Chapter 4
Enhanced Biodegradation of Carbamothioate Herbicides in South Carolina
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Horace D. Skipper Department of Agronomy and Soils, Clemson University, Clemson, SC 29634-0359
Field and laboratory studies were conducted by an interdisciplinary team to: 1) confirm enhanced biodegradation, 2) ascertain microbial crossadaptation, 3) determine microbial population shifts with repeated use of carbamothioates, 4) delineate the role of plasmids, and 5) investigate chemical/crop rotations and inhibitors to prevent or improve problem soils. Bioassays and evolution of CO from C-labeled herbicides confirmed accelerated biodegradation of butylate in soils with repeated use of butylate and cross-adaptation for EPTC, vernolate, and pebulate but not cycloate. Significant increases in bacteria or actinomycete populations were detected in soils treated with multiple applications of butylate, EPTC, or vernolate. Plasmids were associated with the microbial degradation of carbamothioate herbicides by a Flavobacterium sp. and a Methylomonas sp. isolated from herbicide-history soils. Chemical rotations were c r i t i c a l in the prevention of problem soils. A minimum of two years between applications of butylate or EPTC plus dietholate was essential to insure continued herbicidal efficacy. Enzyme inhibitors began to lose their effectiveness after 3 applications. 14
14
2
Enhanced considerable described soil
by
biodégradation attention Audus
applied
biodégradation and by
recent
for
the
herbicide, by
insecticides soil
(1) soil
(6-9)
are
microorganisms.
readily
degraded
by
repeated
applications
of
in
is
pesticides years
since
herbicide
2,4-D.
also
microorganisms also The
microbes
subject
it
(2.3). to
to
first a
enhanced
Fungicides
enhanced and
received was
Diphenamid,
subject
carbamothioate (10.11)
has
(4.5)
degradation
herbicides
especially
(12-19).
0097-6156/90/0426-0037$06.00/0 © 1990 American Chemical Society
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
are after
38
ENHANCED BIODEGRADATION O F PESTICIDES IN T H E ENVIRONMENT
One
approach
problem
soils
(20).
Stauffer
leadership provided
residual
to
lives
in
of
potential In
of
1982
to
regulate,
How
in
the
farmers
or
in
the
environmentally weeds
across
multiple of
vernolate
their
in
microorganisms
are
c a n we
prove Are
they
Can
environmentally
friendly
and
be
insure
the
an
added
critical
to
been
overlooked
lemon
in
of
enhanced
life,
answer
employed basic
by whole
enhanced
as
to
during Have
make
c o u l d be
an
questions,
a
interdisciplinary field
and
plants
and
laboratory
5)
within
the or
specific
within
the
to
preserve
used
organic/inorganic
enhanced
the
biodégradation
pesticide 4
to
to
7)
When we
there the
team
of which
studies, in
a
that
are
rotations are
given
a positive
a
use(s)
microorganisms
up p o l l u t e d
number
control
6 weeks
crop/pesticide
DNA a s p e c t s
Are
chromosomes
be
Is
clean
If
culture,
enhanced
solutions?
to
or
soil
to
first
lemonade?
used
soils? on
Can
standard
Which
pure
transferred
of
the
EPTC
solutions
retard
the
potential
these
research,
assays,
soils
in
in
stable
there
for
use 4)
of
safe
biodégradation?
located
genes
and are
field?
isolated
functional
for are
b r o a d range
enhanced
enhanced and
readily
Are
a
The
tools They
producers
biodégradation--perhaps
(enzymes/genes) To
for
the soil
pesticides?
