1. Managing Brome Grass in Mallee
No-till Cropping Systems
Brome Herbicide
Resistance
Update
Tanja Morgan
Acknowledgments
Peter Boutsalis

2. Why Brome is a problem
• Widely distributed
• Increasing under no-till
• Dark requirement
• Delayed germination
• Cold requirement
• Limited in-crop herbicides
• Cereals: Group B
• Broadleaf crops: Group A
Herbicide resistance is developing

3. Brome can survive tough growing conditions…

4. Source: S Kleemann

5. Factors that influence resistance
• Initial frequency of
resistance genes
• The number of
weeds treated
(weed density)
• Selection pressure

6. How Soon Does Resistance Happen? -
Rules of Thumb
Herbicide Group Years to resistance
B- Glean 4
A- Hoegrass 6-8
C- Simazine 10-15
D- Trifluralin 10-15
F- Brodal ~10
L- Sprayseed >12
M- Glyphosate ~15

7. Uni of Adelaide random weed surveys between 2004-2012
(paddock surveyed)
P Boutsalis

8. Testing of survey samples • Seed on soil surface
• Cover with alfoil for 3
weeks at 10°C
• Transplant what
grows (90% +
germination)
• Herbicides applied:
– Atlantis 11/2 leaf stage
– FOPs/ DIMs and
Intervix 3 leaf stage

9. Herbicide resistance – Mallee Region
random surveys
Survey Year Verdict % Select % Atlantis % Crusader % Intervix %
South Australia
N-Mallee 2012 0 0 64 75 0
S-Mallee 2012 0 0 26 24 0
South East 2013 14 0 16 13 0
Atlantis resistant brome also resistant to Crusader and Monza
Source: P Boutsalis

10. Herbicide resistance- random
surveys
Survey Year Verdict
(%)
Select
(%)
Atlantis
(%)
South Australia
Mallee 2007 0 0 33
Mid North 2008 2 0 3
Eyre Peninsula 2009 0 0 5
Victoria
Western 2010 6 7 37
Northern 2011 0 0 0
Source: P Boutsalis

11. SA Mallee survey results 2013
Rating Verdict®
100ml/ha
Select®
500ml/ha
Atlantis®
330ml/ha
Intervix®
600ml/ha
S 14 37 10 38
R 23 2 26 -
RR 2 - 2 -
RRR - - 1 1
Samples
Resistant % 64 5 74 2
• 40 samples collected from northern and southern Mallee
• Targeting brome hot spots - different to random survey
• Matching up herbicide histories to results
Farmer samples - 5 confirmed cases of brome glyphosate resistance in the SA
Mallee

12. Brome grass resistant to Intervix on the left – survived a rate of 1.8L Intervix/ha

13. Results Ratings
RRR
RR
R
P Boutsalis

14. Testing for resistance and
Group A’s & B’s-
how herbicide resistance testing
helps

15. Brome & Barley grass resistance- Group A’s
FOPS DIM
If resistant to
below:
Verdict Targa Select Factor
Verdict - R R ? R ?
Targa R - R ? R ?
Select R ? R ? - R ?
Factor R ? R ? R -
Rate response: get slight rate response (metabolic resistance)
P Boutsalis

16. Brome resistance- Group B’s
Sulfonylureas IMI’s TP’s
If resistant to
below:
Monza Atlantis
Intervix =
OnDuty
Crusader
Monza - R?
?
R?
Atlantis R - ? R?
Intervix R R - R
Crusader R R ? -
P Boutsalis

17. Weed Control
• Knock-down (non-selective)
• Pre-emergent herbicide mixes
– Trifluralin, Metribuzin, Sakura etc.
• Post-emergent herbicides
– Group A: Targa, Verdict, Select- legumes and canola
– Group B: Atlantis, Crusader, Monza- wheat
– Group B: Intervix, Midas- Clearfield wheat, barley, canola
• Crop-topping (non-selective)
• Limited choice of different MoA herbicides
• Increased reliance on herbicides -> resistance
Source – P Boutsalis, University of Adelaide

