Enhanced Biodegradation of Pesticides in the Environment - American

Chapter 5

Enhanced Biodegradation of Dicarboximide Fungicides in Soil Allan Walker and Sarah J. Welch

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Institute of Horticultural Research, Wellesbourne, Warwick, United Kingdom

Experiments in the mid-1970's demonstrated excellent control of white rot disease of onions with iprodione. There is increasing evidence that in commercial practice the fungicide becomes less effective with repeated use and this has been linked with enhanced degradation in the soil. In a survey involving 33 soils, a clear relationship was established between the rate of degradation and the frequency of prior application. The related compound vinclozolin is also prone to enhanced degradation and there is evidence for cross-enhancement between iprodione and vinclozolin. Rapid degrading ability can be readily transferred to slow degrading soils by inoculation with small amounts of rapid-degrading soil, and rapid degradation can be inhibited by soil sterilization or treatment with anti-bacterial antibiotics. Studies of the pathway of degradation have led to development of a simple colorimetric test for identification of soils with rapid-degrading ability. Mixed cultures of bacteria capable of degrading the fungicides have been isolated and there is preliminary evidence of plasmid involvement in degradation. The

phenomenon

of

enhanced

repeated

application

with

phenoxyalkanoic

the

(1.2).

Although

pesticides practical

it

importance of

following

correlated

with

(see

reviews

minor United

but

by

none

Kingdom

is

the is

has

recently

become use

at

degradation Kaufman

important

apparent

pesticides

2,4-D,

been that

in

the

following late

2,4,5-T

observed

with

direct

biological

insecticides,

fungicides

of

(6);

same

has

now

their

residues

Suett

and Walker

example

failure

site

of

of

this

in

and been

the

soil

(7)).

problem

dicarboximide

MCPA

other

of

Poor

the

1940's

and

consequences

apparent.

soil-applied

(5);

of

observed

herbicides

repeated

less the

first

behaviour only

enhanced Roeth

was

acid

have

several

herbicides

biodégradation

soil

similar

(3.4),

performance

to

in

A the

fungicides

0097-6156/90/0426-0053$06.00/0 © 1990 American Chemical Society

In Enhanced Biodegradation of Pesticides in the Environment; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

54 to

ENHANCED BIODEGRADATION O F PESTICIDES IN T H E ENVIRONMENT

c o n t r o l white

onions.

rot

The o n l y

adequately

disease

(Sclerotium

cepivorum

commercially available

controlling

this

disease

in

[Berk.])

of

capable

of

fungicides

the

U . K . are

iprodione

(3-

(3,5-dichlorophenyl)-N-isopropyl-2,4-dioxoimidazolidinecarboxamide)

and v i n c l o z o l i n

((RS)-3-(3,5-dichlorophenyl)-5-

ethenyl-5-methyl-2,4-oxazolidinedione). failure

of

fungicide

iprodione had been

similar

observations of

to

investigate


the

in

methods

c a n be

Brown and E n t w i s t l e

Performance

Before

discussing

at

changes

the

i n Walker,

observed

in

from

experiments

the in

a

Iprodione

been

since

experimental

(IHR),

1983,

plots

although

during

it

this it

1984.

of

gave

these

experimental

with

is

at

(10),

I

the

some

rot

looking

that

have

summarise

results

Institute

of

a number o f

since

Myclozolin

Iprodione

worthwhile

over

site

the

few

(12.13).

Table

facility

at

past

and Dearnaley

Wellesbourne

ineffective

summarises

the

onion white in

the

reported

b i o d é g r a d a t i o n of

Observations

The d a t a

reported where

(9)

paper

and Walker

against

quarantine

Research

vinclozolin

Entwistle

(8)

site

over

details

degradation,

field.

Horticultural

This

Full

and P r e l i m i n a r y

a

and E n t w i s t l e

enhanced

(11),

fungicide

at

Wellesbourne

soil.

i n performance

been

has

at

apparent

Walker, Field

Entwistle

disease

vinclozolin.

made

fungicides found

the

repeatedly,

with

experiments

dicarboximide

control

used

results years

to

1981

control

years.

and in

the

(3-(3,5-

dichlorophenyl)-5-methoxymethyl-5-methyl-l,3-oxazolidine-2,4dione)

and procymidone

(3-(3,5-dichlorophenyl)-1,5-dimethyl-3-

azabicyclo[3.1.0]hexane-2,4-dione) only

and not

former gave

has

good

tested

Table

available

given

good

control

in

are

commercially control

one

over

experimental

for

white

rot

a number o f

experiment

in

1984

fungicides

control.

years;

and has

the

not

The latter

been

subsequently.