States.
same
in
as
puzzle?
perennials,
pesticides?
growth? c a n we
the
in
control,
management
can
concentration
pest(s)
crop
in
of
of Does
result
such
the
becomes
inhibitors to
adequate
specific
soil
1)
factors
against
corn,
they 6)
biodégradation? amendments
a
really
are
as the
since
biodégradation
United
degradative
or
soils:
factor
essential
degradation
community?
others
herbicides
into
effective
in
are
of
selected
addressed
biodégradation
identified
for
the
microorganisms microbial
enhanced
fit
rotation
are
responsible
plasmids?
of
are
responsible
pesticide-degraders
role
biodégradation
environmental
enhanced
If
crop
were
carbamothioate Do
Can a c r i t i c a l
butylate
the
considered
Carolina
hard-to-control
crops.
degradation
of
short
gave and
also
for use
inhibitors
and
inducers
South
role
friendly,
and
with
discussed
enhanced
southeastern
and c e r t a i n
the
herbicides
questions of
cross-adaptation
annual
genes
of 2)
herbicides
provided area
scientists
and/or
They
of
in
mask
has
this
suggested
(3)
in
inhibitors
soils. role
the
al.
as
enzymes.
a number
modify
negate
in
microorganisms
pesticides
herbicides?
does
et
of
substrates,
soil
failures?
carbamothioate
how
Kaufman
herbicides
of
performance
inducers,
"multiproblem"
or
moisture
(21)
the
biodégradation
performance 3)
al.
activity
ICI Americas)
industry earlier
resolve
enhanced
(now
had
review,
performance
herbicidal
et
certain
carbamothioate
of
microbial/enzymatic
university
specific of
this
of
to
soils.
as
enzymes
inhibitors
use
inhibitors
improve
pesticides
examples
the
agrochemical
Kaufman
degradative
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the
potential
inhibitors
restoration
been
C h e m i c a l Company
for
validation.
of
to
has
sites?
techniques used
bioassays systems
were
applied and
approach
biodégradation.
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
a^id C to
4.
Field In
Research
South
of
Carolina,
the
carbamothioate
generated Arenic
in
a
Wagram
Plinthic
respectively, corn.
In
of
these
first
in
loamy
sand sandy with
a
applications
of
annual
butylate-history
of
EPTC,
than
the
for
use
and
When s o y b e a n s dietholate indicated
the
EPTC b u t In
planted improve
not
to
vernolate
effectively
butylate
in
their
alachlor
or
metolachlor
applications
In
Piedmont
butylate of
at
detected thermic
sandy
loam
apparently sufficiently dietholate
to to
commercially gave et
Table
of
Performance EPTC p l u s
6.7 the
kg/ha, kg/ha,
Congaree
of
(24)
Treatment
of
soils
near
Butylate
2.
Butylate
of
(fine-loamy, not
in
the
Fluventic
Chewacla
soil
butylate-degraders The
efficacy
addition
of
butylate
dietholate (Sorghum
plus
after
to
be
dietholate,
SC
Control
of
in
an
and
two
Johnsongrass Congaree
(%)
6.7
93
b
43
b
6 . 7 + 1 . 1
94
b
93
a
6 . 7 + 1 . 1
98
a
92
a
dietholate 3.
EPTC + dietholate
Means
within
significantly
a
column f o l l o w e d
different
at
the
by
different
5% l e v e l
by
a I)
halepense).
planting
Clemson.
of to
(Table
Chewacla
rate
+
3-years
Aquic
the
(kg/ha) 1.
loam but
of
butylate
Chemical
of
biodégradation
found d i e t h o l a t e
4 weeks
of
consecutive
least
thermic
johnsongrass
butylate,
dietholate
at
sandy
EPTC p l u s
al.
six
soil.
the
but
biodégradation
Udifluvents)
problem
enhanced
soils,
enhanced
(turn-plow)
a
butylate-history
Data
cross-adapted
respectively. with
mixed,
level.
of
soils,
degradation
after
Carolina
restored
control
specific
reported
enhanced
population
a n d Tarn e t
soil
vernolate.
microbial
detected
Typic
overcome
of
(22)
the
and 1.7
tillage
acceptable (23)
not
in
butylate
for
Varina
butylate-history
al.
contrast,
the
excellent
al.
I.
