Efficacy and flexibility of Roundup Ready® maize production systems – an European example

1. Brussels
22-24 March 2010
Efficacy and flexibility of Roundup Ready®
maize production systems
– an European example
Josef Soukup
M. Jursík, V. Venclová, J. Holec, M. Laksarová
Jursík, Holec,
Czech University of Life Sciences Prague
soukup@af.czu.cz
soukup@af.czu.cz

2. Main points of the talk:
talk:
Main issues of the weed ecology and
weed control in maize
Characteristics and limitation of
current usage of herbicides in maize
Experience with RR maize NK 603
with tolerance to glyphosate
Conclusions

3. „Big four“ - crops ensuring
four“
80 % of world´s caloric consumption
world´
Crop Acrage Production
(x1000 ha) (x1000 t)
wheat 217.433 607.045
maize 157.874 784.786
rice 156.952 651.743
soybean 94.899 216.144
2007
In Europe, maize is grown on 13 Mio hectares under
diverse natural environments and farming practices

4. Climatic zones in Europe
EPPO guideline PP 1/241 (1)
Various situations in weed occurrence
exist which require efficient and flexible
weed control systems ...
http://printable-maps.blogspot.com/2008/09/map-of-
climate-zones-in-europe.html

5. New zonal system proposed for
regulation of Plant Protection Products
Proposed zones do not reflect situation in:
- temperatures, evaporation, winter hardiness
- different farming practices
- weed occurrence and diversity
- specific life cycles in various environments
Registration process will be simplified but....
- use of herbicides should allow local flexibility
- solutions for local conditions have to be developed

6. Differences in registered use of herbicides
in maize in various European regions
Dossage of herbicides:
Herbicide West / Central Europe South Europe, Pannon
Terbuthylazine 750 (max. 1000) g/ha >1200 g/ha
Isoxaflutole 75 – 100 g/ha pre >100 g/ha; pre, post
Mesotrione 100 g/ha >130 g/ha
Solution of specific situations is necessary:
- Ambrosia spp., Sorghum halapense, Panicum spp., ...
Conventional control systems have some gaps so that the
introduction of Roundup Ready system ® could improve
current situation

7. Most frequent weeds in maize:
the group of „late summer annuals“
Echinochloa crus-galli
Polygonum lapathifolium
Chenopodium album Amaranthus retroflexus

8. Most frequent „European“ weeds
European“
in maize
Annuals
Occurring accross Europe
Chenopodium album, Polygonum spp., spp.,
Amaranthus retroflexus, Matricaria spp.,
retroflexus, spp.,
Echinochloa crus-galli, ....
crus-galli,
In southern countries
Ambrosia artemisifolia, Datura
artemisifolia,
stramonium,
stramonium, Conyza canadensis,
canadensis,
Setaria spp., Digitaria sanquinalis, ....
spp., sanquinalis,

9. Annual thermophillic weeds
of local importance
Solanum nigrum Abutilon Theophrasti
Datura stramonium
Ambrosia artemisifolia

10. Invasive annual species in Europe
Panicum spp.
Abutilon Theophrasti
Helianthus annuus

11. Perennial weeds in Central Europe
Agropyron repens
Convolvulus arvensis
Cirsium arvense

12. Most important „European“ weeds in maize
European“
Perennial weeds
Occurring across Europe
Cirsium arvense, Convolvulus arvensis
arvense,
In moderate / colder climate
Agropyron (Elymus) repens,
Elymus) repens,
Bolboschoenus (Scirpus) spp., ....
Scirpus) spp.,
In southern countries
Sorghum halapense, Cyperus spp.,
halapense, spp.,
Cynodon dactylon, ....
dactylon,

13. Emergence of summer annual weeds (CZ)
450,0
Driving factors:
400,0
- temperatures
A. retroflexus - soil moisture
350,0
p o č e No. of emerged tlin (m 2 )
- seed dormancy
t v ze š lý c h ro s plants
300,0 - photoperiodism
- soil tillage
250,0 E. crus-galli - ...
200,0
Ch. album
150,0
S. nigrum
M. annua
100,0
50,0
D. stramonium
0,0
3
4
5
6
7
.7
.8
.9
0
1
3.
2.
2.
1.
1.
.1
.1
31
30
29
29
28
3-4 months weed emergence
Jursík et al. 2007, adapted

14. Critical period in maize:
„proper time for exclusion of weed competition“
relative yield [%]
100
weeds occurr until ...
80 weeds occurr from ...
60
4 . – 8. maize leaves
40
20
critical period
0
time (maize growth stage)

15. Timing of herbicide application in maize
according to crop and weed emergence
Weed emergence (plants/m2)
6 maize leaves
(
HT varieties
post- em
Maize sowing
pre-em herbicides (6-8 weeks of activity)
Data on ECHCG emergence from Jursík 2004

16. General requirements on herbicides:
herbicides:
High efficacy (> 95%) and wide
spectrum of weed species controlled
Crop safety (< 5 % injury, disapearing)
injury, disapearing)
Safety for subsequent crops in rotation
Low hectare costs
Flexible timing of application

17. What herbicides are available
(...and which of them will be registered in the
(...and
future after revision proces of PPP?)
http://ec.europa.eu/food/plant/protection/evaluation/rev_
prog_exist_pest_en.htm

18. Main pre-emergence herbicides
(main used modes of action)
PS II inhibitors (C)
atrazine
terbuthylazine
linuron
VLCFA, mitose, and cell division inhibitors (K)
acetochlor
S-metolachlor
pendimethalin
Inhibitors of plant pigments syntheses (F)
isoxaflutole
sulcotrione,
sulcotrione, mesotrione