I.

Changes

in

Effectiveness % reduction

of

Dicarboximide

i n white

rot

Fungicides

infection

in

year:

1985

1986

Fungicide 1978

Iprodione

Procymidone

As studies

part

of

changes were

99

31

0

0

13

0

86

85

0

76

5

7

-

97

100

100

97

97

-

-

100

-

-

-

Myclozolin

the

1981

93

Vinclozolin

for

1979

a in

made

series

-

of

fungicide

1982

experiments

to

performance,

i n i t i a l l y with

1983

1984

investigate laboratory

iprodione.

the

0

reasons

degradation

Carbon-14

labelled


5. WALKER & W E L C H iprodione field

was

degradation the

same

was

that

(10).

to

50%

loss

differences from four

treated

of

problem with soils

were

they

were

treated

these

samples.

consistent Further

is

order

to

taken

Sequential field

of

enhanced

of

more

applications

monitored.

results

c a n be

gave

vinclozolin the

treated

are

at In

loss

(100

days), none

were

samples

of

6.5

to

those

further from the

started

Station,

texture the

fungicides degradation incubation

samples

detail of

either

period.

1.

In was

recovered

(50

days), for

remained

soil

2 days for

pH on

made

a

at

Rothamsted

the

(12).

fungicide

at

D e g r a d a t i o n was

long-term

The s o i l s but

water

for

was

4.3,

fungicide

procedures The r e s u l t s

more

or

5.0

rapid

were

at

of

with liming

of

pH measured

carbon-14

pH 4 . 3

later,

degradation

were

of

involved

for

time

vinclozolin

field

used

23

49

time

third

plots

content

about

after

the

the

from

soil

1).

experiments

England.

The

and those

iprodione

was

(11).

and

cm o f

radioassay

by Walker

Figure

(Figure

distilled

The experiments

of

were

experimental

The r e s u l t s

of

with

laboratory

Sawyers

matter

in

and a p p r o p r i a t e in

dose

soil

related

degradation

time

influence 10

the

the

When t r e a t e d

Harpenden,

soil

different

experiments. described

of

second

laboratory in

in both

iprodione

dose

7 days.

top

1961

a

degradation

of

both

50% l o s s

iprodione

and o r g a n i c

suspension in

in

using

Brown and E n t w i s t l e

applied

the

although

enhanced

made w i t h

applied

after for

of

reproduced i n

the

the

made

enhanced

5 days.

10% o f

recovered

soil

Experimental 1:2.5

for

to

iprodione

fungicides.

rate

that

for

the

and v i n c l o z o l i n ,

experiment similar

time

2% o f

treated

examine

iprodione

the

reduced only

was

similar

To

0,

than

soil was

to

and

pre-

conclusive.

made

were

in

description

are

that

of

were

were

indication

and boundaries

and V i n c l o z o l i n evidence

i n Walker,

One

respective

not

used

'untreated'

results,

dicarboximide

A full

susceptible

the were

iprodione

experiments

time

and l e s s

days.

and

clear

laboratory

days 50%

a

their

soil

previously-

areas.

the

indicated

hence

experiments with

that

in

fungicide

from the

headlands

evidence (14)

of

found

was

pH t h a n

and changes

compound v i n c l o z o l i n .

soils

from f i e l d

S i m i l a r experiments

procedures

in

from u n t r e a t e d

The

respectively.

had been

The

in

soil.

observed

pathogen.

definitive

treatment

experiments

iprodione

Iprodione

iprodione,

days,

were

degradation,

with

30

rates

the

lower

and

of

the

degradation

where

experiments

Published

obtain

known p r i o r

and

early

Observations

farms

10

of area

with

previously-untreated

quickly

pH dependent

with

degradation

rapid

than

rate

grassed

more

the

control

more

from a

indicated in

fields

generally

soil

IHR q u a r a n t i n e

treated

degradation

consistently

degradation

In

the

in

approximately

to

degraded

areas

that

the

and the

been

than

in

of

ineffective,

previously

commercial

occasions

consistently

no

had not

were

from an area

was

The r e s u l t s

samples

several

soil

compared w i t h

Similar on

in

fungicide

previously-treated

times


the

field

fungicide the

incubated

i n which

55

Dicarboximide Fungicides in Soil

5.0,

in 5.7

a and

degradation

labelled which

were

indicated

little

d u r i n g an

80-day

pH 5.7

and


the



Days Figure soil. and

1. #

100

days;

