This document discusses the use of glyphosate in Europe, specifically the UK. It provides background on glyphosate, noting its introduction in 1974 for perennial weed control and pre-harvest use in 1980. Data is presented on glyphosate's effectiveness in reducing common couch shoots. The document also discusses glyphosate residues in UK bread and impacts on wheat yield and moisture content from pre-harvest glyphosate applications.

1. Roundup Ready Maize symposium: The European Perspective
Current and future role of the
non-selective use of glyphosate
Jim Orson
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2. Roundup Ready Maize symposium: The European Perspective
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3. Roundup Ready Maize symposium: The European Perspective
“All our attempts at couch control by
cultivation have been fruitless.”
Andrew Charlton, Farmer’s Weekly
January 2009
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4. Roundup Ready Maize symposium: The European Perspective
Glyphosate
• 1974 - introduced in UK for perennial weed control
• 1980 - pre-harvest application introduced
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5. Roundup Ready Maize symposium: The European Perspective
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
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
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6. Roundup Ready Maize symposium: The European Perspective
Glyphosate – a few properties
Solubility in water (20oC) = 10,500 mg/l
Koc = non-mobile
GUS leaching potential index = -0.36
Potential for particulate bound transport = medium
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7. Roundup Ready Maize symposium: The European Perspective
UK competitiveness based on technology
Average wheat yields (t/ha)
t/ha Effective
9
Effective fungicides
8
herbicides
7
6
5 Increase in N
4
3
2
Semi-dwarf
1
varieties
0
68
73
78
83
88
93
98
03
08
19
19
19
19
19
19
19
20
20
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8. Roundup Ready Maize symposium: The European Perspective
% of winter wheat in England established
after non-plough tillage
45
40
35
30
25
20
15
10
5
0
19 5
19 6
19 7
19 8
19 9
19 0
19 1
19 2
19 5
19 6
19 7
19 8
19 9
19 0
19 1
19 2
19 3
19 4
19 5
19 6
19 7
19 8
20 9
20 0
20 1
20 2
20 3
20 4
20 5
20 6
20 7
08
7
7
7
7
7
8
8
8
8
8
8
8
8
9
9
9
9
9
9
9
9
9
9
0
0
0
0
0
0
0
0
19
Source:
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9. Roundup Ready Maize symposium: The European Perspective
% of winter wheat crops in England sown in September and
before 20th September, 1970-2008 harvest years
60
50 September
Before 20/09
Crops drilled (%)
40
30
20
10
0
70
72
74
76
78
80
82
86
88
90
92
94
96
98
00
02
04
06
08
19
19
19
19
19
19
19
19
19
19
19
19
19
19
20
20
20
20
20
Source:
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10. Roundup Ready Maize symposium: The European Perspective
Glyphosate
• Introduced in UK for perennial weed control in
1974
• Pre-harvest application introduced in 1980
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)
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11. Roundup Ready Maize symposium: The European Perspective
Percentage of bread samples (ordinary and speciality)
containing glyphosate residues, 2000-2006
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12. Roundup Ready Maize symposium: The European Perspective
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 Yield % moisture
Roundup (t/ha)
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
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13. Roundup Ready Maize symposium: The European Perspective
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 Yield % moisture
Roundup (t/ha)
No No No 6.52 18.23
No Yes impact6.32
on 14.96
Non-strob MOG No quality
7.31 17.34
Non-strob Yes in clean
6.81 14.91
Strob No crops8.44 17.01
Strob Yes 7.68 15.45
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14. Roundup Ready Maize symposium: The European Perspective
% of winter wheat in England established
after non-plough tillage
45
40 The value
35 of stale
30 seedbeds?
25
20
Cereals
15 Rye-grass
10 Barren brome
5 Meadow brome - Seeds can
0 No be lost
Black-grass? without
19 5
19 6
19 7
19 8
19 9
19 0
19 1
19 2
19 5
19 6
19 7
19 8
19 9
19 0
19 1
19 2
19 3
19 4
19 5
19 6
19 7
19 8
20 9
20 0
20 1
20 2
20 3
20 4
20 5
20 6
20 7
08
7
7
7
7
7
8
8
8
8
8
8
8
8
9
9
9
9
9
9
9
9
9
9
0
0
0
0
0
0
0
0
19
Wild-oats? creating
Source:
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15. Roundup Ready Maize symposium: The European Perspective
Post-drilling use
• Convenience – rather than improved weed
control
• Maize in France:
– 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
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16. Roundup Ready Maize symposium: The European Perspective
Most likely active substances to fail re-registration as
a result of the revision of 91/414
• 2,4-D? (2011) • Flumioxazine (2012) • Metribuzin? (2017)
• Amitrole?? (2011) • Fluquinconazole? (2020) • Pendimethalin (2013)*
• Carbendazim (2009)* • Flusilazole (not sure) • Picloram? (2018)
•
•
Carbetamide? (2020)
Chlorotoluron? (2016)
• plus
Glufosinate (2017) • Prochloraz? (2020)
• Prothioconazole? (2018)
• Ioxynil?? (2015)
• Cyproconazole??
(2020) •
Water
Ipridione?? (2013)
• Quinoxyfen (2014)*
• Tebuconazole?? (2018)
•
•
Deltamethrin? (2013)
Dimethoate? (2016)
• Framework
Linuron (2013) • Tepraloxydim? (2015)
• Thiram? (2013)
• Mancozeb?? (2016)
•
•
Dinocap (2009)
Epoxiconazole??
• Directive
Maneb?? (2016) • Triflusulfuron? (2018)
(2018) • Metconazole?? (2017)
* = no derogation
• Esfenvalerate (2011)*
? = endocrine disruptor on PSD assessment
?? = endocrine disruptor on both PSD and Swedish assessment
Other active substances may be subject to candidates for substitution
– particularly most insecticides
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17. Roundup Ready Maize symposium: The European Perspective
% 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)
100
90
80
70
60
50
40
30
20
10
0
19
19
19
19
20
20
20
20
20
20
20
20
96
97
98
99
00
01
02
03
04
05
06
07
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18. Roundup Ready Maize symposium: The European Perspective
% 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)
100
90
80
70
60
50
40
30
20
10
0
19
19
19
19
20
20
20
20
20
96
97
98
99
00
01
02
03
04
No. trials text 3
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4 5 6 8 8 9 6 3

19. Roundup Ready Maize symposium: The European Perspective
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
• 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
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Compilation of Bayer, Syngenta and Rothamsted results

20. Roundup Ready Maize symposium: The European Perspective
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
– increase flexibility of cropping
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21. Roundup Ready Maize symposium: The European Perspective
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22. Roundup Ready Maize symposium: The European Perspective
Glyphosate
35 years on and still developing new
uses and approaches
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