1. Script
This slideset is to help farmers be able to identify
and effectively control Palmer pigweed. It is
resistant to glyphosate, so we are having to find
alternative methods of control. The following
will walk you through the process of Need,
Identification, and Control.

2. Palmer Pigweed
Amaranthus palmeri

3. History of Palmer Amaranth
• Found in Lauderdale County, TN in 2006
• Across West TN in 2008
• Couldn’t kill certain Pigweeds in Fulton County
in 2008
• Confirmed Resistance in 2009 in Fulton
County
• Outbreak in 2010
• Began Intense Focus in 2011

4. Enter question text...
Can You Identify These Pigweeds?
1 2 3
1. Photo 1
2. Photo 3
3. Photo 2
33% 33% 33%
1
3
2
o
o
o
ot
ot
ot
Ph
Ph
Ph

5. Smooth Palmer
Waterhemp
Pigweed Amaranth

6. Palmer Amaranth
Bradley Missouri

7. Waterhemp Short Flowering Palmer Long
Branches Flowering
Branches

8. Lauderdale County 2008
152 oz/A Roundup PowerMax
Steckel 2008

9. 22 fb 22 ozs/A Roundup PM on 1-3” then 6-8” Palmer
Steckel 2009

10. 2 WAA of 40 oz/a of Gly 4

13. Just Gave Up!
Steckel 2009

14. Taproot of
A. Palmeri
Allen 2009

16. Waterhemp & Palmer Amaranth Distribution in KY
(Co. Agent Survey 2010)
Waterhemp Palmer Amaranth Waterhemp &
Palmer Amaranth
Last Updated 11-23-2010

17. Waterhemp & Palmer Amaranth Distribution in KY
(Co. Agent Survey 2011)
Waterhemp Palmer Amaranth Waterhemp &
Palmer Amaranth
Last Updated 12-5-11

18. Soil-Residual Herbicides For Palmer Amaranth
Soil Residual Herbicide Site of Activity P.Amaranth
Authority Assist PPO + ALS ─
Authority First / Sonic PPO + ALS X
Authority MTZ PPO + PS II X
Boundary PS II + Cell Div . X
Envive PPO +ALS + ALS X
Gangster PPO + ALS ─
Prefix PPO + Cell Div. X
Spartan Charge PPO + PPO ─
Treflan Microtubule X
Valor SX PPO X
Valor XLT PPO & ALS X

19. Postemergence Soybean Herbicides for
Waterhemp & Palmer Amaranth
Post Site of Activity P. Amaranth
Herbicide
Ultra Blazer PPO ─
Cobra PPO ─
Flexstar PPO X
Flexstar GT PPO + EPSP X
Glutamine
Ignite X
Synthetase

20. KIH 485 (pyroxasulfone)
Initial Discovery & MARKETING IN US
Development (2012 ?)
• BASF (Zidua)
• KUMIAI Chemical
Industry Co, Ltd
• FMC (Anthem)
• IHARA Chemical
Industry Co.,Ltd
• VALENT (Fierce)

21. PYROXASULFONE HERBICIDES
HERBICIDE
ACTIVE INGREDIENTS
PRODUCT
Pyroxasulfone
ZIDUA
Pyroxasulfone +
ANTHEM Fluthiacet (Cadet)
Pyroxasulfone +
FIERCE
Flumioxazin (Valor)
(For Corn & Soybean 2012?)

22. EVALUATION OF PREEMERGENCE HERBICIDES FOR
PALMER AMARANTH CONTROL (Major’s farm) – 2011)

23. ANTHEM 8 oz/A
Photo 10-04-11 (Approx 10 WAT)

24. Fierce 3.75 oz/A
Photo 10-04-11 (Approx 10 WAT)

25. Zidua 2.5 oz/A
Photo 10-04-11 (Approx 10 WAT)

26. Preemergence Control of Palmer Amaranth
(Fulton Co 2011)
HERBICIDE RATE % Control
Anthem 8 oz/A 100
Fierce 3.75 oz/A 100
Zidua 2.5 oz/A 98
Applied: 7-27-2011 Rated: 10-04-2011

27. Preemergence Control of Palmer Amaranth
(Fulton Co 2011)
HERBICIDE RATE % Control
Anthem 8 oz/A 100
Fierce 3.75 oz/A 100
Zidua 2.5 oz/A 98
Dual II Magnum 1.67 pt/A 70
Warrant 1.7 pt/A 60
Boundary 3 pt/A 100
Applied: 7-27-2011 Rated: 10-04-2011

28. Preemergence Control of Palmer Amaranth
(Fulton Co 2011)
HERBICIDE RATE % Control
Anthem 8 oz/A 100
Fierce 3.75 oz/A 100
Zidua 2.5 oz/A 98
Authority First 6.45 oz/A 100
Authority MTZ 18 oz/A 98
Authority XL 7.5 oz/A 98
Applied: 7-27-2011 Rated: 10-04-2011

29. Preemergence Control of Palmer Amaranth
(Fulton Co 2011)
HERBICIDE RATE % Control
Anthem 8 oz/A 100
Fierce 3.75 oz/A 100
Zidua 2.5 oz/A 98
Prefix 2.75 pt/A 100
Spartan 8 OZ/A 100
Valor 2.5 oz/A 100
Applied: 7-27-2011 Rated: 10-04-2011

30. GR Pigweed Summary
• Pre Emergence Options
• Boundary (1.5 pts)
• Envive (2.5 ozs)
• Prefix (1 qts)
• Valor (3 ozs)
• Authority MTZ (18 ozs)
• Valor XLT ( 3 ozs)

31. GR Pigweed Summary
• Post Options:
• 1 to 3” Palmer amaranth
• Flexstar (1.5 pts)
• Cobra (12 ozs)
• Blazer (1.5 pts)

32. Pre Partially Activated and Post a Few Days Late
Steckel 2010

33. Pre Washed Away and Post a Few Days Late
Steckel 2010

34. The Difference of 2 Days!
Flexstar on 6” Palmer Flexstar on 3” Palmer
Steckel 2010

35. What about Ignite?
• Ignite (glufosinate) is a viable alternative
• Needs to be applied during middle of the day
• Use minimum of 15 gallons of water
• New for this year –
– Sequential Application
– 22-36 oz fb 22-29 oz

36. 29oz Ignite @ 10gal

37. Same Weed – 3 WAA

38. Timing is
CRITICAL!!!

39. PPO’s Ignite
• 1-3 tall Palmer • 1-6 tall Palmer
• Multiple applications • MUST USE 15gal/Ac!
may be necessary • Try to apply in the
• Sequential applications middle of the day
prohibited • Can use sequential
application

40. Glyphosate-Resistant Weeds
Southern United States
Conyza canadensis (marestail)
Amaranthus palmeri (Palmer amaranth)
Ambrosia trifida (giant ragweed)
Ambrosia artemisiifolia (common ragweed)
Amaranthus tuberculatus (common waterhemp)
Lolium multiflorum (Italian ryegrass)
Sorghum halepense (Johnsongrass)
Eleusine indica (Goosegrass)
Poa annua (annual bluegrass)

41. Questions?
Cam Kenimer
Fulton County Extension Service
2114 South 7th
Hickman, KY 42050
270-236-2351
www.ca.uky.edu/fulton