2014 cca presentation- goondiwindii 16 july 2014 copy

1. Herbicide resistance in wild oats &
barnyard grass & resistance testing
Dr Peter Boutsalis, Dr Jenna Malone,
Christopher Preston & Gurjeet Gill.
School of Agriculture, Food and Wine
University of Adelaide
Plant Science
Consulting

2. Why does herbicide resistance occur?
 Herbicides don’t cause resistance!!
 Resistance is naturally present.
 Herbicides select and enrich resistance
 Ryegrass/ wild radish- obligate outcrossing so
combine weak resistance  strong resistance
 Wild oats/ barnyard grass mostly self pollinate.

3. 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!

4. 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!!

5. If continuous use, 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

6. Life Impact The University of Adelaide
Resistance in wild oats?
• 1000+ Group A resistant cases
• Group B’s- few confirmed
• Mataven (Group Z)
• What is the information from random
• surveys?

7. GRDC sponsored survey GOA 2013
– Wild oats
 Survey area: Coonamble to Narromine, Nyngen to
Coolah
 40 wild oat samples
 Trends- incidence of resistance:
– Very low : Atlantis, Verdict, Select
– Low : Axial
– Medium : Mataven
– High: Topik

8. Wild oat herbicide resistance
How real is the threat ?
NGA survey Oct 2007
(Richard Daniel)
Acknowledgment: Bayer CropScience, Nufarm and
Syngenta who all contributed to the cost of testing

9. How widely did we survey ?
• Involved 34 agronomists from Sthn Qld to the
Liverpool Plains and west to Walgett and Mungindi
• 61 seed samples from ‘high risk’ situations (Paddocks with
wild oat herbicide performance issues in 2007 or having previous concerns)
• 36 seed samples from ‘random level’ situations (Nearly
all paddocks unsprayed for wild oats in 2007. Best estimate of ‘average
resistance levels’)
• All samples tested by Peter Boutsalis (Plant Science
Consulting) with a common range of 9 herbicides

10. When were herbicides applied ?
Products Herbicide group
(sub group)
Application timing
TriflurX +
Avadex Xtra
D + E Pre-emergent, directly on
seed then covered with 1
cm soil, to simulate IBS
Wildcat, Topik
and Verdict
A (fop)
3 leaf stageAxial A (den)
Select A (dim)
Atlantis B
Mataven Z Jointing to first node, to
simulate SST

11. Incidence
(% of samples with ANY resistance)
0
20
40
60
80
100
Wildcat
300
mL/ha
Topik
65
mL/ha
Verdict
50
mL/ha
Axial
150
mL/ha
Mataven
1875
mL/ha
Atlantis
330
mL/ha
Select
175
mL/ha
TriflurX
+
Avadex
Xtra
%ofsampleswithANYresistance
High risk (61 samples) Random level (36 samples)

12. Were samples resistant to
more than one herbicide ?

13. Frequency of multiple herbicide
resistance
59% of ‘high risk’ samples had
resistance to 3 or more different
herbicides
0
20
40
60
80
100
0 1 2 3 4 5 6 7 8
Resistance to number of herbicides
%ofsamples
High risk (61 samples) Random level (36 samples)
15% of ‘high risk’ samples were NOT resistant to any herbicide
78% of ‘random level’ samples were NOT resistant to any herbicide

14. Conclusions
1. Herbicide resistant wild oats are a real and
escalating issue in the north.
2. Testing of ‘escapes’ in individual paddocks MUST
become a key management practice. Test to see
what will WORK
3. No single product/ strategy will provide the solution

15. Life Impact The University of Adelaide
Understanding Group A herbicide
resistance
Peter Boutsalis, Jenna Malone, Christopher Preston, Sam
Kleemann, Gurjeet Gill
School of Agriculture, Food & Wine, University of Adelaide,

16. 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

17. Photos
Axial
regrowth
300 vs 150ml Axial
Avadex

18. 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 ? -

19. Mechanisms of resistance

20. Mechanisms of resistance
How are resistant plants different to susceptible plants?
 1. Metabolic resistance
 2. Target site resistance
 3. Uptake & translocation
 4. Sequestration
 5. Increased expression of target site - eg.
glyphosate resistance in brome

21. Metabolic resistance
 Plant enzymes detoxify the
herbicides before they reach the
target site
 The herbicide will kill the plant if it
reaches the target site in
sufficient concentration
 Occurs in wild oats, ryegrass
Location of sensitive target
site. Plant is resistant
X
Herbicide

22. Target Site Resistance
• Some herbicides bind to single but different
enzyme:
– Group A (ACCase),
– B (ALS),
– C (PS2) ,
– M (EPSPS)
• Variations in efficacy within a Group can
occur eg. between Topik, Verdict, Axial,
Achieve, Select.

23. Target Site Resistance
• Herbicides are chemically different and bind to
the target-site enzyme slightly differently
• Different mutations change the shape of the
target site affecting cross-resistance
H2
H1
Target
enzyme
Target
enzyme
Target
enzyme
H2
H1
H2 H1

24. Group A target site- ACCase gene
Group A biniding site

25. Group A resistance mutations
1781 1999 2027 2041 2078 2088 2096
Biotin carboxylase Biotin carrier Carboxyltransferase
ACCase gene

26. Distribution & understanting of Group A
resistance using DNA technology
2078 25
2041 3
2078, 2041 11
2078, 2088 5
2041, 1781 1
1781, 2041, 2078 1
2041, 2078, 2088 1
Paddock 1 Paddock 2 Paddock 3
ACCase Target
site mutations

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

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

29. Life Impact The University of Adelaide
Glyphosate resistance in awnless BYG
• 70 populations confirmed glyphosate resistant
• Lots more unconfirmed
• Cross-pollination low: 1.4%
• Mechanisms of resistance
• 1 = Target site resistant
• 10 = ‘other’ mechanism
• Temperature effects

30. Glyphosate resistant barnyard grass
0
10
20
30
40
50
60
70
80
90
100
0 500 1000 2000 4000
Survival(%)
Glyphosate (ml/ha)
S
A533.1
A1352.1
A491

31. Life Impact The University of Adelaide
Temperature and glyphosate resistance
• In some glyphosate resistant biotypes
temperature affects efficacy.
• Related with the resistance mechanism
20oC 30oC

32. Resistance Testing
 Would you pay $300 to ensure you don’t choose the
wrong herbicide??
 Buy effective herbicides (save money)
 Reduce crop competition yield
 Reduce weed infestations restrict crop rotation
choice
 Avoid increase resistant seedbanks

33. “Know your enemy”
Testing for Herbicide Resistance

34. 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

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

36. Post Plants

37. 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

38. Make cuttings

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

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

41. 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 RRR
Select + 1% Hasten 200 A-DIM 20 R
Hussar + 1% Hasten 200 B-SU 90 RRR
Atrazine + 0.2% BS1000 2000 C 0 S
Triflur X 1000 D 0 S

42. Results Ratings
RRR
RR
R

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