Compound B and Compound C) 7 which at this
concentration had ceased to give a satisfactory
level of control of Diabrotica by Day 7, while
none o~the other seven comparison compounds
gave a satisfactory level of control of
Diabrotica even on Day 0.
(10) In terms of mean percentage mortality of
Diabrotica produced at Days 21, 28 and 42 at a
concentration of O.lppm, the results given in
Table I show that at Day 21, Compound A was six
times more active than Compound C and nine times
more active than Compound D and that at Day 28,
Compound A was nine and a half times more active
- 16 - ~Z733~;iS
than Compound C and nineteen times more active
than Compound D, the remaining seven comparison
compounds having ceased to show activity by
these Days, while at Day 42, Compound A produced
90% mean percentage mortality of Diabrotica,
whereas all nine comparison compounds had cea.sPd
to show activity by Day 42.
The results given in Tables I and II clearly
demonstrate the unexpected and substantial
10 ` advantage of Compound A over the nine comparison
compounds in terms both of persistence of a
satisfactory level of control of Diabrotica and
in activity against Diabrotica at given times
after application of the test compounds. This
is particularly well shown by consideration of
the results obtained at a concentration of
O.lppm of test compound, where a satisfactory
level of control of Diabrotica was obtained with
Compound A at least to Day 42, whereas one
comparison compound at this concentration
(Compound C) had ceased to give satisfactory
control at Day 14, one comparison compound
(Compound B) had ceased to give satisfactory
control at Day 7 and the remaining seven
comparison compounds failed to achieve
- 17 - ~ ~
satisfactory control on Day 0. Even at a
concentration fiv'e times as high (0.5ppm) only
two of the comparison compounds (Compound C and
Compound I) gave satisfactory control for as
long as, or slightly longer than that given by
Compound A at the five-fold lower concentration,
of O.lppm and even here Compound C and Compound
I had ceased to give satisfactory control by Day
56, while Compound A gave satisfactory control
1~ beyond Day 84 at a concentration of 0.5ppm.
The following Examples 2 to 7 further illustrate
the valuable insecticidal and nematocidal properties
of S,S-di(tert-butyl)ethylphosphonodithioate
(Compound A).
EXAMPLE 2 : The control of corn root-worm on field
maize
Compound A formulated as a 10% granule was
applied in a band at t,he time of seed drilling to the
soil of a plot of field maize infested with corn
root-worm. The maize plants were later uprooted and
their roots assessed for damage caused by corn
root-worm (Diabrotica spp.) using a conventional root
rating scale in which 6.0 represents maximum pest
attack and 1.0 the absence of visible damage. The
rates of application indicated below are those of
Compound A in kilogrammes per hectare (kg/ha). The
following results were obtained:-
- 18 ~
Rates of Root ratings
application
(kg/ha) Replicate plots mean
~ .
Compound A A B C D
0.842.1 2.2 2.1 1.8 2.05
0.562.6 2.1 2.4 1.9 2.25
50.282.8 2.8 2.9 2.3 2.70
_
untreated 5.9 5.9 4.9 3.6 5.08
The low root ratings obtained in the Compound A
treatments in comparison with those of the untreated
controls demonstrate the high effectiveness of this
compound against corn root-worm.
EXAMPLE 3 : The control of seed corn maggot on field
maize
Compound A formulated as a 20V/o granule was
applied as a band or as an in-furrow treatment to the
soil of a plot of field maize infested with seed corn
maggot at an application rate of 1.12 kg/ha of Compound
A, both treatments being made at the time of seed
drilling. The efficacy of the treatment against the
seed corn maggot (Hylemyia pl~tura) was later
determined by counting the fly pupae along sample
lengths of a row. The numbers found in the treated
plots were recorded as a percentage of those found in
the untreated controls. The following results were
obtained:-
- 19 ~
pupae found as a
Compound A the control
as a band treatment 15
as an in-furrow treatment30
The reduction of pupae by 85% and 70%
respectively demonstrates the high activity of Compound
A against seed corn maggot.
E~AMPLE 4 : The control of mole crickets in turf
Compound A formulated as a 20% granule was
applied to turf infested with mole crickets (species of
Gryllotalpidae) at application rates equivalent to 5.56
and 11.2 kg/ha of Compound A. The mounds of soil
produced by the insects were recorded before and after
treatment. The following results were obtained:-
Compound A Untreated
number of mounds
pre treatment 13.8 7.3
post treatment 2.8 8.3
pre treatment 10.3 15.0
p~st treatment 1.5 17.0
The large reduction in numbers of mounds from the
pre to the post treatment counts demonstrates the
usefulness of Compound A in the control of
mole-crickets.