Deep
the
application.
butylate-history
(fine-loamy,
diluted
(0,0-
butylate
the
m i c r o o r g a n i s m s were
South
rate
was
Dystrochrepts).
also
2.2 of
nonacid,
Chewacla
Tal
at
soils
an annual
butylate
mixed,
these
in
fonofos
greater
the
with
performance
in
In was
was
herbicide
in
reduced
soils.
of
with for
agree
the
et
butylate
dietholate
kg/ha
improved
efficacy
continuous
history,
6.7
(19).
Dowler
of
at
and d i e t h o l a t e
greater
results of
kaolinitic,
sanguinalis)
increased
butylate-adapted
biodégradation
annual
The
These
not
Georgia,
butylate
was
thermic
and 2-year
c o n c u r r e n t use
(Digitaria
length
were
did
(clayey, 7-
significantly
EPTC a n d g e n e r a l l y
Wagram s o i l .
herbicide
to
crabgrass
soils
siliceous,
loam
soils,
biodégradation
Plains
phosphonodithioate)
respectively.
butylate than
large
enhanced
(loamy,
Paleuldults)
diethyl-O-phenylphosphorothioate) control
of
Coastal
and a V a r i n a
(O-ethyl-S-phenylether
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evidence
herbicides
Paleudults)
thermic
and
39
Carbamothioate Herbicides
SKIPPER
letters
the
are
LSD t e s t .
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
40
ENHANCED BIODEGRADATION O F PESTICIDES IN T H E ENVIRONMENT
effective pure
inhibitor of
cultures, For
control
soybeans
and
management 2.2
was
effective
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subsequent enhanced on
the
would
address and
were
to
used
pebulate, ratio.
II.
not
the
and
in
soils
or
to
are one
it
a
key of
herbicide
issue
of
but
s o r g h u m was as
other
two
year
with
of
with
herbicide herbicide, If
soil
a problem to
soil,
a
second might
in
South
butylate-history
two
soils
at
of
were
8,
the
or
soil
preplant
12
in
plus
after
near
a
days
performance
vernolate
and 6 weeks
vernolate-history
vernolate,
dietholate
1,
measure
sites
EPTC,
herbicides
vernolate, 4
one
a problem s o i l
to
addition
to
herbicides
of
herbicides.
planted
a bioassay
Performance and
then
on
similar.
cross-adaptation The
is
residues
different
Thus,
Carolina
the
(25.) .
grower
associated
cross-adapted
two
control
insecticide,
herbicide
cross-adaptation,
i n North
and without
(DAT)
be
weed
the
and produce
of
the
dietholate, in
a
SC
Control Yellow
rate
6:1
after
planting
Sumter.
Chemical Treatment
at
yellow
vernolate
impact
a
use
of
an
of
structurally
one
the
question
potential
growers'
continuous
rotations,
potential
in
control
Fonofos,
ineffective?
just
of
efficacy
in
esculentus)
improved
of
the
cycloate.
with
2-years
crop
microorganisms
one
Grain
treatment
is
the
in
effects
investigate
incorporated
Table
adapt
for
Carolina
EPTC
component
marginal
II).
performance
and r e n d e r
generated To
used
they
same
(Table
However,
if
these
herbicide be
the
subsequent
microorganisms
gave
restoring
biodégradation
especially
of
(Cyperus a key
significantly
are
crops.
is
after
alone
in
about
nutsedge
However,
i n peanuts
When h e r b i c i d e s concerned
degradation
vernolate
Dietholate
vernolate also
yellow
vernolate
nutsedge. with
of
peanuts,
programs.
kg/ha,
microbial
respectively.
of
Nutsedge 6 WAP
4 WAP
(kg/ha)
(%)
1.
Vernolate
2.
Vernolate +
3.
Vernolate
4.
Vernolate +
dietholate
2.8
+
0.5
80
5.
Vernolate +
benefin
2.8
+
1.3
74
42
6.
Vernolate + dietholate
87
82
2.2 dietholate
2.2
+
0.4
2.8
+
2.8
+ 0.5
+
1.3
71
30
87
77
62
32 a
81
a a a
benefin 7.