Δ

Degradation

residues days;

Ο

treated

(Reproduced with Society

of

after

initial

(a)

iprodione

of

following treated once

sequential

once

only

permission

Chemical

only

after

treatment and

(b)

after

at

time

pre-incubation

pre-incubation

from Ref.

vinclozolin

treatments

11.

for

100

Copyright

in

0,

for

50 50

days. 1986

Industry).


5. WALKER & W E L C H times 75

for

days

with

to

initial 5.7


rate

in

with

successive

for

vinclozolin.

and

4

for

vinclozolin,

with for

the

Although

enhanced

the

are

enhanced

with

under

available a

for

a

when

and

the

in

for

fungicide.

Figure

50%

loss

and

of

in

In

22

to

were

7

the

was

II.

was for

in

can

made,

the

extent

commercial

to

field

Previous

of

of

soils

for

were

time

to

a

evaluated

90%

Data

for

from Ref.

12.

33

Soils

Copyright

Industry) for

90% l o s s

(days) ±

mean

S.. D .

12

22

93

50

2 3 . .7

One

5

16

28

20

4 . .9

Two

4

5.2

23

17

8. 2

Three

3

3.8

15

7.8

5. . 8 3

9

4.8

13

8.1

3..21

None

than three

results

are

minimum a n d mean DT90

summarised is

in

presented

Table for

was

repeated

soil.

maximum

minimum

at

iprodione been

data

Degradation

Time

33

measured

vinclozolin

opportunity

each

Chemical

had

whereas

the

permission

Number

treatments

and

for

Iprodione

Society

the

to

of

from

moisture

fungicide

years,

(12)

estimated

Summary o f

soil

restricted

this

samples

collected

degradation

The d e g r a d a t i o n

procedures was

were

(20°C; was

and hence

(Reproduced with

The

be

and

commercial

performance,

use

iprodione

several

much l e s s .

1987

of

conditions

treatment

(DT90)

iprodione

rates

study

new

in biological of

The e x p e r i m e n t

curve-fitting

degradation

More

12 and

days.

laboratory

in

2b

30,

Fields

determine

induced

from

respectively, and

the

control

at

and


in

order

been

iprodione

Commercial

soil

disease

has

iprodione

30,

limited soils

results

of

iprodione to

The

for doses

after

degradation

2a

third

approximately

of

laboratory

commercially

application

Table

were

change

-33kPa).

relatively

using

either

widespread.

sites

of

because,

only

in

of

6.5 When

days

the

and

pH

hence

standard

tension

s t i l l

increase

second

known h i s t o r i e s

different

was

200

a progressive

degradation

potential

soil

there

60

at

compounds.

and in

times

lack

both 100

However

application

with

for

soils

about

rapid

soils.

degradation

not

were

e v e n more

days

the

acid

shown

first,

repeated

and

35

to

Enhanced Degradation

problems

practice

are

they

to

started,

more was

The

for

induced by

30 made

doses

pH 6.5

Evidence

soils,

two

there

soil

days

of

were

the


D e g r a d a t i o n was

i n c u b a t i o n was

and 6.5,

field,

iprodione

50% l o s s

the

which

of

applications

degradation pH

loss

respectively.

times

repeat the

50%


II

where

the

each

group

of

maximum, similar


58


pretreatment varied

previously which

had been

These

results in

phenomenon (DT90

4-5

days

with

iprodione

and

in

A

Color of

the used

to

performance important

liquid

demonstrated

that

concentrations colorimetric complex

was

test

examine

at

50

mg/kg

in

obtained was

positive

was

extracted

III.

i n which those

with

The

in

test

enhanced

degradation

i n which

efficacy

time

has

is

the been

the

high

diazo

color

3,5-

test

was

after 90%

after and

DT90

potential induced be

days

degradation

days,

with

above.