- 20 ~ 73 3~ ~
EXAMPLE 5 . The control of_pea and bean weevil larvae
on field beans
.
Compound A formulated as a 10% granule was
applied in ~wo experiments to the soil around emerging
spring sown field beans in a plot infested with pea and
bean weevil at rates equivalent to 1 kg/ha and 2 kg/ha
of Compound A. Plots were replicated four times in
Experiment 1 and three times in Experiment 2.
Approximately seven weeks later plants were uprooted
and the numbers of weevil larvae on the roots
counted. The results were expressed as the mean
percentage reduction in larval numbers in comparison
with untreated control plants. The following results
were obtained
Compound A % reduction of larval numbers
(kg/ha) Experiment 1 Experiment 2
2 90.2 92
1 53.3 93.75
. The large reduction in larval populations
obtained with Compound A, particularly at the 2 kg/ha
application rate in Experiment 1 and Experiment 2 and
at the 1 kg/ha application rate in Experiment 2,
demonstrates the effectiveness of this compound against
pea and bean weevil larvae.
- 21 -
EXAMPLE 6 : Test to measure effectiveness a~ainst_cane
white grub
Compound A was dissolved in acetone and this
solution was used to treat quantities of soil to give a
range of known concentrations of the compound in the
soil. After evaporating the solvent, the treated soil
was placed in glass jars (about 110 g of soil per
jar). Twenty jars were prepared for each
concentration. Each jar then received one third-
instar larvae of the cane white grub Lepidiotafrenchi. Twenty-eight days later the mortal'ities of
- the larvae were assessed. The following results were
obtained:-
Application % mortalities
rate of Compound A corrected for those in
15 in mg/kg of soil the controls
0.5 47
1.0 89
2.0 95
4.0 ` 100
8.0 100
The results obtalned demonstrate the high
insecticidal activity o~ Compound A against cane white
grubs.
~ - 22 -
EXAMPLE 7 : Tests for nematocidal acti~tity
(a) Ditylenchus dipsaci (stem and bulb eelworm)
The nematodes were cultured on lucerne plants
(cv. du Puits) in a glasshouse. Two or three months
after initial infection, plants were harvested , washed
and eggs and larvae of the nematodes recovered from
them by steeping lacerated stems and leaves in water.
After sieving, an inoculum suspension containing about
150 larvae per millilitre was prepared in distilled
water.
Equal parts of uncontaminated soil, sieved to a
particle size of-l to 2 mm, and of river sand were
mixed. To batches of this soil were added Compound A
under test, previously dispersed in distilled water -
with the aid of Tween 80, to give the required range of
dilutions of chemical in soil.
Plastic plant pots of 200 ml capaci~y were part
filled with coarse untreated sand on which were sown
100 lucerne seeds per pot. The pots were then filled
with chemically treated soil, except in the case of
untreated controls where untreated prepared soil was
used. Each pot was watered from above with 5 ml of
the nematode suspension such that each pot received
about 750 larvae. Pots were held at a moisture
content optimum for seed germination and plant growth.
~ ~ 3 3
- 23 -
Twelve to fourteen days later, ~he lucerne
seedlings were harvested and inspected for nematode
attack. The efficiency of each treatment was
determined as the percentage reduction in attack in
comparison with the untreated controls. The following
results were obtained in two experiments:-
AOfplcoapouondrAte compared with controls
tkg/ha) Experiment 1 Experiment 2
_
100 100
100 100
100
1 ~ 60
.
("-" means "not tested at this application rate in this
experiment")
(b) Meloidogyne incognita (Root-knot nematode)
The culture was maintained on tomato plants in a
glasshouse. A standard root-knot nematode inoculum
suspension of about 1500 eggs per millilitre of
distilled water was prepared from washed, macerated and
sieved roots. At least 10 to 15% of the eggs were at
the embryonic larval stage.
- 2~ -
Soil prepared for the experiments consisted of a
mixture of equal parts of river sand, peat and
uncontaminated soil prepared by hand-mixing. This was
inoculated with enough egg suspension to give about
30,000 eggs per litre of soil. Compound A was
dissolved in acetone and adsorbed onto a small quantity
of Attaclay, the acetone then being removed by
evaporation. Except for the untreated control soil,
batches of soil were then hand mixed with the treated
Attaclay to provide the required range of dilutions of
the test chemical in the final batches of soil.
Two replicate plant pots were filled from each
soil batch. These were watered and maintained in a
hu~id atmosphere for two weeks. Two small tomato
plants (cv. Marmande) were then transplanted into each
pot, these being maintained in a glasshouse for a
further four weeks.
