2015 vic- berriwillock-landmark-resistance-march

1. Herbicide resistance in western Victoria
Dr Peter Boutsalis,
University of Adelaide & Plant Science Consulting
Plant Science
Consulting

2. Why does herbicide resistance occur?
 Herbicides don’t cause resistance!!
 Resistance is naturally present.
 Herbicides select and enrich resistance
 poor spray conditions= low rate= weak resistance
mechanisms stack
 Ryegrass/ wild radish- obligate outcrossing so
combine weak resistance  strong resistance

3. Incidence of
Herbicide resistance

4. Herbicide Resistance Surveys
 Sampling
– End of season
– Collect seed from paddocks
randomly over a wide
geographic area
– Frequency 5-10 km
 Evaluation- Pot testing
– Pot testing in winter
 Resistance levels change so
need to revisit (eg 5 yr interval)

5. Uni of Adelaide random weed surveys between 2004-2014
(paddock surveyed)

6. Testing of survey samples

7. Ryegrass

8. Ryegrass resistance in West-Victoria
Western Victoria
Results of weed survey of 125 paddocks chosen at random in 2005 & 2010 conducted by the University of
Adelaide. Paddocks were scored as resistant if the seeds collected exhibited >20% survival in a pot test
conducted the following winter. Thus samples that exhibited 1% to less than 20% survival were scored as non-
resistant.
Region Year Trifluralin Hoegrass Glean Intervix Achieve Axial Select
VICTORIA
Western 2005 5 35 57 - 28 29 13
Wimmera 2 60 60 - 55 55 26
Mallee 7 12 54 - 3 7 0
Western 2010 25 40 73 18 35 33 5
Wimmera 35 60 74 18 57 54 9
Mallee 13 13 72 19 11 10 0

9. Most recent VIC Group A resistance
Plant Science
Consulting
What do these results mean?
10% resistance- seeds/plants collected over all paddock
90% resistance- seeds/plants collected from a small patch

10. Most recent VIC Group B/C resistance
Plant Science
Consulting

11. Most recent VIC Group M resistance
Plant Science
Consulting

12. Relationship within Group A’s
and B’s in resistant ryegrass

13. Ryegrass resistance- Group A’s
FOPS DEN DIM
If resistant
to below:
Hoegrass Verdict Targa Axial Achieve Select Factor
Hoegrass - R R ? ? ?
?
Verdict R - R
? ? ? ?
Targa R R -
? ? ? ?
Axial R R R - R
? ?
Achieve R R R R -
? ?
Select R R R R R -
?
Factor R R R R R R -
Rate response: Select, Factor, Select + Factor

14. Ryegrass resistance- Group B’s
Sulfonylureas IMI’s TP’s
If resistant to
below:
Logran Glean
Hussar
(ryegrass)
Atlantis
(wild oats)
Intervix/
OnDuty
Crusader
Logran - R ? ? ? ?
Glean R - ? ? ? ?
Hussar R R - R ? R
Atlantis R R R - ? R
Intervix R R R ? R ? - R ?
Crusader R R R R ? -

15. Why isn’t ryegrass controlled with Select?

16. Different resistance occurs in a single paddock:
Group A target site resistance
2078 25
2041 3
2078, 2041 11
2078, 2088 5
2041, 1781 1
1781, 2041,
2078
1
2041, 2078,
2088
1
Paddock 1
• GROUP B target site resistance same senario
Paddock 2 Paddock 3
ACCase Target
site mutations

17. Mutation 1998 2003 2008
1781 6 8 13
2027 10 7 6
2041 40 32 43
2078 13 13 21
2088 11 6 19
2096 1 1
1781, 1999 1
1781, 2027 1
1781, 2041 3 2 14
1781, 2078 3 3
1781, 2096 2
1999, 2041 1
1999, 2078 3
2027, 2041 2 2
2027, 2078 3
2041, 2078 3 5 4
2041, 2088 1 3
2078, 2088 6 3
2078, 2096 2
2088, 2096 1
Distribution of
ACCase mutations
in SA

18. Herbicide tactics at different stages to
control weeds
 Knockdowns (don’t overuse Gly) vs RR-canola
 Rotate between different modes of action
 Trifluralin, Avadex, Boxer Gold, Sakura, Kerb (IBS)
 In-crop (Group A & B’s) resistance.
Opportunities exist- use Herbicide Resistance
Testing vs overuse of Sakura/ Boxer Gold!
 Seed-set: Crop topping- canola, pulses, wheat

19. Successful weed control =
integrated weed management
1. Effective herbicides
• Knockdown
• Pre-emergence
• Post-emergence
• Seed-set stage
2. Non-herbicide strategies
3. Resistance testing
“when on a good thing don’t stick to it!!