3

7

a

of

illustrated

might

used

incubated

described

to

an

A

reaction 14

was

and

of

made

than

has

and

high

iprodione

the

problems

Other Dicarboximides

further

The

obtained

clearly

In and

survey

from

identical

from

field

thin-

its

product

ug.

associated

was

and

from

an

amounts

less

result

Table

soils

a magenta

extracts

of

the

rapid.

D T 9 0 was days

use

analytical

relatively

A positive

10

the

The

soil,

was

15

i n which

of

in

of

6 days.

type

data

of

to

acetone

after

The

in

production

from the

soils the

biological

Soils

involved

in

between

from 2

in

than

of

3,5-dichloroaniline

degradation

reaction days.

Studies

range

those

degradation

loss

gas-liquid

on p r o d u c t i o n

soils

less

of

common

fungicide

iprodione

when

22

identify

33

parent

that

of

obtained

than soils

of

differentiate

reaction

with

iprodione

days

the

color

a

rapid

3,5-dichloroaniline.

c o u l d be

the

soils

degradation

is

for

chromatographed

3,5-dichloroaniline

A positive of

in

most

above

confirmed by

iprodione

to

use

in

occasions.

The m a i n d e g r a d a t i o n

product

based

shown

dichloroaniline to

it

the

treated

more

enhanced

repeated

extraction

chromatography

when

or

and v i n c l o z o l i n .

(10_,_12) .

degradation

that

disappearance 8 days

Rapid-Degrading

solvent

(13)

about

potential

separation

unlabelled

Walker

to

three

summarized


pure,

experiments,

Identify

involved

90% been

organism.

iprodione

products

iprodione

manner

was

to

on

clear

to

had not

field,

showing

a

target

chromatographic

degradation both

is

experiments

labelled

techniques layer

Test

the

following

soils

there the

in

time

that

demonstrate

soils the

T h e mean soils

previously

therefore field

days),

carbon-14

the

treated

against

Simple

soils. in

iprodione

activity

Several


history

f r o m 50

less

by

to

the

indicate

and hence

to

encountered.

Possibility

of

Cross

Enhancement As

mentioned

in

the

previously,

U.K. for

iprodione control

control

determine

Table

whether of

I)

they

has

i n Wharf

the

a

6.9.

sandy

Duplicate

myclozolin

or

Other

disease

related

of

enhanced

prone

been

clay

procymidone

field

at

2.1%

sprayed with at

4.0

kg/ha

onions

give

made

Field

iprodione, on

three

The

different

plots

matter

good

to

degradation. between

were

IHR W e l l e s b o u r n e organic

approved

are

can

therefore

degradation

investigated. a

loam w i t h

were

to

of

fungicides

fungicides

may b e

Ground,

plots

rot

were

also

established

dicarboximide

and experiments

cross-enhancement

dicarboximides is

two

white


(e.g.

possibility

soil

the of

in

which

and pH

of

vinclozolin,

occasions

-


23

5. WALKER & W E L C H May,

3 July

control each

plot

with

the

Table Time

and

5 August

plots. on

Samples

2 April

different

III. for

1986. of

1987

also

from the

as

taken

3

7

days

5 cm

were

(12).

The Test

after: 10

days

days

*** *** *** * ** **

*** ***

6.0

*** *** ***

10.4

+

11.1

*

14.5

0

15.8

0

+

17.6

0

19.1

0

22.0

0

+ + +

* * **

24.6

0

0

0

33.1

0

0

0

4.9

indicates

no

color

change;

+

indicates

of

magenta

a

of

incubated

the C o l o r i m e t r i c

response

Color

unsprayed top

previously

Soils in

loss

two

subsamples

described

of Different

3.8


T h e r e were were

and separate

(days)

0

soil

fungicides

Reaction

90%

59


**

***

slight

pink

coloration; *,

* * and * * * i n d i c a t e

5,

5-10

a n d >10

decline

in

for

liquid

myclozolin enhanced

extremely

levels

3,5-dichloroaniline

fungicide

performance with

ug

residues

and procymidone

degradation

stable

in

of

this

occurred within

Procymidone

was

been

remained

treated

generally evidence be

by

in

Examples are

shown

in

in

with

repeated

in the of

all

the

by

before

(Figure

3)

60

soil day

field

those

in

or

and o n l y and of

which

is

evidence was

period.

