Herbicide resistance and management decisions

Fabián Menalled & Mary Burrows Land Resources and Environmental Sciences Plant Sciences and Plant Pathology Montana State University

Overview • Herbicide resistance – Definitions – Review of cases – Approaches to minimize the selection of herbicide resistance

Overview • Herbicide resistance – Definitions – Review of cases – Approaches to minimize the selection of herbicide resistance

• Management decisions

Take Home Message A pest problem doesn’t always have a pesticide solution

Overview • Herbicide resistance – Definitions – Review of cases – Approaches to minimize the selection of herbicide resistance

• Management decisions

Herbicide Resistance is NOT due to 1. Sprayer skips or plugged nozzles 2. Weather problems that cause poor control 3. Plants that are ‘naturally tolerant’ to the herbicide 4. Genetic changes caused by the herbicide

Herbicide Resistance is The ability of a plant to survive and reproduce after treatment with a dose of herbicide that would normally kill the plant

What should I be looking for?

Susceptible Resistant

What should I be looking for?

Where do Resistant Weeds Come From? It’s all about selection…..

Herbicide application: selection pressure for resistant plants

DNA

DNA mutation: allows resistance to a herbicide

Succeeding generations are also resistant

Herbicide application: selection pressure

Reproduction (sets seeds)

Resistance passed on to next generation

Is it a serious issue? December 21, 2012: • 396 Resistant Biotypes, • 210 Species (123 dicots and 87 monocots) Source: International survey of herbicide resistant weeds (www.weedscience.org)

Distribution of Herbicide Resistant Biotypes > 131 biotypes

Roundup Ready Crop Acres

Source: USDA - ERS

Confirmed glyphosate-resistant weed populations

Source: Heap 2012

Glyphosate Resistance • 21 species worldwide • USA 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Amaranthus palmeri, Palmer amaranth Amaranthus tuberculatus, Common waterhemp Ambrosia artemisiifolia, Common ragweed Ambrosia trifida, Giant ragweed Conyza bonariensis, Hairy fleabane Conyza canadensis, Horseweed Echinochloa colona, Junglerice Eleusine indica, Goosegrass Kochia scoparia, Kochia Lolium multiflorum, Italian ryegrass Poa annua, Annual bluegrass Sorghum halepense, Johnsongrass

A Brief History of Kochia Control in MT Before 1945: hand weeding (lots of kids) 1950: 2,4-D & other auxinic herbicides 1980: First SU herbicides introduced (Glean, Telar, Ally) 1984: Photosynthesis II inhibitors resistance (Atrazine) 1987: SU-resistant kochia discovered (Glean, Telar, Ally) 1990: Back to auxinic herbicides (Dicamba) 1994: Dicamba-resistant kochia appears 2000s: Fluroxypyr (Starane) and 2-4,D resistance 2005: Glyphosate (Round-up) failure complains 2012: Glyphosate (Round-up) resistance

Kochia, glyphosate resistant Stahlman and Godar, Kansas State Univ.

Susc. Control

Res. 0X

1X

2X

4X

What if? (or When…)

Amsterdam, MT Chem fallow, no-till Application: May 1, 2012

Management of Glyphosate Resistant Kochia • Goals – Early spring burndown herbicide with good kochia efficacy – Evaluate herbicides with soil activity on kochia: control through mid-July • Kochia establishment after mid-July is unlikely due to dry upper soil profile

Management of Glyphosate Resistant Kochia • Methods – Gramoxone Super (paraquat): burndown herbicide – Tank-mix partners: Atrazine, Sencor, Corvus – Valor, Spartan, and Spartan Charge: burndown and soil residual – Volunteer wheat and downy brome: Gramoxone Super or Select

LSD = 7.39

Percentage Control

Percentage Control

LSD = 7.39 LSD = 8.35

Approximate Price

(Source 2012 North Dakota Weed Control Guide) Treatment

Cost $/A (high rate)

Roundup

7.50

Select

7.50

Gramoxone Super

11.50

Gramoxone Super + Atrazine

15.50

Gramoxone Super + Sencor 75 DF

19.50

Gramoxone Super + Atrazine + Sencor 75DF

23.50

Gramoxone Super + Corvus

42.30

Gramoxone Super + Corvus + Sencor

50.30

Select + Valor

24.00

Select + Spartan

35.65

Select + Spartan Charge + Valor

50.96

Select + Spartan + Distinct

61.65

Management of Glyphosate Resistant Kochia • Another study from Kansas – Resistance to glyphosate and 2,4-D – POST-applied herbicide – Some of the products are not commonly used in MT

Lorox Kixor (~ Sharpen)

After Brachtenbach and Stahlman, 2012

Laudis

Treatments a Glyphosate b Glyphosate b + dicamba + NIS Kixor + Lorox + MSO Kixor + atrazine + MSO Kixor + paraquat + MSO Laudis + dicamba + MSO Laudis + dicamba + Sencor +MSO Laudis + Starane+ MSO Impact + atrazine + MSO Impact + glyphosate b+ MSO Paraquat + Lorox + NIS Paraquat + Lorox + Sencor + NIS Glyphosate b+ paraquat + dicamba + NIS a.