20. IWM Crop Competition tactics
• Crop competition- barley-oats-trit-wheat-durum
• Crop choice- cereals vs broadleaf crops
• Seeding rate/ Crop density
• Row Spacing
• Cultivar choice
• Optimum planting time
• Seeding depth
• Seed vigor (Quality testing)
• Fertilizer timing
• Pest and disease management

21. Optimal timing
Anthers
Annual ryegrass at flowering (anthesis)

22. Crop-topping wild radish

23. Seedbanks- the seed in your paddock
• Surviving weeds set seed
• Low numbers of resistant weeds can set lots of seeds
• Seed longevity
– Differs between species
– Left on surface vs burial (tillage systems)

24. Managing the Weed Seed Bank-
conventional tillage
1993 1994 1995 1996 1997 1998 1999
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Beans Wheat Pasture Pasture Pasture Canola
2 Cultivations
Trifluralin
Diclofop-methyl
Cultivation
Glyphosate
Trifluralin
Clethodim
Haloxyfop-ethyl
Windrow
Mechanical
top
Mechanical
top
Mechanical
top
Spraytop
Year
Annualryegrass(seedm
-2
)

25. Successful farmers stop weed seed-set
Non-herbicide
– Green manure
– Hay, Silage
– Competitive crops
– Chaff cart
– Harrington Seed Destructor
– Burning stubbles/ wind rows
Herbicide
– Brown manure
– Crop topping
– Pasture topping
– Wick-wiping (lentils)

26. Burning Header Rows

27. NEW HERBICIDES
 Adelaide University is investigating:
 New MoA herbicides selective in wheat & canola
 New non-selective knockdown herbicide

28. What are your herbicide options?
Resistance testing
www.plantscienceconsulting.com.au
PLANT SCIENCE CONSULTING

29. Results using Seed Testing
Herbicide
Product
Rate
Herbicide
Group
Farmer
paddock
(g or ml/ha)
Surviva
l
(%)
Rating
Verdict + 1% Hasten 85 A-FOP 70 RR
Select + 1% Hasten 250 A-DIM 20 R
Select + 1% Hasten 500 A-DIM 0 S
Hussar + 1% Hasten 200 B-SU 90 RRR
Atrazine + 0.2% BS1000 2000 C 0 S
Triflur X 1000 D 0 S
What’s the outcome if farmer had chosen Verdict?

30. Results Ratings
RRR
RR
R

31. What tests are there?
1. During the growing season
• Syngenta Herbicide Resistance Quick-Test
• Test for resistance on surviving weeds
• Grasses mainly
• 4-5 weeks
2. At end of season (pre-harvest)
• Seed testing
• 8-10 weeks
• Dormancy breaking easy (wild radish, wild oats, ryegrass etc.)
• Seedlings transplanted
3. Crop Seed Quality Testing
• Germination, Vigor, TSW,
• Clearfield testing- wheat/ barley/ canola
Resistance testing
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PLANT SCIENCE CONSULTING

32. Testing: www.plantscienceconsulting.com.au
Testing Plants Testing Seed

33. Life Impact The University of Adelaide
Two main species
of Brome
• B. diandrus (Great Brome)
– medium rainfall
regions
– generally earlier
germination
• B. rigidus (Rigid Brome)
– lower rainfall regions
– late and staggered
germination
Herbicide resistance in Brome

34. Life Impact The University of Adelaide
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

35. Life Impact The University of Adelaide
Why Brome is a problem?
• Widely distributed
• Distribution increasing in no-till cropping
• Wide germination window
• Limited herbicide choice in-crop
– Wheat: Group B herbicides
– Broadleaf crops: Group A herbicides
• Herbicide resistance is developing
• IWM crucial eg. hay etc to stop seed-set.
(herbicides alone not the solution)

36. Life Impact The University of Adelaide
Multiple germinations
• Knockdown, pre-emergent, post-emergent
(dead plants), second post-m required.