50% o f

These of

the the

data

There

However,

high

results

15-20%

whether

not. I.

or

Myclozolin

performance

application.

to

The

p r o v i d e d no

incubation

Table

biological

experiments

gas-liquid

fungicide.

irrespective

the

equivalent

(11,12).

a n d b e t w e e n 40

days

show w h e t h e r

control

stability

60

previously

as

either

stable,

after

consistent to

affected

good

also

measured

particular

degradation amount

was

chromatography

color

respectively.

is

initial soil

insufficient

procymidone

myclozolin

consistent

had

are

with

may

gave its

high

soil. the

Table

data

IV.

from the

These

are

cross-enhancement the

residues

experiment

measured

14


and

28


60


20

40

60

100

80

Incubation Figure

2.

iprodione treatment; with

Degradation and •

(b)

Chemical

treatment;

from Ref.

12.

in Δ

40

60

100

80

(days) applications

soil

with

third

of

treatment.

C o p y r i g h t 1987

(a)

Ο

pH 6 . 5 .

first

(Reproduced

Society

of

Industry).

100

80 -I CO •H -P •H β •Η

time

sequential

vinclozolin

second

permission

of

20

ω

Sa

S

60

Ο

40 i 20 0) I

I

20

I

I

40

I

Incubation Figure

3.

previously

Degradation

of

treated

)

( Δ

(a)

I

60

1

20 time

ι

I

60

(days)

procymidone

and p r e v i o u s l y

ι

ι

40

and

(b)

untreated

myclozolin (

#

)

in

soil.


5. WALKER & W E L C H days

after

that

degradation

prior

the

start

treatment

respectively. myclozolin

of

the

both the

incubation

iprodione

soil

with

discussed

procymidone

rates

of

iprodione

above,

or

have

a major

additions

of

of

the

degradation

was

evidence

significant

cross-enhancement

iprodione

and v i n c l o z o l i n ; by pre-treatment

Vinclozolin

degradation

of

with

the

soil

observations treatment

where the

systems

will

be

IV.

to

Cross

with

affected which

only

agrees

affected There

way

to

to

isolate for

the

a

the

chemicals, extent.

involved was

apparently

by

extent

by

no

concerned,

a better

pretreatment

previous

therefore,

specific

with

on

small

slightly with

is

by

vinclozolin.

some

are,

gain

to

degradation

soil

cross-enhancement

only

responsible

Table

was

and a l s o

relationships phenomena

the

myclozolin.

probable

that

iprodione of

iprodione,

(12.),

with

affected

soil

same

procymidone of

indicate

enhanced

effect

although only

They is

vinclozolin

pre-treatment

d i d not

subsequent

experiment.


The

enhanced


of

of

As

or

degradation


prior

simple and

it

is

understanding

organisms

and

of

such

enzyme

degradation.

Enhancement

between D i f f e r e n t

Dicarboximide

Fungicides

Pretreatment

Concentration

Fungicide

Iprodione

After

1

(mg k g " )

of

Vinclozolin

14

days

fungicide: Myclozolin

Procymidone

incubation

None

6.00

5.45

5.85

Iprodione

0.15

5.50

5.90

Vinclozolin

2.30

0.05

4.27

Myclozolin

7.93

5.39

5.44

6.72

Procymidone

4.97

5.45

5.55

4.86

After

28

days

6.82 6.81 7.48

incubation

None

3.75

2.44

5.20

5.71

Iprodione

0.00

1.89

5.46

5.80

Vinclozolin

0.18

0.00

3.96

6.25

Myclozolin

3.96

2.37

5.15

6.10

Procymidone

2.88

2.31

5.08

3.12

Ease The

of

Induction

loss

of

quarantine chemical

is

and

control field

of

Spread white

summarized

apparently

rot in

inactive

disease

Table in

I

all

is

by

iprodione

widespread

parts

of

the

in and

the the

field.


