2015 hres- ikc-ballarat- 25 june vic

1. Herbicide resistance in Victoria
Dr Peter Boutsalis,
Plant Science Consulting &
University of Adelaide
IKC- June 25 2015
Plant Science
Consulting

2. Outline
 Why does herbicide resistance occur
 Frequency of resistance
 Ryegrass
 Wild oats
 Broadleaf weeds
 Glyphosate resistance
 Herbicide resistance testing
 Integrated weed management

3. 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

4. Frequency of resistance

5. Frequency of resistance
 Group A: 1 in 500,000 naturally resistant
 Group B: 1 in 20,000 naturally resistant (25X)
 Group M: very rare but its here!

6. Frequency of Group A Resistant
Individuals in a 100 ha Paddock
Plant Density
1 m-2
10 m-2
100 m-2
1000 m-2
Plants
1 million
10 million
100 million
1 billion
Resistant Individuals
2
20
200
2000
(assume a frequency of 1 R/ 500,000 plants)
 So a paddock with a low density of survivors may not look threatening
but if they are resistant  resistant seedbank!!

7. 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

8. Incidence of
Herbicide resistance
across south-eastern
Australia

9. 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)

10. Uni of Adelaide random weed surveys between 2004-2012
(paddock surveyed)

11. Testing of survey samples

12. Ryegrass

13. 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

14. Ryegrass resistance in N-Victoria
Northern Victoria
Results of weed survey of 120 paddocks chosen at random in 2006 & 2011 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.

15. NSW & Tasmanian results courtesy of John Broster (Charles Sturt University)
WA results courtesy of AHRI, University of Western Australia
Resistance defined where ≥ 20% survival in a pot test
Region Year Trifluralin Hoegrass Glean Intervix Achieve Axial Glyphosate Select
SOUTH
AUSTRALIA
Northern Mallee 2012 20 9 70 36 7 0 0
Southern Mallee 2012 69 30 52 36 16 0 2
South East 2012 78 90 70 60 80 16 43
Central 2008 40 76 73 44 64 59 nt 40
Eyre Peninsula 2009 5 30 78 47 29 30 nt 11
Kangaroo Island 2009 0 46 67 45 55 50 nt 9
VICTORIA
Western 2010 25 40 73 18 35 33 nt 5
Northern 2011 0 55 87 29 31 31 0 8
Southern 2009/14 0/3 79/82 88/93 39 84 68 nt 23
SE- NEW SOUTH
WALES
2008 6 81 70 nt nt nt nt 21
TASMANIA 2009 0 11 23 nt nt nt nt 0
WA 2003 0.2 37 68 nt 13 nt nt 0.5

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

17. 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

18. 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 ? -

19. Why isn’t ryegrass controlled with Select?

20. Distribution of Group A resistance using
molecular studies
2078 25
2041 3
2078, 2041 11
2078, 2088 5
2041, 1781 1
1781, 2041,
2078
1
2041, 2078,
2088
1
Paddock 1
• “Resistance occurs from a single plant in a paddock” is unlikely for Group A and B’s
Paddock 2 Paddock 3
ACCase Target
site mutations

21. 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

22. 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
 Seed-set: Crop topping- “canola”, pulses, wheat

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

24. Life Impact The University of Adelaide
Product X applied IBS

25. Life Impact The University of Adelaide
New pre-em herbicide research

26. Herbicide Resistance in
Wild oats

27. Life Impact The University of Adelaide
Resistance in wild oats
• Group A resistant- big problem in northern NSW/
southern QLD.
• Group B’s- increasing
• What is the info from random surveys?

28. Herbicide Resistance in Wild Oats
from Random Surveys
HERBICIDE West Victoria NE Victoria
Data is % of random samples (Resistance = survival ≥20%)
2005 2010 2006 2011
Paddocks 35/ 112 (31%) 38/ 121 (31%) 85/ 118 (72%) 40/115 (35%)
Topik 10 10 8 8
Verdict - 5 - 0
Axial - - 2 -
Atlantis - 0 0 0
Mataven - 2 12 5
Select 0 - 0 -

29. Wild Oats resistance- Group A’s
FOPS DEN DIM
If resistant to
below:
Topik Verdict Targa Axial Achieve Select Factor
Topik - ? ? ? ? ? ?
Verdict R - R ?
?
? ?
Targa R ? - ?
?
? ?
Axial R ? ? - R ? ?
Achieve R ? ? R ? - ? ?
Select R ? ? ? ? - ?
Factor R ? ? ? ? R? -
Rate response: 150ml/ha Axial vs 300ml/ha Axial
Crop-topping with Topik/ Axial

30. Photos
Axial
regrowth
300 vs 150ml Axial
Avadex

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

32. Differences between ryegrass and
wild oats
 Ploidy- 2 vs 6 copies of each gene
 Pollination- cross vs self
 Seeds/ plant
 Is frequency of resistance different between species?