19. Main post-emergence herbicides
post-
PS II inhibitors (C)
terbuthylazine
bromoxynil
ALS nhibitors (B)
sulfonylureas (nicosulfuron, thifensulfuron,
nicosulfuron, thifensulfuron,
foramsulfuron, iodosulfuron,,
foramsulfuron, iodosulfuron,, ...)
triazolopyrimidines (florasulam)
florasulam)
Synthetic auxins (O)
dicamba,
dicamba, 2,4 D, fluroxypyr, clopyralid, ...
fluroxypyr, clopyralid,
Inhibitors of plant pigments syntheses (F)
mesotrione, sulcotrione,
mesotrione, sulcotrione, tembotrione

20. Trends of herbicide resistance for
individual mode of actions

21. Crop injury caused by herbicides
bromoxynil Slight crop injury (phytotoxicity)
5-15% is very common for many
post-emergence herbicides
2,4 D
rimsulfuron

22. Risk of residual effect of soil active
herbicides on subsequent crops
Damage in subsequent barley in crop rotation
after small plot trial with maize herbicides

23. Possible use of Roundup Ready®
System in various weediness situations
Application of Roundup stand alone (split)
standard conditions, perennial weeds
conditions,
Split application: pre-emergence herbicide
application: pre-
followed by Roundup
dry conditions, high weed densities
conditions,
Post-
Post-emergence „tank-mix“ application of
„tank-
residual herbicide with Roundup Ready®
control of late emerging species
Split application with various POST herbicides
against weeds hardly controlled by glyphosate

24. Suitable combination products
Recommended by Monsanto in USA:
Harness (acetochlor)
acetochlor)
Harness Xtra, Keystone (acetochlor +
Xtra,
atrazine)
atrazine)
Bicep II Magnum (S-metolachlor + atrazine)
(S- atrazine)
Suitable combination products meeting
the European registration rules:
rules:
S-metolachlor, acetochlor
metolachlor,
terbuthylazine (+acetochlor)
(+acetochlor)
isoxaflutole – only for pre-em application
pre-
mesotrione – expensive, low residual effect
expensive,

25. 3 years experience from field
trials in CZ
Comparison of 4 selected variants:
variants:
1) Conventional pre-emergence control
pre-
(isoxaflutole + acetochlor)
acetochlor)
2) Conventional post-emergence herbicide
post-
(foramsulfuron + iodosulfuron + isoxadifen ethyl)
ethyl)
3) Split application of Roundup Ready®
(1080 g/ha glyphosate twice)
twice)
4) Tank-mix Roundup Ready® + soil residual
Tank-
(1080 g/ha glyphosate + acetochlor)
acetochlor)

26. Weed occurrence and density
Plot before application Untreated plot
16.6.2009 13.7.2009

27. Conventional pre-emergence control
pre-
(isoxaflutole + acetochlor)
acetochlor)
6 WAT 10 WAT
Weed-free plot already from the beginning of vegetation
Weed escapes of hard-to-control species (MERAN, ECHCG)
Efficacy varied between years in dependence on soil moisture

28. Conventional post-emergence herbicide
post-
(foramsulfuron + iodosulfuron)
iodosulfuron)
2 WAT 5 WAT
Slower but strong herbicide effect
Slight crop injury – yellowing of leaves for 2 weeks
Excellent control effect, sometimes few surviving plants (MERAN)

29. Split application of Roundup Ready®
(1080 g/ha glyphosate twice)
twice)
2 WAT 5 WAT
Fast herbicide effect
Repeated application of glyphosate ensure control of survivals
Best effect from viewpoint of efficacy and species equitability

30. Tank-mix Roundup Ready® + soil residual
Tank-
(1080 g/ha glyphosate + acetochlor)
acetochlor)
3 WAT 6 WAT
Best herbicide effect in some years but not in all
Effect depends on right timing and soil moisture conditions
Sometimes escaped plants of ECHCG and MERAN

31. Different species sensitivity (WAT4)
Weed Picture Curv ED50 ED90 ED90 / ED50
ratio
AMARE 197.1 411.9 2.1
AMARE
SOLPS 265.4 475.0 1.8
CHEAL 363.6 677.1 1.9
MERAN 249.1 685.4 2.8
ECHCG
ECHCG 361.7 1334.6 3.7

32. Efficacy (%) on selected weed species
(varying among 3-years of experiements)
experiements)
CHEAL AMARE ECHCG MERAN
Conventional 90-100 100 85-98 65-85
pre-em
Conventional 96-100 99-100 96-100 90-95
post-em
Roundup 99-100 100 98-100 95-98
split appl.
Roundup + 97-100 100 90-98 80-90
acetochlor
Control best very good weed
reliability escapes

33. Summary – efficacy, selectivity
efficacy,
Both RR treatments (split; with acetochlor)
acetochlor)
show very good/excellent efficacy
good/
Very good selectivity also in combination with
acetochlor applied post-emergence
post-
Different results for RR split vs.
RR+acetochlor
RR+acetochlor were found in individual years
Under dry weather conditions (2007) - strong
competition for water already in BBCH 14!14!
Second weed flush was not an important
issue in any of experimental years

34. Summary – weed diversity
Reasons for weed shift were not noticed when
glyphosate was applied at recommended doses
Weed escapes occurred mostly when soil
active herbicides were used
Best parameters of species richness and
eveness were noticed when glyphosate was
applied stand alone
Post-em. application of glyphosate allowed
weeds to realise their beneficial functions

35. Conclusions:
RR System seems to be an effective tool for weed
control in maize also in Europe
similar or better efficacy than conventional herbicides
better reliability, selectivity and timing flexibility
negative effects on weed community were not noticed
Glyphosate has specific features (like other
herbicides) which must be taken into account
no residual activity (right timing, split appl. combinations, …)
differences in species sensitivity (dossage according to
most tolerant species or with combination partners)