IHR

62


However, trials will

have

been

treated

of for

readily

moved

how

soil

rapid

only

the

It

with

soil

to

of

transfer

of

degrading

degradation

is

influenced

field

in

are

rates

has

scale of

developed

the

degrading

It

the

is

that the

field

a n d how

the

pre-treatment

to

or

possible

bring

drift

made

ability

wind

also

r e q u i r e d to

of

field the

that

so

field

the

raises

blown with

therefore

ability, by

is

parts

were

This

may b e

chemical

effects

Experiments

small area

operations.

degradation

deliberately.

to

limited

that

cultivation of

refer a

fungicide. the

amounts

leads

only

throughout

subsequent

application

Table I

with

transferred trace

in

one

degradation.

during routine

change


in

year

in

capacity

that

results any

that

question is

the

so

about

a

during

not

treated

examine

induction

the

of

concentration

ease

rapid

of

fungicide. Samples collected was of

untreated the

incorporated 8 mg/kg.

treatments before

high

and

indicate the

indicating

a very

soil

of

Further

further

a

0,

under

g)

concentrations

of

the

difference

in

degradation

0,

0.05

or

concentrations subsequent after the

therefore the

soil

able

were

to

more

than

to

enhance and,

experiment

less

10.0

low

Wharf at

5.0 to

in

described

was

the

with

that

in

measured

between

5)

but

10.0 of

and

residual

during

the

little pre-incubated

pre-treatment

the

initial

effect

this

dose.

The

with

above,

to

help

of

subsequent those

explain

0.50

13

mg

days

amounts.

at

conjunction

on

with

initial

concentrations of

were

the

concentrations

5% o f

samples

samples

samples

concentrations soil

mg/kg.

the

The

significant

residual

site

initial

indicate

soil

had a

Ground (12).

or

all

conditions

biodégradation

taken

soil soil

into

before

mg/kg.

(Figure

than

85% o f

that

the

as

added

were

this

residual

demonstrate

soil

identical

1.0,

iprodione,

the

rate

was

control

Following pre-incubation

more,

treatments,

fungicide

mixing'

loss.

or

re-incubation

other

equivalent are

of

by

ability.

iprodione

was of

results rate

the

(Figure

pre-treated

from the

standard

than

rate

0.50,

soil

mg/kg

greater

rates

iprodione/kg

The

0.10

soil

fungicide

days.

intervals

mixture

the

degrading

contained

same

21

with

the of

of

incubated

degradation

the

pre-treated

conditions

0.10,

in

subsequent

of

at

100%

were

The r e s u l t s

in

of

and

soil.

iprodione

the

0.1%

concentration

soils

iprodione soil

a

10.0

the

(12).

degradation

0.05,

concentration

re-incubated

5.0,

were Iprodione

experimental

measured

in

the

control

(500

After

give

a

of

standard

of

to

were

just

transfer

of

under

days,

of

rapid-degrading

amounts

1.0,

at

give

A l l of

increase

more in

concentrations 70

0.5, soil.

soil

above.

soils

to

degrading-ability

ready 5% o r

samples

incubated

Duplicate

the

resulted

pre-treated

both

mixed

rapid-degrading

alter

Incorporation

of

pretreated

described

chromatography

Incorporation to

site

then

0.1,

a progressive

increased.

iprodione

residues

liquid

sufficient

were

0,

iprodione

proportion of

control

were

rapid-degrading

performance

as

and

Ground

subsamples

soils

containing

4)

the

Wharf

into

The

pre-treated as

of

from

time

In

were

results iprodione additions

from the why

of 'soil

enhanced



5. WALKER & WELCH

0

63


4

12

8

16

20

24

28

Incubation time (days) Figure 4. T r a n s f e r of iprodione degrading a b i l i t y , • c o n t r o l s o i l ; φ d e g r a d i n g s o i l ; Δ , A and • r e f e r to 0 . 1 , 0.5 and 1.0% o f d e g r a d i n g s o i l mixed w i t h c o n t r o l s o i l . 5 and 10% degrading s o i l i n c o n t r o l s o i l gave r e s u l t s i d e n t i c a l w i t h d e g r a d i n g soil ( • )·

12

J

0 Η

1

1

4

8

τ-"

12

r

1

16

20

24

Incubation time (days) F i g u r e 5. E f f e c t of pre-treatment c o n c e n t r a t i o n d e g r a d a t i o n o f subsequent a d d i t i o n o f i p r o d i o n e . i n i t i a l c o n c e n t r a t i o n o f 5 mg kg" i d e n t i c a l w i t h 10 mg kg-" . 1

1

(mg kg" ) on Results for t h o s e shown f o r

1


64


degradation field Effect In

of

of

order

Microbial to

assessment

of of

experiments inhibitors samples

of


Subsamples mg/kg

or

dry

soil)

and

to

soil

(1

an

so

moisture

bar)

and

the

the

With

the

or

changes

results

Figure

responsible

for

similar

studies

of

these

authors

the

currently

in

was

very

low

of

being

of

difference

that

soil

or

particularly markedly

there

growth

is

no

although

of

some

soil

significant In

general, may b e

been

the

primarily

reported

The

rate

that

from

treated

in

soil.