Benefin
8.
V e r n o l a t e + napropamide
9.
Vernolate +
1.3 2.8
dietholate
2.8
+
+ 0.5
1.1 +
1.1
0
3
72
30
86
87
napropamide 10. Vernolate + fonofos a_ I n d i c a t e s the v e r n o l a t e versus were Trt
significantly 3 vs
T r t 4).
carbamothioate ragweed
different
Modified
herbicides.
(Ambrosia
2.8
+
vernolate at
from
the Ref.
Control
artemisiifolia)
84
4.5 plus
5% l e v e l
75
dietholate ( T r t 1 vs
means
Trt 2
or
25
of
the
was
evaluated
grain
sorghum four
and
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
and seven
a
4.
weeks
after
III,
butylate
even
at
of
use
this
reflect
may
enhanced
dietholate not
the
efficacy
of
alter
of
thermic
butylate
the
were of
used
SC-7432
inhibitors were of
microbial
applied
four
only
at
cycles
dietholate
Table
III.
1984.
these
of
butylate-history
effect
(fine,
Dietholate not
efficacy
same p l o t s
for
the
sequence of
was
eight
carbamothioate
a
total
repeated
using
cycles.
Sorghum-
7 WAT
(kg/ha) 1.
Butylate
2.
Butylate
3.
EPTC
4.
EPTC
5.
Vernolate
6.
Vernolate +
4.5 +
dietholate
4.5
+
0.7
dietholate
7.
Pebulate
8.
Pebulate
9.
Cycloate
10.
Cvcloate
4.5
+
2.2
+
0.7 0.4
4.5 +
dietholate
4.5
+
dietholate
4.5
+
0.7
4.5 +
30
a
0.7
98
0 25
a
95
a
a
8
6
58
2.2 dietholate
90
0 DAT
(%) 5
21
4.5 +
Ragweed-
12 D A T
1 DAT
rate
a
of
4 WAT
Chemical Treatment
in
NC Control
Grain
as
butylate
herbicides
Dobson.
the
disclosed),
their
to
near
and
di(3-
of
total
loamy, treated
[S-ethyl for
of
inhibitors
Treatments
for
soil
the
(26) .
the
EPTC
pebulate,
previously
(chemistry
1985, a
for
contrast,
enzyme
sand
not
evaluated
intervals
and
Thus,
microorganisms
determine or with
studies.
SC-0520
and SC-0058
EPTC,
In
of
herbicides.
SC-0058 were
In
Performance
to
alone
degradation
six-week
in
related
The with
soil.
vernolate,
A Dothan loamy
for
(diallylamine)
of
Paleudults)
inhibitors,
of
conditions.
conducted
butylate
Plinthic
than
this
butylate-degrading these
EPTC.
associated
butylate of
Table sorghum
performance
and c r o s s - a d a p t a t i o n
performance
to
chloroallyl)thiocarbamate), and
for
in
grain
than
efficacy
these
the
shown the
improved the
greater
butylate
As
control
effective
improved
butylate.
was
experimental
less
under
experiments
to
butylate-history
indicate
applications
siliceous, with
the
cross-adapted
Field multiple on
The
apparent to
was
relatively
d i d not
cycloate
failed
significantly
biodégradation
readily
were
was
respectively.
along
and EPTC.
dietholate
or
(WAT),
a n d EPTC
dietholate
butylate
was
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treatment
1 DAT a n d b u t y l a t e
addition both
41
Carbamothioate Herbicides
SKIPPER
71
a
96
61
38
100
62
48
100
80
52
99
90
66
76
41
85
78
32
74
a
indicates the herbicide versus herbicide plus dietholate means were significantly different at the 5% level (Trt 1 vs Trt 2 or Trt 3 vs Trt 4) Adapted from Lawrence, E . G . et a l , Weed Science, in press.
