Efficacy and selectivity
of pre-emergence herbicides
in sunflower as influenced
by soil water conditions
Miroslav Jursík
Jiří Andr
Veronika Venclová
Josef Soukup
E-mail: jursik@af.czu.cz
Typical sunflower weeds in the Czech Republic
Echinochloa crus-galli
Polygonum lapathifolium
Chenopodium album
Amaranthus retroflexus
Locally occurring sunflower weeds
in the Czech Republic
Solanum nigrum
Mercurialis annua
Abutilon Theophrasti
Datura stramonium
Weed control in sunflower in
Czech Republic



90 % of sunflower area is treated by pre-emergence soil
herbicides
sunflower is very sensitive to many herbicides – metabolic
type of selectivity is usually low
intensive precipitation after herbicide application (especially
on sandy soil) may cause vertical movement of herbicide
into the zone with germinating seeds of sunflower and
damage them (phytotoxicity)
Pre-emergence weed control in
sunflower in the Czech Republic
widely used tank-mix combinations
of herbicides
linuron
prosulfocarb
oxyfluorfen
 pendimethalin
flurochloridone
bifenox
dicot weeds
acetochlor
+
alachlor
dimethenamid
metolachlor
grass weeds
Material and methods
Trial layout
tested herbicides:
Active ingredience
Goal 2 E
oxyfluorfen
Herb. rate
(l.ha-1)
1,00
Afalon 45 SC
linuron
1,50
Racer 25 EC
flurochloridone
3,00
Stomp 400 SC
pendimethalin
4,00
Boxer
prosulfocarb
5,00
Trophy
acetochlor
2,50
Herbcide
Half of each plot was irrigated
by simulation of 30 mm precipitations
(2-3 weeks after herbicide application)
Material and methods
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experimental years: 2008 and 2009
soil characteristic: chernozem, clay
content 46 %, soil pH (KCl) 7.5, sorption
capacity of soil: 209 mmol(+), 87 ppm P,
203 ppm K, 197 ppm Mg, 8073 ppm Ca
occurring weeds: Echinochloa crus-galli,
Amaranthus retroflexus, Chenopodium
album and Mercurialis annua
Materials and methods
Soil moisture conditions:
dry condition –
natural precipitation – 25 mm
within 4 WAT
wet condition –
intensive natural
precipitation (65 mm within 4 WAT)
simulated rainfall –
(natural precipitation
25 mm within 4 WAT + 30 mm irrigation)
Efficacy of tested herbicides on
Amaranthus retroflexus
under different rainfall conditions
dry condition
simulated rainfall
wet condition
acetochlor
prosulfocarb
low efficacy in dry condition
pendimethalin
fluorochloridone
low efficacy in dry condition
linuron
oxyfluorfen
0
10
20
30
40
50
60
70
80
90
100
efficacy (%)
Efficacy of tested herbicides on
Chenopodium album
under different rainfall conditions
dry condition
simulated rainfall
wet condition
acetochlor
prosulfocarb
efficacy was not influenced by rainfall
pendimethalin
fluorochloridone
linuron
oxyfluorfen
0
10
20
30
40
50
60
70
80
90
100
efficacy (%)
Efficacy of tested herbicides on
Echinochloa crus-galli
under different rainfall conditions
dry condition
simulated rainfall
wet condition
efficacy was not influenced by rainfall
acetochlor
prosulfocarb
efficacy was not influenced by rainfall
pendimethalin
fluorochloridone
linuron
oxyfluorfen
0
10
20
30
40
50
60
70
80
90
100
efficacy (%)
Efficacy of tested herbicides on
Mercurialis annua
in different dry condition
dry condition
simulated rainfall
wet condition
acetochlor
prosulfocarb
pendimethalin
fluorochloridone
linuron
efficacy was not influenced by soil moisture
oxyfluorfen
0
10
20
30
40
50
60
70
80
90
100
efficacy (%)
Selectivity of tested herbicides to
sunflower in different dry condition
4 week after application
dry condition
simulated rainfall
wet condition
acetochlor
prosulfocarb
no phytotoxicity in all tested
rainfall conditions
pendimethalin
fluorochloridone
linuron
phytotoxicity influenced by size of rain drops
oxyfluorfen
0
5
10
15
20
25
30
35
40
45
50
efficacy (%)
Conclusions
acetochlor
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excellent and long-term residual efficacy
on E. crus-galli and A. retroflexus
efficacy was not affected by rainfall
Conclusions
acetochlor
Chenopodium album
wet conditions
Mercurialis annua
dry conditions
Conclusions
acetochlor
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excellent and long-term residual efficacy
to E. crus-galli and A. retroflexus
efficacy was not affected by soil moisture
slow metabolism by sunflower - risk if
used on sandy soil
sunflower injury is often hidden and
cause a grow retardation
Conclusions
oxyfluorfen

excellent efficacy on A. retroflexus and
very good efficacy on M. annua – not
very influenced by rainfall
Conclusions
oxyfluorfen
E. crus-galli
Chenopodium album
wet conditions only in dry conditions
Conclusions
oxyfluorfen
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excellent efficacy on A. retroflexus and
very good efficacy on M. annua – not very
influenced by rainfall conditions
short residual activity
slow metabolism by sunflower –
phytotoxicity was caused by rain drops
which reflected from soil surface –
necrosis and deformation of leaves
Conclusions
linuron
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good efficacy on all tested weeds, but
only in wet conditions
very low efficacy in dry conditions
Conclusion
linuron
wet condition
dry condition
Conclusion
linuron
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good efficacy on all tested weeds, but
only in wet conditions
low efficacy in dry conditions
relative short residual activity (up to 2
months after application) – fast
development of sunflower leaf coverage
is necessary
high selectivity to sunflower – possibility
of use on sandy soils
Conclusion
flurochloridone
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Lower selectivity to sunflower – risk if used
on sandy soils
phytotoxicity symptom on sunflower is
bleaching
excellent efficacy on all tested weeds, but
only in wet conditions
reduced efficacy mainly on E. crus-galli and
M. annua in dry conditions
long-term residual activity
Conclusion
flurochloridone
wet conditions
dry conditions
Conclusions
prosulfocarb
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excellent efficacy on all tested weeds, but
only in wet conditions
in dry soil conditions, good efficacy was
found only on A. retroflexus
Conclusion
prosulfocarb
wet condition
dry condition
Conclusions
prosulfocarb
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excellent efficacy on all tested weeds, but
only in wet conditions
in dry conditions good efficacy only on A.
retroflexus was found
relative short residual activity
high selectivity to sunflower – possibility of
use on sandy soils
Conclusions
pendimethalin
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excellent and long-term efficacy on C.
album in all tested wet conditions
for other assessed weeds - short residual
activity and efficacy is partially influenced
by soil water conditions
Conclusion
pendimethalin
wet conditions
dry conditions
Conclusion
pendimethalin
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excellent and long-term efficacy on C.
album in all tested conditions
for other tested weeds - short residual
activity and efficacy is partially influenced
by soil watter conditions
breaking and lodging of stems may occurr
as a result of callus creation on stem base
Thank you for your attention