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 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