All treatments included 2% w/v dry ammonium sulfate b. Roundup PowerMax

Retail $/a 7.50 11.44 22.76 9.455 20.89 23.45 33.03 27.15 26.46 30.67 28.47 38.04 23.67

Gramoxone (paraquat) • Restricted use pesticide • Acute toxicity – Fatal if inhaled. May be fatal is swallowed. Harmful in contact with skin.

• Worldwide: 25 resistant species (43 resistant biotypes) in 13 countries • Australia: multiple resistance with glyphosate

More recommendations… • Roundup (32 oz/A) thank mixed with Dicamba (0.5 lb ae/A) + 2,4D (0.5 lb ae/A)

But…

Kochia sprayed with 2.4-D - Growth Regulator -

Unsprayed

Susceptible Control

Resistant Sprayed

Weeds with Resistance to Multiple Modes of Action

Source www.wssa.net

How Can We Prevent & Manage Herbicide Resistance?

Questions, so far?

Selection Pressure is Affected by “Better” herbicide = more chances of selecting for resistance

How Can We Prevent the Selection of Resistant Biotypes? Don’t rely on just that “great” herbicide * Use different Mode of Actions

Rotate Herbicides or Tank Mixtures, That is the Question

Tank Mixes and Evolution of Resistance • Mixing partners 100 – Different site of action

– Similar efficacy and persistence

A in rotation

60

B in rotation A & B in mixture

80

% Resistance

A or B used alone

40 20 0

1

3

5

7 9 Years

11 13 15

Assumptions In the long term, selection of • Target site dominant inheritance Adapted from Powels et al. 1997 •multiple Outcrossing species herbicide resistance

How Can We Prevent the Selection of Resistant Biotypes? Don’t rely on that “great” herbicide * Use different Mode of Actions – SHORT TERM SOLUTION! Incorporate other mortality factors * Cultural practices – Crop rotation

Cheatgrass density (no. m-2)

Crop Rotation and Cheatgrass Density 1200 1000 800 600 400 200 0 1987

1988

1989

1990

1991

Year

1992

1993

1994

Wheat-canola, no-till

Wheat-canola, till

Continuous wheat, no-till

Continuous wheat, till After Blackshaw 1994

How Can We Prevent the Selection of Resistant Biotypes? Don’t rely on that “great” herbicide * Use different Mode of Actions – SHORT TERM SOLUTION! Incorporate other mortality factors * Cultural practices - Crop rotation - Crop competitiveness

Source: Menalled and Miller

Short wheat variety

Tall wheat variety

High weed seed production

Low weed seed production

How Can We Prevent the Selection of Resistant Biotypes? Don’t rely on that “great” herbicide * Use different Mode of Actions – SHORT TERM SOLUTION! Incorporate other mortality factors * Cultural practices - Crop rotation - Crop competitiveness * Minimize weed seed movement

Standard weed management + weed shed prevention

24% expansion over 6 years

1997

2002

Standard weed management conducted at the field level

1997 After H. Beckie, Agri-Food Canada @ Saskatoon

2002

270% expansion over 6 years

How Can We Prevent the Selection of Resistant Biotypes? Don’t rely on that “great” herbicide

AN INTEGRATED *DEVELOP Use different Mode of Actions

– SHORT TERM SOLUTION! WEED MANAGEMENT Incorporate other mortality factors * Cultural practices

PROGRAM

- Crop rotation

- Crop competitiveness * Minimize weed seed movement

Overview Herbicide resistance – Definitions – Review of cases – Approaches to minimize the selection of herbicide resistance

• Management decisions

Questions, so far?

Take Home Message

A pest problem doesn’t always have a pesticide solution

LET’S

Nutrients Moisture

Light

Yield

Pinoxaden (Axial) 1X = 8.2 oz/A

0X

1/8X

1X

3/16X

2X

1/4X

4X

1/2X

8X

Difenzoquat (Avenge) 1X = 4.25 L/100L

0X

1/2X

1X

2X

Imazamethabenz (Assert) 1X = 1.5 pts/A

0X

1/2X

1X

2X

Diclofop (Hoelon 3) 1X = 2.5 pts/A

0X

1/2X

1X

2X

Clethodim (Select) 1X = 6 oz/A

0X

1/2X

1X

2X

Quizalofop (Assure II) 1X = 8 oz/A

0X

1/2X

1X

2X

Other herbicides tested… • Puma, Everest, Achieve, Fargo, Fusilade

Clearfield wheat: high risk of ALS resistance. No more than 2 out of 4 years (unless other control practices are implemented)

Decrease Seeding Rate Weed competition

Pathogen Control

Decrease Seeding Rate Weed competition

Pathogen Control

Wheat Stem Sawfly Management • Solid stem varieties (Choteau) • But – Low yield potential – Low competitive ability

Wheat Stem Sawfly Management • Solid stem varieties (Choteau) • But – Low yield potential – Low competitive ability – Increasing seeding rate results in • Lose of stem solidness • Increase Fusarium pressure

Given an specific goal, your task is to manage wild oats with multiple herbicide resistance, glyphosate resistant kochia, Fusarium crown rot, & wheat stem sawfly