2015 vic- berriwillock-landmark-resistance-march

Herbicide resistance in western Victoria

Dr Peter Boutsalis, University of Adelaide & Plant Science Consulting

Plant ScienceConsulting

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

Incidence of Herbicide resistance

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)

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

Testing of survey samples

Ryegrass

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.

Most recent VIC Group A resistance


What do these results mean?

10% resistance- seeds/plants collected over all paddock

90% resistance- seeds/plants collected from a small patch

Most recent VIC Group B/C resistance


Most recent VIC Group M resistance


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 ? -

Why isn’t ryegrass controlled with Select?

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

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

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

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!!

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

Optimal timing

Anthers

Annual ryegrass at flowering (anthesis)

Crop-topping wild radish

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)

Managing the Weed Seed Bank- conventional tillage

1993 1994 1995 1996 1997 1998 19990

2000

4000

6000

8000

10000

12000

14000

16000

18000Beans Wheat Pasture Pasture Pasture Canola

2 CultivationsTrifluralin

Diclofop-methylCultivationGlyphosateTrifluralinClethodim

Haloxyfop-ethylWindrow

Mechanicaltop

Mechanicaltop

Mechanicaltop

Spraytop

Year

An

nu

al r

yeg

rass

(se

ed m

-2)

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)

Burning Header Rows

NEW HERBICIDES

Adelaide University is investigating:

New MoA herbicides selective in wheat & canola

New non-selective knockdown herbicide

What are your herbicide options?

Resistance testing

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PLANT SCIENCE CONSULTING

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

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

www.plantscienceconsulting.com.au

PLANT SCIENCE CONSULTING

Testing: www.plantscienceconsulting.com.au

Testing Plants Testing Seed

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


Herbicide resistance- random surveys

Survey Year Verdict (%)

Select (%)

Atlantis (%)

South Australia Mallee 2007 0 0 33Mid North 2008 2 0 3Eyre Peninsula 2009 0 0 5 Victoria

Western 2010 6 7 37Northern 2011 0 0 0


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)


Multiple germinations• Knockdown, pre-emergent, post-emergent

(dead plants), second post-m required.


Group A Resistance- Verdict


Group B IMI Resistance (1800ml/ha Intervix)


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 -

Can get rate response improving control

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 ? -


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


Brome grass control at Pira, Vic 2013

Untreated control

Sakura + Avadex Xtra

Source: M Witney (DM)


Efficacy of pre-em herbicides and brome seed germination

Slide 44

Trifluralin

Sakura

Metribuzin

Managing broadleaf weed resistance

wild radish,

Indian hedge mustard,

sowthistle

Wild Radish-

Directed resistance testing:Group B/F/I resistant wild radish detected in SA and Vic

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

Sowthistle (% resistant samples)

The next big weed resistance problem!!

Directed resistance testing:Group I resistance se SA Group M resistance in s-NSW

Indian Hedge Mustard (% resistant samples)

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)

The End


Education

2015 vic- berriwillock-landmark-resistance-march