Bioassays cycle.
were
performance Results was
planted
Non-treated on a
weekly were
first-time
indicated
initiated
at
plots
with
a
that
intervals included
after to
application basis enhanced
second
each
in
each
biodégradation
application after
application
evaluate
just
butylate
cycle. of
six
butylate weeks
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
and
42
ENHANCED BIODEGRADATION O F PESTICIDES IN T H E ENVIRONMENT
that
i n h i b i t o r s were
control Cycle
levels.
5 while
(Figure
1).
SC-0058 began SC-0520
biodégradation
(26).
for
various
periods
of
Another
approach to
rotations. was
of
In
rotations
on
evaluated corn
in
enhanced
herbicide
herbicide
butylate,
lose
in
were
the
other
not
effective
was or
continuous rotation,
plus
use
with
inhibitor enhanced
chemical/crop
herbicides
and
crops
of
these
treatments
were
the
effect
c o r n and h e r b i c i d e , rotation
Herbicides
dietholate,
7
inhibitors
of
of
Sixteen
and crop
in
Cycle
as
reduction
evaluate
biodégradation.
in
(27.28) .
the
study
initial
decreased
an e f f e c t i v e
soils
to
exceeding
efficacy
involves
five-year
or
dietholate
its
prevention
rotation.
EPTC
of
Dietholate
time
a
restoring
a Dothan s o i l
including
with
with
to
pesticides
1984,
established
in
effects
and SC-7432
of
biodégradation
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effective
Inhibitory
continuous
(corn/soybeans)
investigated
alachlor,
included
vernolate,
and
trifluralin. The two
efficacy
annual
annual or
of
EPTC p l u s
applications
applications
alachlor
in
(Table
soybeans
control
was
soybeans
in
rotation
performance rotation to
of
away
EPTC p l u s
development
critical
Table
to
IV.
the
Control as
the
of
large
crabgrass by
crop
or
because
EPTC p l u s
years prevent It
was
consecutive
dietholate
in
rotations
of
1984
in
required
(Table V ) .
Control
Herbicide
three and to
by
large
subsequent
products
and h e r b i c i d e
Rotations Crop
the were
rotation
corn
of
dietholate
these
five
in
vernolate
to
Two
after
after
degree
of
biodégradation
herbicide
affected
(29).
of
decline
alachlor
a high
detrimental
EPTC p l u s
enhanced
to
of
Inclusion
dietholate
performance
of
maintain
corn
rotation,
was or
began
ineffective
By i n c l u s i o n
maintained.
from b u t y l a t e
m a i n t a i n adequate
the
totally
IV).
in
crabgrass
the
dietholate
a n d was
large
crabgrass
1986
1988
Corn
EPTC
95
a
(%) 73 b
8
c
Corn
EPTC/alachlor
78
ab
95
a
70
a
Corn/soybean
EPTC/alachlor
94
a
100
a
79
a
48
b
Corn/sovbean 94 a EPTC/vernolate 69 a b a a column followed different letters by Means within s i g n i f i c a n t l y d i f f e r e n t a t t h e 5% l e v e l b y t h e L S D t e s t . EPTC p l u s
dietholate.
applications control.
of
in
dietholate
than
also
was
rotation
of to
from
of
enhanced
EPTC p l u s
with
dietholate
of
of
herbicides
or
gave
or
butylate
vernolate,
Rotation the
29.
alachlor
biodégradation.
under
prevent
Ref.
included
performance
rotations
important
(13.18.27.30)
or
herbicide.
than
retardation
that
better
carbamothioate effective
butylate
Rotations
resulted
Modified
are
poor
and
EPTC
a
closely
the
crop
in
the
Rotations
midwestern
United
alleviate
enhanced
weed
trifluralin plus
related was
less
prevention of
States
or
herbicides conditions
biodégradation.