The plants were then harvested, washed and the
root, galls counted. The efficacy of each treatment
was determined on the percentage reduction in galling
in comparison with the untreated controls. The
following results were obtained in ~wo experiments:-
- 25 -
__
. . %age reduction in attack
Appllcatlon rate compared with controls
of Compound A
(kg/ha) Experiment 1 Experiment 2
_
100 100
100 100
~5 100 100
100 90
0
- O
("-" means "not tested at this application rate in this
experiment")
The above results demonstrate the high level of
activity against Ditylenclus dipsaci and the very high
level of activity against Meloido~y~ ingcognita of
Compound A.
~1~r~r~
- 26 -
The compound of the invention can be prepared by
methods known per se. (By the term 1methods known per
_ ' as-used in the present specification is meant
methods here~ofore used or described in the cbemical
literature). Preferably, the compound of this
invention is prepared from a starting material which is
an ethyl phosphonic halide. The ethyl phosphonic
halide is reacted with 2-methylpropane-2-thiol in the
presence of a base to arrive at the compound of this
invention.
According to a feature of the invention the
compound of formula I is prepared by the process which
comprises reacting an ethyl phosphonic halide of the
general formula CH3CH2-P(=0)(-X)-Xl (general
formula II) wherein X represents a halogen atom,
preferably chlorine, and Xl represents a halogen
atom, preferably chlorine, or a tert-butylthio group
[SC(CH3)3] with, when Xl represents a halogen
atom, generally two molar equivalents or, when Xl
represents a tert-butylthio group, generally one molar
equivalent of 2-methyl-propane-2-thiol, in the presence
of a base, or with the thiol alkali metal, e.g. sodium,
salt.
The process proceeds in accordance with the
following Reaction ScheMes A and B:-
Reaction Scheme A (Xl represents a halogen atom)
- 27 -
CH3CH2-P(=O)(-X)-Xl + 2 CH3C(SH)(CH3)CH3
(IIA)
3CH2 P( )[~SC(CH3)3]2 + 2 base. HX/HX
(I)
Reaction Scheme B [X1 represents -SC(CH3)3]
CH3CH2 P(=O)(-X)-SC(CH3)3 ~ CH3C(SH~(CH3)CH3
(IIB)
3cH2-p(=o)~-sc(cH3) 3]2 + base. HX
(I)
wherein X and X1 are as hereinbefore defined. The
reaction depicted in Reaction Scheme A is preferred
for the preparation of the compound of the formula I.
The process is advantageously carried out at a
temperature of about 0C to 100C in an organic
solvent using an alkali metal salt of the thiol,
prepared from the thiol and an alkali metal, e.g.
sodium, or hydride thereof or an alkali metal
hydroxide, e.g. sodium hydroxide.
Suitable organic solvents are, for example,
benzene, toluene, cyclohexane, tetrahydrofuran,
dimethylformamide, 2-butanone and acetone (dimethyl
ketone).
Compounds of general formula II may be prepared
by methods known ~ se. For example, the compounds
of general formula IIA may be prepared by the
procedures described by Morita et al, Tetrahedron
- 28 -
Letters, 28, 2522-6 (1978), Morita et al, Chemistry
Letters (1980), 435-8, ~itish Patent No. 1,374,757 and
Pianfetti and Quin, J.Amer.Chem.Soc.j 84, 851 (1962)
and the compounds of general formula IIB may be
prepared by the procedure described in published
British Patent Application No 2087891A. 2-Methyl-
propane-2-thiol may be prepared by the procedure
described by Dobbin, J.Chem.Soc., 57, 641.
The compound of this invention is effective as
an insecticide and/or nematocide at low
concentrations. Because of the small amounts of the
compound required for effective control, it is
generally impractical to apply the compound directly
as such. Therefore, it is desirable that the compound
be applied in the form of insecticidal or nematocidal
compositions comprising S,S-di~tert-b~ltyl) ethyl-
phosphonodithioate in association with, and preferably
homogeneously dispersed in, one or more compatible
agriculturally-acceptable diluents or carriers and/or
surface-active agents (i.e~ diluents or carriers
and/or surface active agents accepted in the art as
being suitable for use in insecticidal or nematocidal
compositions and which are compatible with the active
ingredient).
Compositions for application comprising the
active compound of this invention can be liquid
33
- 29 -
dispersions or emulsions, preferably comprising from
about 0.001% to about 1% w/v (weight/volume) of the
active compound. Since the active compound is
substantially water insoluble, it is desirable to add
an inert, non-phytotoxic organic solvent to give a
concentrate, which pre~erably comprises from about 2%
to about 75% w/v of the active compound and which can
. . .
be readily dispersed in an aqueous medium to produce a
uniform dispersion of the active compound for
application. The compositions will also usually
comprise a surface-active agent. For example, an
effective liquid composition can be prepared with the
active compound, acetone or ethanol, water, and a
surface-active agent such as Tween-20 (polyoxyethylene
sorbitan monolaurate) or any of the other suitable
surface-active agents.
