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Managing Brome Grass in Mallee
No-till Cropping Systems
Brome Herbicide
Resistance
Update
Tanja Morgan
Acknowledgments
Pet...
Why Brome is a problem
• Widely distributed
• Increasing under no-till
• Dark requirement
• Delayed germination
• Cold req...
Brome can survive tough growing conditions…
Source: S Kleemann
Factors that influence resistance
• Initial frequency of
resistance genes
• The number of
weeds treated
(weed density)
• S...
How Soon Does Resistance Happen? -
Rules of Thumb
Herbicide Group Years to resistance
B- Glean 4
A- Hoegrass 6-8
C- Simazi...
Uni of Adelaide random weed surveys between 2004-2012
(paddock surveyed)
P Boutsalis
Testing of survey samples • Seed on soil surface
• Cover with alfoil for 3
weeks at 10°C
• Transplant what
grows (90% +
ge...
Herbicide resistance – Mallee Region
random surveys
Survey Year Verdict % Select % Atlantis % Crusader % Intervix %
South ...
Herbicide resistance- random
surveys
Survey Year Verdict
(%)
Select
(%)
Atlantis
(%)
South Australia
Mallee 2007 0 0 33
Mi...
SA Mallee survey results 2013
Rating Verdict®
100ml/ha
Select®
500ml/ha
Atlantis®
330ml/ha
Intervix®
600ml/ha
S 14 37 10 3...
Brome grass resistant to Intervix on the left – survived a rate of 1.8L Intervix/ha
Results Ratings
RRR
RR
R
P Boutsalis
Testing for resistance and
Group A’s & B’s-
how herbicide resistance testing
helps
Brome & Barley grass resistance- Group A’s
FOPS DIM
If resistant to
below:
Verdict Targa Select Factor
Verdict - R R ? R ?...
Brome resistance- Group B’s
Sulfonylureas IMI’s TP’s
If resistant to
below:
Monza Atlantis
Intervix =
OnDuty
Crusader
Monz...
Weed Control
• Knock-down (non-selective)
• Pre-emergent herbicide mixes
– Trifluralin, Metribuzin, Sakura etc.
• Post-eme...
Pre-em herbicides for brome grass
Reductioninbromepanicles
(%)
N
il
T
riflu
ralin
+
M
etrib
u
zin
T
riflu
ralin
+
S
to
m
p...
Brome grass control at Pira, Vic 2013
Untreated control
Sakura + Avadex Xtra
Source: M Witney (Dodgshun Medlin)
Pre-emergent herbicides
Sometimes they work well,
Sometimes you don’t get the result you were
expecting
Depends on:
• Wate...
Brome germination & pre-ems
• Germination stage of brome can affect
performance of pre-ems
• Trifluralin, Sakura® and metr...
P Boutsalis
Survival % of B. rigidus with Trifluralin 7 weeks after treatment.
Brome was sprayed at 0 (T-0 [dry seed]), 3 ...
Survival % of B. rigidus with Sakura 7 weeks after treatment.
• Sakura effectively controlled brome at all germination sta...
Survival % of B. rigidus with Metribuzin (WG750) 7 weeks after
treatment.
• A high rate of metribuzin gave effective contr...
Improve effectiveness of pre-ems
• Keep weed seeds on soil surface
• Leave stubble standing rather than slashed
• Use herb...
Making Intervix last
• Low weed pressure
• Rotate MoA
• Use only one Group B per season
• No more than two (2) Group B her...
Intervix® and…
• Knock downs
• Pre-emergent herbicides
• Crop competition
• Patching crop
• Hay cut
• Harvest weed seed
ca...
Quick-Test
Monitoring:
identify survivors
Why has this individual survived
and the others haven't?
Is it resistant?
Look f...
Quick-Test: Collect plants
Growth stage = 1-2 leaf to advanced tillering
Green and healthy
Resistance test results
Look at concentration of brome in the paddock plus % survival
Resistance Testing
• Know your weed enemy
• ‘Don’t choose the wrong herbicide’
• Save money
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Brome Herbicide Resistance Update - Tanja Morgan

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Brome Herbicide Resistance Update - Tanja Morgan

  1. 1. Managing Brome Grass in Mallee No-till Cropping Systems Brome Herbicide Resistance Update Tanja Morgan Acknowledgments Peter Boutsalis
  2. 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. 3. Brome can survive tough growing conditions…
  4. 4. Source: S Kleemann
  5. 5. Factors that influence resistance • Initial frequency of resistance genes • The number of weeds treated (weed density) • Selection pressure
  6. 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. 7. Uni of Adelaide random weed surveys between 2004-2012 (paddock surveyed) P Boutsalis
  8. 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. 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. 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. 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. 12. Brome grass resistant to Intervix on the left – survived a rate of 1.8L Intervix/ha
  13. 13. Results Ratings RRR RR R P Boutsalis
  14. 14. Testing for resistance and Group A’s & B’s- how herbicide resistance testing helps
  15. 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. 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. 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. 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. 19. Brome grass control at Pira, Vic 2013 Untreated control Sakura + Avadex Xtra Source: M Witney (Dodgshun Medlin)
  20. 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. 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. 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. 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. 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. 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. 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. 27. Intervix® and… • Knock downs • Pre-emergent herbicides • Crop competition • Patching crop • Hay cut • Harvest weed seed capture
  28. 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. 29. Quick-Test: Collect plants Growth stage = 1-2 leaf to advanced tillering Green and healthy
  30. 30. Resistance test results Look at concentration of brome in the paddock plus % survival
  31. 31. Resistance Testing • Know your weed enemy • ‘Don’t choose the wrong herbicide’ • Save money

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