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
43
Carbamothioate Herbicides
SKIPPER
1001 2 Β Β
A P P L . B U T Y L A T E (Β) APPL Β + SC-0058 + DIETHOLATE
80-
Έ
X
(D
70-
OC
Ο (/>
60-
Ζ
the
analytical
soil
to
degradation
and
rapidly
I
soil
applied
degraded
Varina,
of
assess
greater
biodégradation is
increased
butylate-history no
as
butylate-history
non-history
Butylate
control
defined
C-butylate the
been
non-butylate-history
^or
which
history
on
(11)·
research
of
general,
studies
are
LSD
chromatographic
environmental
the
in
the
to
microbiologv^herbicide
herbicide
by
i n c l u d e d measurement
delineate
determine
laboratory
involved
C-labeled pesticide
use
letters
29.
Studies.
fyther
from
at
by
Research
biodégradation while
followed
different
from
Laboratory
column
vernolate not
evolution
in
use
cross^-adapted of
CO
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
both (25). for
(Table
Carbamothioate Herbicides
Downloaded by UNIV OF MASSACHUSETTS AMHERST on June 3, 2018 | https://pubs.acs.org Publication Date: May 3, 1990 | doi: 10.1021/bk-1990-0426.ch004
SKIPPER
Time (days) Figure
2.
without
prior
Means
Accumulation butylate
followed
significantly
(Reproduced with Sci.
Soc.
by
the
different
of
use
C0< e v o l v e d 2
and
same at
permission
the from
treated letter 5%
15.
so^ls
with
within
level
Ref.
from
by
with
and
C-butylate. a
day
the
Copyright
are
LSD 1988
Am.).
Racke and Coats; Enhanced Biodegradation of Pesticides in the Environment ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
not
test. Weed
46
ENHANCED BIODEGRADATION O F PESTICIDES IN T H E ENVIRONMENT
VI).
Overall,
and
there
cross-adaptation for
vernolate
confirmed At
Table
various
been
a
good
for
pebulate
on
the
field
However,
micr^ooganisms
based
poor
in
CO^ a s s a y s
i n c o r p o r a t i o n or
b l a m e d as
3
Cross-adaptation butylate-
between
the
Dothan
has
soil
not
been
conditions.
times, been
agreement
cross-adaptation.
butylate-adapted
field
have
VI.
of and
under
conditions
Downloaded by UNIV OF MASSACHUSETTS AMHERST on June 3, 2018 | https://pubs.acs.org Publication Date: May 3, 1990 | doi: 10.1021/bk-1990-0426.ch004
has
l a b o r a t o r y assessments
causes
for
for
adverse
environmental
performance
carbamothioate
or v e r n o l a t e - h i s t o r y
failures
herbicides
by
in
soils
Soil herbicide history
Soil
Herbicide Cvcloate
Butvlate NA
x
Butylate
Varina
NA
X
NA
X
X
X
a
Dothan
Butylate
Wagram
Vernolate
Dothan
X
X
Vernolate
Vaucluse
X
X
Cross-adaptation herbicide b
in
degradation
is
defined
the
in
a
butylate
when
of
factors
microorganisms
responsible
although degradation expected microbial can
the
To
is
of
that
investigate 25,
50,
or
10
a n d 25% F C ,
80
to
90%.
soil
FC for
(25).
moisture
of
the
20
below
3% a n d
Pesticide-treated time
before
soils,
one
storage.
To
they wonders
in
CO
a
if
they this
provides
the
suitable a
below
for
pesticide disease,
the
Wagram
of
of
threshold
lose
regulates
moisture soil 0.05
total
Similar
moisture
vernolate
in
of
was
EPTC of
soil
stored
a
or
their
-5
to
kPa) .
reduced
by
between
50
effects
were
vernolate-history
moisture for
enhanced
dependent above
various
laboratory studies.
question,
2
soil (22.) .
adjusted
bars C0
soil
on
was
C - b u t y l a t j e was in
or
conditions,
butylate-history
soil
from
may b e in
that
dry f i e l d
a non-butylate-history
(35).
rate
used
are
herbicide
insect,
factor
Under
differences
soils
the Thus,
failure.
independent
are
address
is
butylate-history
degradation
Degradation
of
more
(weed,
population
in
days
culprit.
microorganisms
herbicide
fiel