The compositions containing the active compound
can also be in solid, e.g. powdered or granular,
form. For example, the active compound can be mixed
with a suitable solid carrier such as kaolinite,
bentonite, talc or the like, or incorporated into
suitable granules, for example of mineral clays, e.g.
attapulgite, mont~orillonite, diatomite or sepiolite.
Preferably, the compositions in powdered form comprise
from about 0.5% to about 25% w/w (weight/weight) and
the compositions in granular form preferably comprise
from about 1% to about 25% w/w, of the active compound.
-- - 30 -
Compositions comprisin~ the active compound may
also comprise other pesticidal components, far example
insecticides, nematocides and fungicides, e.g.
thiofanox, carbofuran, aldicarb and benomyl.
For the control of insects and nematodes, the
active compound i.5 generally applied to the locus in
which insect or nematode infestation is to be
controlled at a rate of about 0.lkg to about 25kg of
active compound per hectare of locus treated. Under
ideal conditions, depending on the pest to be
controlled, ~he lower rate may offer adequate
protection. On the other hand, adverse weather
conditions, resistance of the pest and other factors
may require that the active ingredient be used in
higher proportions.
When the pest is soil-borne, the formulation
containing the active compound is distributed evenly
over the area to be treated in any convenient manner.
Application may be made, if desired, to the field or
crop-growing area generally or in close proximity to
the seed or plant to be protected from attack. The
active component can be washed into the soil by
spraying with water over the area or can be left to
the natural action of rainfall. During or after
application, the formulation can, if desired, be
distributèd mechanically in the soil, for example by
ploughing or disking. Application can be prior to
73~r~
- 31 -
planting, at planting, aEter planting but before
sprouting has taken place or after sprouting.
The following Example illustrates the
preparation of the compound of the present in~JentiOn:-
EXAMPLE 8 : Preparation of S,S-di(tert-but~l)
eth 1 hos honodithioate
Y P P _ .
Sodium hydride (3.0g, 0.125 mole) was suspended
in dry tetrahydrofuran (70ml) at 0C. 2-methylpropane-2
-thiol (14.1ml, 0.125 mole) was then added dropwise
over 15 minutes, keeping the temperature below 5C.
The mixture was then stirred at room temperature
overnight, and ethylphosphonic dichloride (7.35g, 0.05
mole) in dry tetrahydrofuran (lOml) was then added
over 30 minutes keeping the temperature below 35C by
cooling with a water bath. The mixture was stirred at
room temperature for 5 hours, and then let stand
overnight.
Toluene (200ml) was added, followed by water
(200ml), and the layers separated. The toluene layer
was washed with 2N aqueous sodium hydroxide solution
(lOOml), and water (lOOml) and then dried, filtered
and evaporated to give S,S-di(tert-butyl)
ethylphosphonodithioate in the form of an oil, (8.72g)
(69% yield).
The structure of the product was confirmed by
its phosphorus NMR (nuclear magnetic resonance
~33~i~
-- 32
spectrum) (single peak at 65.Oppm relative to 85%
phosphoric acid), and by its proton NMR (tetra-
metbylsilane as internal standard): [singlet at 1. 6ppm
[SC(CH3)3], two triplets at l.lppm and 1.3ppm
(P-CH2CH3) and a multiplet at 2.2ppm
(P-cH2CH3). Lntegration of the proton magnetic
spectrum was consistent with the depicted structure.
The following Example illustrates compositions
according to the present invention:-
EXAMPLE 9
A granular composition containing:-
S,S-di(tert-butyl) ethylphosphonodithioate...... 10% w/w
(weight/weight)
propylene glycol................................. 5% w/w
attapulgite 24/48 mesh granules................. 85% w/w
was prepared by mixing the S,S-di(tert-butyl) ethyl-
phosphonodithioate and propylene glyeol and spraying
the mixture through a flat-fan nozzle at a pressure of
2 bars onto the attapulgite granules, whilst mixing in
a horizontal drum blender. After all the liquid had
been sprayed onto the granules, mixing was continued
for approximately 10 minutes until the liquid had been
completely absorbed and the granules were homogenous.
The granules thus obtained may be applied at a rate of
3kg per hectare to a locus of infestation by
Diabrotica spp. to control these species.
- 33 -
Granules containing 20~/o w/w of
S,S-di(tert-butyl) ethylphosphonodithioate may be
similarly prepared.