18. Pre-em herbicides for brome grass
Reductioninbromepanicles
(%)
N
il
T
riflu
ralin
+
M
etrib
u
zin
T
riflu
ralin
+
S
to
m
p
S
aku
ra
S
aku
ra
+
M
etrib
u
zin
S
aku
ra
+
A
vad
ex
0
2 0
4 0
6 0
8 0
1 0 0
Source: P Boutsalis, S Kleemann, G Gill and C Preston, The University of Adelaide

19. Brome grass control at Pira, Vic 2013
Untreated control
Sakura + Avadex Xtra
Source: M Witney (Dodgshun Medlin)

20. Pre-emergent herbicides
Sometimes they work well,
Sometimes you don’t get the result you were
expecting
Depends on:
• Water solubility
• Binding to soil components
• Moisture availability
• Position of weed seed
• Rate of herbicide degradation
in soil

21. Brome germination & pre-ems
• Germination stage of brome can affect
performance of pre-ems
• Trifluralin, Sakura® and metribuzin
• Brome seeds sprayed 0-14 days after sowing
• Most advanced seeds already emerged.
P Boutsalis, G Gill, C Preston – University of Adelaide

22. P Boutsalis
Survival % of B. rigidus with Trifluralin 7 weeks after treatment.
Brome was sprayed at 0 (T-0 [dry seed]), 3 (T-3), 5 (T-5), 7 (T-7), 10 (T-10),
12 (T12) and 14 (T-14 (1-leaf)) days after sowing.
• Trifluralin gave good control of non-germinated brome seed
• Brome control reduced if trifluralin applied after germination
Trif750
Trif1500
Trif3000
0
20
40
60
80
100
Survival(%)
Bromus rigidus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
100
Bromus rigidus
0
20
40
60
80
100
Herbicidedamage(%)
100
)
a b
c d

23. Survival % of B. rigidus with Sakura 7 weeks after treatment.
• Sakura effectively controlled brome at all germination stages but was
less effective on emerged brome.
Trif750
Trif1500
Trif3000
0
20
40
Survi
T-10
T-12
T-14
Sakura
60g/ha
Sakura
120g/ha
Sakura
240g/ha
0
20
40
60
80
100
Survival(%)
Bromus rigidus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
0
20
40
Herbicide
S
0
20
40
60
80
100
Herbicidedamage(%)
c d

24. Survival % of B. rigidus with Metribuzin (WG750) 7 weeks after
treatment.
• A high rate of metribuzin gave effective control
• Control reduced at 150g/ha rate especially on non-germinated brome in
dry soil
• Ideal moisture conditions required for good results
Sakura
60g/ha
Sakura
120g/ha
Sakura
240g/ha
0
20
40
60
Surviva
T-5
T-7
T-10
T-12
T-14
M
etribuzin
75g/ha
M
etribuzin
150g/ha
M
etribuzin
300g/ha
0
20
40
60
80
100
Survival(%)
Bromus rigidus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
0
20
40
60
Herbicideda
M
e
0
20
40
60
80
100
Herbicidedamage(%)
e

25. Improve effectiveness of pre-ems
• Keep weed seeds on soil surface
• Leave stubble standing rather than slashed
• Use herbicide suited to paddock conditions
• Use well calibrated spray equipment
• Use sufficient water rates
X
C Preston

26. Making Intervix last
• Low weed pressure
• Rotate MoA
• Use only one Group B per season
• No more than two (2) Group B herbicides in any four
(4) year period – avoid consecutive years
• Use Intervix with another strategy
In all cases, ensure survivors from any treatment
do not set and shed seed.

27. Intervix® and…
• Knock downs
• Pre-emergent herbicides
• Crop competition
• Patching crop
• Hay cut
• Harvest weed seed
capture

28. Quick-Test
Monitoring:
identify survivors
Why has this individual survived
and the others haven't?
Is it resistant?
Look for similar growth stages

29. Quick-Test: Collect plants
Growth stage = 1-2 leaf to advanced tillering
Green and healthy

30. Resistance test results
Look at concentration of brome in the paddock plus % survival

31. Resistance Testing
• Know your weed enemy
• ‘Don’t choose the wrong herbicide’
• Save money