2014: Herbicide Resistance Changes Agriculture Forever Stanley Culpepper Tifton, 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 Source: International Survey of Herbicide Resistant Weeds (10/4/12) CT-2 DE-7 HI- 4 MD-11 MA-2 NH-2 NJ-4 RI-1 VT

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 acreage 2. Few or no alternative classes of chemistry used 3. Little to no tillage 4. Little to no rotation in crops 5. Often in stressful environments when herbicide activity is minimized 6. 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

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 inches 52 hr

Picture taken 7 am on /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?

230 K 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 HorseweedWaterhempPalmer amaranth

Palmer amaranth seed production allows for rapid field domination Year 1Year 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 lb ai/A : Herbicide costs = $27.80/A : Herbicide costs = $68.00/A

Changes in Herbicide Management 2002: $24/A2010: $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 : 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 cultivated 2010: 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* *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?

: Develop better programs reducing selection pressure on ALL herbicides

Using Heavy Rye Covers For Sustainability Rye CoverWeedy 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: