J Orson

Roundup Ready Maize symposium: The European Perspective

Current and future role of the

non-selective use of glyphosate

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non-selective use of glyphosate

Jim Orson


“All our attempts at couch control by cultivation have been fruitless.”

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Andrew Charlton, Farmer’s Weekly

January 2009


Glyphosate

• 1974 - introduced in UK for perennial weed control

• 1980 - pre-harvest application introduced

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Reduction (%) of common couch shoots in the following

season after pre-harvest or post-harvest application of

a range of doses (kg ae/ha) of glyphosate in 1979 in

Scotland (Source; O’Keeffe et al., 1981)

Site Pre-harvest Post-harvest

0.72 1.44 0.72 1.44

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0.72 1.44 0.72 1.44

1 99.7 99.7 95.1 97.8

2 98.8 98.4 64.5 89.6

3 99.4 99.2 31.6 93.7

4 - 90.0 - 60.0


Glyphosate – a few properties

Solubility in water (20oC) = 10,500 mg/l

Koc = non-mobile

GUS leaching potential index = -0.36

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GUS leaching potential index = -0.36

Potential for particulate bound transport = medium


UK competitiveness based on technology Average wheat yields (t/ha)

6

7

8

9t/ha

Effectiveherbicides

Effectivefungicides

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0

1

2

3

4

5

6

1968

1973

1978

1983

1988

1993

1998

2003

2008

Semi-dwarfvarieties

Increase in N


% of winter wheat in England established

after non-plough tillage

30

35

40

45

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0

5

10

15

20

25

30

1975

1976

1977

1978

1979

1980

1981

1982

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

Source:


40

50

60

Cro

ps d

rille

d (

%)

September

Before 20/09

% of winter wheat crops in England sown in September and

before 20th September, 1970-2008 harvest years

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0

10

20

30

1970

1972

1974

1976

1978

1980

1982

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

Cro

ps d

rille

d (

%)

Source:


Glyphosate

• Introduced in UK for perennial weed control in 1974

• Pre-harvest application introduced in 1980

And then it got cheaper!

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And then it got cheaper!

• Subsequently used for annual grass and broad-leaved weed control and crop dessication

• Glyphosate residues commonly occur in UK bread (below MRLs)


Percentage of bread samples (ordinary and speciality)

containing glyphosate residues, 2000-2006

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Wheat yield (t/ha @ 85% MC) and moisture content (%) of grain at harvest of Consort wheat, treated or not treated with 1.0 l/ha Roundup (360 g ae/l glyphosate) when the bulk grain content of the site was 30% moisture content; Morley 1999

Fungicide programme 1.0 l/ha

Roundup

Yield

(t/ha)

% moisture

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No No 6.52 18.23

No Yes 6.32 14.96

Non-strob No 7.31 17.34

Non-strob Yes 6.81 14.91

Strob No 8.44 17.01

Strob Yes 7.68 15.45


Wheat yield (t/ha @ 85% MC) and moisture content (%) of grain at harvest of Consort wheat, treated or not treated with 1.0 l/ha Roundup (360 g ae/l glyphosate) when the bulk grain content of the site was 30% moisture content; Morley 1999

Fungicide programme 1.0 l/ha

Roundup

Yield

(t/ha)

% moisture

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No No 6.52 18.23

No Yes 6.32 14.96

Non-strob No 7.31 17.34

Non-strob Yes 6.81 14.91

Strob No 8.44 17.01

Strob Yes 7.68 15.45

No impact on

qualityin clean crops

MOG


% of winter wheat in England established

after non-plough tillage

30

35

40

45

The value of stale

seedbeds?

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0

5

10

15

20

25

30

1975

1976

1977

1978

1979

1980

1981

1982

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

Source:

seedbeds?

CerealsRye-grass

Barren bromeMeadow brome -

NoBlack-grass?Wild-oats?

Seeds can be lost without creating plants


Post-drilling use

• Convenience – rather than improved weed control

• Maize in France:– up to 48 hours after drilling provided soil has more

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– up to 48 hours after drilling provided soil has more than 10% clay (<24 hours and max dose of less than 360 g ae/ha if soil is sandy)

– soil well structured and seed well covered


Most likely active substances to fail re-registration as

a result of the revision of 91/414

• 2,4-D? (2011)• Amitrole?? (2011)

• Carbendazim (2009)*• Carbetamide? (2020)

• Chlorotoluron? (2016)

• Cyproconazole?? (2020)

• Metribuzin? (2017)• Pendimethalin (2013)*

• Picloram? (2018)• Prochloraz? (2020)

• Prothioconazole? (2018)• Quinoxyfen (2014)*

• Tebuconazole?? (2018)

• Flumioxazine (2012)

• Fluquinconazole? (2020)

• Flusilazole (not sure)

• Glufosinate (2017)

• Ioxynil?? (2015)

• Ipridione?? (2013)

plus

Water

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(2020)• Deltamethrin? (2013)

• Dimethoate? (2016)

• Dinocap (2009)• Epoxiconazole??

(2018)

• Esfenvalerate (2011)*

• Tebuconazole?? (2018)• Tepraloxydim? (2015)

• Thiram? (2013)

• Triflusulfuron? (2018)

* = no derogation

Other active substances may be subject to candidates for substitution– particularly most insecticides

• Ipridione?? (2013)

• Linuron (2013)

• Mancozeb?? (2016)

• Maneb?? (2016)

• Metconazole?? (2017)

? = endocrine disruptor on PSD assessment

?? = endocrine disruptor on both PSD and Swedish assessment

Water Framework

Directive


% reduction in black-grass heads from the application of 2,500 g/ha isoproturon at GS 11-13 of the weed – individual

TAG trials 1996-2007 (blue) and average (green)

60

70

80

90

100

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0

10

20

30

40

50

60

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007


% reduction in black-grass heads from the application of 2.5 l/ha Hawk at GS 11-13 of the weed – individual TAG trials

1996 – 2004 (blue) and average (green)

60

70

80

90

100

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0

10

20

30

40

50

60

1996

1997

1998

1999

2000

2001

2002

2003

2004

No. trials 3 4 5 6 8 8 9 6 3


Cases of resistance to ‘Atlantis’

(mesosulfuron+iodosulfuron) in

black-grass in the UK by 2008(‘Atlantis’ introduced autumn 2003)

• >250 cases confirmed in pot tests

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• >250 cases confirmed in pot tests

• In 21 counties• Most not ‘field failures’

• Target site resistance (Pro197) confirmed on 10

farms• Target site resistance (Trp574) confirmed on 1 farm

• Both target site mutations

(Pro197 & Trp574 ) on 1 farm• Enhanced metabolism also probable

• 79% also ACCase (‘fop’/‘dim’) TSR

Compilation of Bayer, Syngenta and Rothamsted results


The future – do we need a Plan B?

• Need to embrace new technologies (e.g. remote sensing and GM) in addition to refining current technologies to reduce dose/ha of key active substances

• Need to build up fertility in soils in order to:

– sustain/increase yields

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– sustain/increase yields

– increase flexibility of cropping

J Orson

Technology

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