37. Life Impact The University of Adelaide
Group A Resistance- Verdict

38. Life Impact The University of Adelaide
Group B IMI Resistance
(1800ml/ha Intervix)

39. Life Impact The University of Adelaide
Glyphosate resistance-
Maitland SA & Ouyen Vic.
Increasing rate improves control
Target site overexpression- eg. GLY resistance in brome

40. Brome 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 -
Can get rate response improving control

41. 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 ? -

42. Life Impact The University of Adelaide
Weed Control- in crop
• Knock-down (non-selective)- delayed
emergence!
• Pre-emergent herbicide mixes
– Trifluralin, Metribuzin, Sakura etc.
• Post-emergent herbicides
– Group A: Targa, Verdict, Select- dicot crops
– Group B: Atlantis, Crusader, Monza- wheat
– Group B: Intervix, Midas- Clearfield w/b/c
• Limited choice of different MoA herbicides
• Increased reliance on herbicides -> resistance

43. Life Impact The University of Adelaide
Brome grass control at Pira, Vic 2013
Untreated control
Sakura + Avadex Xtra
Source: M Witney (DM)

44. Life Impact The University of Adelaide
Efficacy of pre-em herbicides and brome seed germination
Slide 44
Trif750
Trif1500
Trif3000
Bromus diandrus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
a
60g/ha
Sakura
120g/ha
Sakura
240g/ha
Bromus diandrus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
n
75g/ha
M
etribuzin
150g/ha
M
etribuzin
300g/ha
Bromus diandrus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
Trif750
Trif1500
Trif3000
0
20
40
60
80
100
Herbicidedamage(%)
Bromus diandrus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
Sakura
60g/ha
Sakura
120g/ha
Sakura
240g/ha
0
20
40
60
80
100
Herbicidedamage(%)
Bromus diandrus
T-0
T-3
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
Herbicidedamage(%)
Bromus diandrus
T-0
T-3
T-5
T-7
T-10
T-12
T-14
b
d
f
Trifluralin
Sakura
Metribuzin

45. Managing broadleaf weed
resistance
wild radish,
Indian hedge mustard,
sowthistle

46. Wild Radish-
Wild
Radish
Year Region Glean 2,4-D
2009 S-Vic 0/15 0/15
2011 Vic Northern 0/2 1/2
Directed resistance testing:
Group B/F/I resistant wild radish detected in SA and Vic

47. Wild Radish
 Genetically diverse like ryegrass.
 Cross pollinates so resistance genes are transferred (= ryegrass)
 Seedbank life: (6-8+ yr) exposure to same MoA. Not all seeds
germinate in following year.
 Stacking of resistance (multiple resistance) = ryegrass
 Rotate MoA groups B, C, F, H, I, even if cheaper herbicides working
 Use full rates!!
 Spray early- younger resistant weeds can be killed
– Especially contact herbicides- bromoxynils, brodals, velocity
 Multiple herbicide timings- control new flushes

48. Sowthistle (% resistant samples)
Sowthistle
Year Region Glean 2,4-D
2009 S-Vic 0 0
2010 Vic Western 90
2011 Vic Northern 92
2012 SA Mallee/SE 80
The next big weed resistance problem!!
Directed resistance testing:
Group I resistance se SA
Group M resistance in s-NSW

49. Indian Hedge Mustard
(% resistant samples)
Indian Hedge Mustard
Year Region Glean Eclipse 24D
2008 SA Mid north 54 - 45
2013 SA Mid north 25 13 0
2009 SA Eyre Peninsula 52 57 0
2010 Vic Western 35 28 0

50. Indian Hedge Mustard
 Western Victoria- IHM = incidence in 15% of
paddocks
 Reliance on Group B/I I resistance  B/I resistance
 SA - Group B and I resistance (stacked resistance)
 Western Vic:
– 3 cases: resistance to Brodal (3 L/ha)
– 1 case Atrazine (3 kg/ha)
– Mostly self-pollinated (pollen transfer very rare)

51. The End
Plant Science
Consulting