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

34. BLW issues in Victoria
 Wild radish- resistance to Group B/I/F
 Milk thistle- resistance to Group B (I/M)
 Mustards- Group B (C/F/I)
Glyphosate resistance confirmed in NSW

35. 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
 Resistance starting in eastern Australia
 Rotate MoA groups B, C, F, H, I, even if cheaper herbicides working
 Use full rates!!
 Spray early- younger resistant weeds can be killed

36. Life Impact The University of Adelaide
Glyphosate Resistance
Christopher Preston, Jenna Malone and Peter
Boutsalis
School of Agriculture, Food & Wine, University
of Adelaide

37. Life Impact The University of Adelaide
What we have so far
Annual ryegrass Barnyard grass Liverseed grass
Fleabane Windmill grass Great brome

38. Life Impact The University of Adelaide
Glyphosate resistant ryegrass
Situation Number of
sites
States
Broadacre
cropping
Chemical fallow 29 NSW
Winter grains
Irrigated crops
82
1
Vic, SA, WA, NSW
SA
Horticulture Tree crops 5 NSW, SA
Vine crops
Vegetables
21
2
SA, WA
Vic
Other Driveway 4 NSW, Vic, SA, WA
Fence line /Crop
margin
Around buildings
63
2
NSW, SA, Vic, WA
NSW
Irrigation channel
/Drain
12 NSW, SA, Vic
Airstrip 1 SA
Railway 2 WA, NSW
Roadside 85 SA, NSW, WA
One population = 10L/ha (roadside in southern Vic).

39. Plant Science
Consulting
1000ml/ha 1500ml/ha
Increasing rates of Glyphosate
1000ml/ha 1500ml/ha

40. Life Impact The University of Adelaide
Control of Gly-R ryegrass on fence lines
with herbicide mixtures
0
50
100
150
200
250
300
350
Seedheads/m2
Herbicide treatment
Untreated
Glyphosate
Glyphosate
mixtures
Paraquat
mixtures
Experimental
Doubleknock
2L/ha glyphosate
2 applications of Spray.Seed

41. Life Impact The University of Adelaide
 Glyphosate resistance along fenceline  in crop
Response of in-crop ryegrass to glyphosate
0
10
20
30
40
50
60
70
405 810 1620
%Survival
Glyphosate rates (g a.e ha-1)
fence line 15m in crop 30m in crop 50m in crop

42. Glyphosate resistance

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

45. 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
PLANT SCIENCE CONSULTING
www.plantscienceconsulting.com

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

47. 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?
Q. Will Axial/ Achieve work??

48. Results Ratings
RRR
RR
R

49. Quick-Test: Monitoring: identify
survivors
Why has this individual survived
and the others haven't?
Is it resistant?

50. Post Plants

51. Growth stage = 1-2 leaf to advanced tillering
Best stage is early tillering
Rinse soil off roots
Plants can be trimmed
Leaves dry
Add NO water
Quick-Test: collect plants

52. Make cuttings

53. Cuttings and re-growth
1. Cuttings
2. Regrowth 5-10 days later
3. Spray
Compared to Standard Resistant and Susceptible biotypes in every test

54. Assess 2-3 weeks after spray
Test for any post emergence herbicide

55. CROP SEED QALITY TESTING
Crop Seed Quality Testing

56. Why test crop seed?
Maximise crop establishment & competition with weeds
Germination- establishment under good conditions
Vigor- establishment under sub-optimal conditions/ heavy weed
burdens
Seed weight  accurate seeding rates/ good vigour
Crop Seed Quality Testing

57. For more information
www.plantscienceconsulting.com.au

58. 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!!

59. 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

60. 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)

61. Managing the Weed Seed Bank
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
)

62. 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)

63. Burning Header Rows

64. The End
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