carbon-14 soil

labelled

dioxide

with

to

that

of

these

bacteria

in

previously

of

incubated

Carbon-14

basis

both

gamma-irradiation

(15). to

was 6.

from

soil

observations,

were

responsible

insecticide.

of

studies

degradation

soil

residues


similar

On the

concluded the

in

and

(0.33 intervals

Figure

little

bacteria

soil.

and

with

at

in

although

6 have

similar

20°C

33kPa

cycloheximide

isofenphos

control

at

of

antibiotic,

iprodione

kGy)

degradation

inhibit

soil

50

was

may c a u s e

biodégradation

autoclaving. also

The

mg/kg by

appropriate.

analysis

communities.

that

insecticide

was

Studies

detailed

enhanced

in

cycloheximide

degradation

fungi

from l a b e l l e d

incubated

by

Preliminary

those

with

this.

Figure

with

from

iprodione

8

sterilised

inhibitory,

soil

sterile was

dose,

as

mg/kg then

was

in

fungicide were

mg/kg

500

were

fungicide

azide, less

of

may a l s o

indicate

enhanced

chloramphenicol

was

in bacterial 6

of

(800 500

lost

summarised

of

for

soil

for

there

sodium

of

treated

sterilized

rate

of

inhibited

fungicide,

soils

incubated

results

with

azide

water

pressure

removed

involved

above.

suspension

U.K.;

Analysis

the

between

of

were

to

evolution

evolution

days.

reasons

the

microbial

more

antibiotic, The

soils

applied

some

once

sodium

vinclozolin

degradation

dioxide

insecticide

were

anti-fungal,

population in

g)

Treatment

removal

same

soils

Cycloheximide

the

and

preliminary

antibiotic,

7 days.

Swindon,

or

an

with

degradation

predominantly bacteria,

the

to

one

effects

of

for

procedures

any

with

(anti-fungal

pic,

the

25

(12)

sterilization

indication

Results

all (100

vinclozolin.

reduced

More

of

subsequent before

inhibitory

for

treated

to

a

pre-treated

concentration

iprodione

equivalent

chloramphenicol.

in

in

involved, of

described

vinclozolin

of

(Isotron

as

treated

dry overnight the

may b e

site

field

make

influence

(anti-bacterial

or

to

experiments

Ground

the

20°C

samples

subsamples

fungicides.

with

spread

contribute

and

that

the

The

were

at

that

with

amounts

soil

HPLC as

in

kg)

air

Further

incubated

during

organisms

Wharf

iprodione

gamma-irradiation

in

and

Degradation

determine

loss.

incubated

water

Duplicate

of

on

cycloheximide

lightly

soil.

All

induced

microorganisms

chloramphenicol

with

distilled

of

to

from the

soil),

soil)

replaced

soil

vinclozolin

dry

by

easily


groups made

rates

of

dry

allowed

the

soil or

that

iprodione

were on

iprodione

then

is

Inhibitors

confirm

degradation

dry

iprodione

soils.

Microbial of

of

the the

undertaken

Relationships

microbial

relationships

dicarboximide in

the

fungicides

Department

of

the

involved

in

in

are

soils

Environmental


Dicarboximide Fungicides in Sod


WALKER & WELCH

5

10

15

I n c u b a t i o n time

20

25

(days)

F i g u r e 6. D e g r a d a t i o n o f (a) v i n c l o z o l i n and (b) i p r o d i o n e i n r a p i d d e g r a d i n g s o i l ( φ ) and i n the same s o i l t r e a t e d w i t h c h l o r a m p h e n i c o l ( • ), c y c l o h e x i m i d e ( Δ ), sodium a z i d e ( 0 ) or gamma i r r a d i a t i o n ( A ).


