Herbicide resistance in SA
Dr Peter Boutsalis, Christopher Preston & Gurjeet Gill.
School of Agriculture, Food and Wine
University of Adelaide
Plant ScienceConsulting
Outline
Ryegrass Brome Glyphosate resistance Herbicide resistance testing Integrated weed management
Incidence of Herbicide resistance
Uni of Adelaide random weed surveys between 2004-2015(paddock surveyed)
Testing of survey samples
Ryegrass
Ryegrass resistance in Mid-North SA
Northern SA Results of random weed surveys 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.
Ryegrass resistance in SA Mallee & SE
Resistance defined where ≥ 20% survival in a pot test
Ryegrass resistance in Eyre Peninsula- 2009
Resistance defined where ≥ 20% survival in a pot test
Relationship within Group A’s and B’s in resistant ryegrass
Ryegrass resistance- Group A’sFOPS 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
Ryegrass resistance- Group B’sSulfonylureas 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 ? -
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
Life Impact The University of Adelaide
Brome Herbicide resistance- random surveys
Survey Year Verdict (%)
Select (%)
Atlantis (%)
Crusader(%)
Intervix(%)
South Australia Mallee 2012 0 0 51 59 0Mallee 2007 0 0 33 - -South East 2012 14 0 16 14 0Mid North 2013 0 0 40 - -Mid North 2008 2 0 3 - 0Eyre Peninsula 2009 0 0 5 - - Victoria
Western 2010 6 7 37 - -
Northern 2011 0 0 0 - 0
Atlantis resistant brome also resistant to Crusader and Monza
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
Life Impact The University of Adelaide
Multiple germinations• Knockdown, pre-emergent, post-emergent
(dead plants), second post-m required.
Life Impact The University of Adelaide
Group A Resistance- Verdict
Life Impact The University of Adelaide
Group B IMI Resistance (1800ml/ha Intervix)
Life Impact The University of Adelaide
Glyphosate resistance- Maitland SA & Ouyen Vic.
Increasing rate improves control
Target site overexpression- eg. GLY resistance in brome
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 -
Brome resistance- Group B’sSulfonylureas 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 ? -
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
Life Impact The University of Adelaide
Brome grass control at Pira, Vic 2013
Untreated control
Sakura + Avadex Xtra
Source: M Witney (DM)
Life Impact The University of Adelaide
Efficacy of pre-em herbicides and brome seed germination
Slide 24
Trifluralin
Sakura
Metribuzin
Life Impact The University of Adelaide
Glyphosate Resistance
Christopher Preston, Jenna Malone and Peter Boutsalis
School of Agriculture, Food & Wine, University of Adelaide
Plant ScienceConsulting
1000ml/ha 1500ml/ha
Increasing rates of Glyphosate
1000ml/ha 1500ml/ha
Glyphosate resistance
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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Testing: www.plantscienceconsulting.com.au
Testing Plants Testing Seed
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?
Results Ratings
RRRRR
R
Herbicide tactics at different stages to control weeds
Rotate between different modes of action
Trifluralin, Avadex, Boxer Gold, Sakura,
Propyzamide
In-crop (Group A & B’s) resistance. Opportunities
exist- use Herbicide Resistance Testing
Seed-set: Crop topping- canola, pulses, wheat
NEW HERBICIDES
Adelaide University is investigating:
New MoA herbicides selective in wheat & canola
New non-selective knockdown herbicide
IWM Crop Competition tactics that help herbicides work better!
• 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
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)
The End
Plant ScienceConsulting
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