2014: Herbicide Resistance Changes Agriculture Forever

Stanley CulpepperTifton, GA

Herbicide-resistance is not a new phenomenon!Its been happening since 1968!

The U.S. Wins the Gold Medal in Herbicide Resistance!!!!

Source: International Survey of Herbicide Resistant Weeds (10/4/12)

Confirmed Cases of Herbicide-Resistant Weeds in the United States

5

5

1119

1165

6

9

2

Source: International Survey of Herbicide Resistant Weeds (10/4/12)

24 20

8

26 4

CT-2DE-7HI- 4MD-11MA-2NH-2NJ-4RI-1VT-2

13

22 1622

22 4

2

27

17

13

10

8

5

13

21

18

7

10

1

11

122

Resistance Development

Economics, Effectiveness, and Ease of the

herbicide(s)

AND

Biology of the weed

Roundup Ready

Technology

Very Economical

Very Effective

Extremely Easy

Resistance Development

Economics, Effectiveness, and Ease are almost always the main factors

1. Single mode of action applied to large acreage2. Few or no alternative classes of chemistry used3. Little to no tillage4. Little to no rotation in crops5. Often in stressful environments when herbicide activity

is minimized6. Reduced herbicide rates, poor coverage, etc.. that

minimize activity

Tremendous Selection Pressure

Selection Pressure

Overuse of herbicide chemistry

Resistance

Herbicide Resistance: The acquired (inherited) ability of a weed population to survive a herbicide application that previously was known to control the population.

Palmer amaranth Changes Agriculture

Biological Attributes

Herbicide Resistance

2005-2011

What makes Palmer special?

1. Herbicide resistance?

Oh my, how great it was!!!!!!

WeatherMax 176 oz; POST 2”, 5”, and 8”

(at least 24 times more lb active than normally needed)

cotton

Weathermax 88 oz

Staple LX 10 oz

What makes Palmer special?

1. Herbicide resistance?

2. Growth rate?

Picture taken 7 am on 7-9-07

4 inches 52 hr

Picture taken 7 am on 7-9-07

1/2 inch 12 hr (overnight)

What makes Palmer special?

1. Herbicide resistance?

2. Growth rate?

3. Large stature?

Rapid Growth Becoming Extremely Large

What makes Palmer special?

1. Herbicide resistance?

2. Growth rate?

3. Large stature?

4. Competitive ability?

Crop Rotation

Yield Loss (%) from 1 AMAPA/row meter

What makes Palmer special?

1. Herbicide resistance?

2. Growth rate?

3. Large stature?

4. Competitive ability?

5. Reducing harvest efficacy?

Impact on Harvest

What makes Palmer a special?

1. Herbicide resistance?

2. Growth rate?

3. Large stature?

4. Competitive ability?

5. Reducing harvest efficacy?

6. Seed production?

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

230 K

25028 K

309 K

Giant ragweed

450 K

Number of Seed Produced per Plant Glyphosate-Resistant Weeds in US

Ragweed = Harrison et al. 2001; johnsongrass = Warwick and Black (1983); horseweed = Regehr and Bazzaz (1979); waterhemp = Nordby and Hartzler (2004); Palmer amaranth = Macrae et al (2009).

Johnson-grass

Horseweed Waterhemp Palmer amaranth

Palmer amaranth seed production allows for rapid field domination

Year 1 Year 3 to 4

What makes Palmer special?

1. Herbicide resistance?

2. Growth rate?

3. Large stature?

4. Competitive ability?

5. Reducing harvest efficacy?

6. Seed production?

7. Rapid spread?

Role of pollen movement and gene-flow in the spread of herbicide resistance

Pollen-flow can move genes across the landscape

And a trait becomes established in a new population

Traditional Grower Response To Resistance

1. It want happen to me!

2. Ok, its starting to happen to me so when will the next new

herbicide be here? (1992 was last new mode of action)

3. O *$&#, I got a mess. It’s on!

Traditional Grower Response To Resistance

1. It want happen to me!

2. Ok, its starting to happen to me so when will the next new

herbicide be here? (1992 was last new mode of action)

3. O *$&#, I got a mess. It’s on!

The challenge for Extension and Industry is figuring out how to skip steps 1 and 2 moving straight into step 3.

Helping Growers Respond More Quickly

1. Unified communication

2. Unbiased research defining potential impact from resistant

weed.

3. Provide management programs that are as simple and

economical as possible.

Herbicide input increased from 4.25 to 10.625 lb ai/A

2000-2005: Herbicide costs = $27.80/A

2006-2010: Herbicide costs = $68.00/A

Changes in Herbicide Management2002: $24/A 2010: $63/A

Roundup Burndown

Roundup POST 1

Roundup POST 2

Roundup + diuron PD

Roundup + Valor Burndown1

Gramoxone + Reflex + Direx PRE

Roundup + Staple POST 1

Roundup + Dual POST 2

Direx + MSMA PD

Photo by A.C. York 2010

2004: 17% of growers hand-weeded 5% cotton acres at $2.40/A

2010: 92% of growers hand-weeded 52% cotton acres at $23.70/A

Tillage is now a common scene

2004: 13.1% of cotton acres cultivated2010: 32.1% of cotton acres cultivated

Herbicide incorporation: 264,266 A (26.7%) Deep turn: 256,075 A last 3 yr

Current Cotton Situation

Cost to Manage Palmer in GA Cotton

1. Herbicide input: $68.00 per A $88 million

2. Hand weeding: $11.40 per A $15 million

3. Additional tillage: $5.84 per A $7.6 million

4. Yield loss ??? ????

$110 million

RR Herbicide Program Getting Better*

2010 2012

*Conditions first six wk after planting drier during 2012 than 2010.

Growers Making Good Decisions IS KEY!!!!!

1. Diversified (more than just spray, spray, spray)

2. Timely herbicide applications (residuals key!)

3. Understand Palmer amaranth biology

4. More effective weed management programs

Growers Making Good Decisions IS KEY!!!!!

4. More effective weed management programs

A. Herbicides (residuals, tank mixes, etc.)

B. Hand weeding

C. Selective applicators

D. Control before, during, and after crop

E. Timeliness is still key

F. Overall objective is to eliminate seed production

Relying Too Heavily on Herbicides??

How long will Liberty last?

How long will residual of Reflex and Valor last?

2013-2015: Develop better programs reducing selection pressure on ALL herbicides

Using Heavy Rye Covers For Sustainability

Rye Cover Weedy Cover

Herbicide Resistance: Will You Survive?

If resistance is one in a billion then you

only need 918 acres to find that plant.

(historically resistance is 1 plant in population of 1-10 million…9.18 acres)

25 plants per square foot emerge = 1,089,000 plants

per acre

Questions/Comments

Heavy Rye Production System: www.farmprogress.com/heavycover