66


Microbiology,

observations

Head,

Suett

Cain,

ability

to

exogenous samples These

degrade

of

soil

of

Bacterial


nitrogen

source

Wharf

cultures

upon Tyne,

have

Ground

were

able

3,5-dichloroaniline

30

h.

for

their

culture under

when

activity of

thus

was

pH was

confirming

that

cultures,

and a s s o c i a t i o n

degrading

ability

General The of

results

fungicide indicate and

in

has

to

degrading is of

is

both

is

any

above.

and to

degrade

and

above,

proceeded

hydrolysis has

optimum pH

even

is

in

sterile

important

revealed

high

fungicide-degrading with

pesticide

investigation.

agronomic

advantages

in

to

the

good

and p e s t i c i d e s

well-known

for

in

prone

spread

avoid

minimising

stable

more

that

them

so

c a n be

soil

site be

another.

of

successive

encouraged.

the

The v e r y received

possible

In

the

absence

In

either as

in

there

development

of

of

field

iprodione and

it

rotation

addition

rotation,

regular loss

seasons,

such

in

fast

for

degradation

use

single rapid-

bacteria

organism.

from crop

the

to

potential

enhanced

a

soil

have

repeated in

and

clear

target

to

the

may

also

enhanced

Literature Cited

4.

is

of

degradation.

1. 2. 3.

in

soil

The

induced with

of

in

soil

readily.

which

agricultural practices should

degradation

f r o m one

a

the

They

enhanced


the

benefits

site.

concentration

soils

degradation

whenever

are

involvement

indicate

same

to

suggests

initial the

enhanced

same

fungicides

counteract to

the

degrade

some

against

essential

at

iprodione

low

iprodione

at

to

that

common o c c u r r e n c e

also

iprodione

methods

that

a

available

easily

observed of

vinclozolin

important

is

adapt

a very

activity

effective it

not

evidence

of

loss

biological

be

at

ability

applications

crops

h

A t pH 7.5

demonstrate is

dicarboximide

evidence do

clear

degradation

or

50 able

the

plasmids

repeatedly

r a p i d l y degrade

pre-treatment

soils,

described

and

under

of

from

iprodione

not

screening

by

the

absence

5.5,

DNA i n

these

above soils

vinclozolin

other

limited

ability

of

field

been used

that

Some

the

rates

of

currently

summarized

microorganisms

There

Plasmid

with

Conclusions

iprodione

soil.

is

than

chemical

extrachromasomal

the

within

were


conditions.

weight

less

around 6.5.

iprodione

alkaline

molecular

the

The c u l t u r e s

Some reported

isolated

convert

to

fungicides

in

experiments

to

stoichiometrically the

were

cultures

been

vinclozolin

within

U.K.

experiments

(16).

iprodione

from the

enrichment

Newcastle

from these

and Walker

carbon or

degradation


University

preliminary

Audus, L . J . Plant Soil 1949, 2, 31-36. Audus, L . J . Plant Soil 1951, 3, 170-192. Engvild, K.C.; Jensen, H.L. Soil Biol. Biochem. 1969, 1, 295-300. Groves, K.; Chough, K.S. J. Agric. Food Chem. 1979, 18, 1127-1128.


5.

WALKER & WELCH

5. 6. 7. 8. 9. 10.


11. 12. 13. 14. 15. 16.


Roeth, F.W. Reviews of Weed Science 1986, 2, 45-65. Kaufman, D.D. Proc. Br. Crop Prot. Conf.-Weeds 1987, pp. 55-522. Suett, D.L.; Walker, A. Aspects of Applied Biology 1988, 17, 213-222. Entwistle, A.R. Phytopathology 1983, 73, 800. Entwistle, A.R. Aspect of Applied Biology. 1986, 12, 201209. Walker, Α.; Entwistle, A.R.; Dearnaley, N.J. In Soils and Crop Protection Chemicals; Hance, R.J. Ed.; British Crop Protection Council Monograph No. 27; British Crop Protection Council, Croydon, 1984; pp 117-123. Walker, Α.; Brown, P.A.; Entwistle, A.R. Pestic. Sci. 1986, 17, 183-193. Walker, A. Pestic. Sci. 1987a, 21, 219-231. Walker, A. Pestic. Sci. 1987b, 21, 233-240. Cayley, G.R.; Hide, G.A. Pestic. Sci, 1980, 11, 15-19. Racke, K.D.; Coats, J.R. J . Agric. Food Chem. 1987, 35, 9499. Head, I.M.; Cain, R.B.; Suett, D.L.; Walker, A. Proc. Br. Crop. Prot. Conf. - Pests and Diseases 1988, pp. 699-704.

RECEIVED January 22, 1990


67

Enhanced Biodegradation of Pesticides in the Environment - American

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