herbicide-resistant weeds: a dilemma in dixie culpepper, york, steckel, prostko
TRANSCRIPT
Herbicide-Resistant Weeds:A Dilemma in Dixie
Culpepper, York, Steckel, Prostko
What is Herbicide Resistance? (official WSSA definition)
Inherited ability of a biotype of a weed
to survive and reproduce following
exposure to a dose of herbicide
normally lethal to the wild type.
WeatherMax 22 oz, 2 d after application to 16 inch Palmer
WeatherMax 33 oz/A on 3” Palmer
0
50
100
150
200
250
300
350
1955 1970 1985 2000
Nu
mb
er
of
case
sReported cases of herbicide-resistant weeds in US
Why is Resistance Such a Big Deal Now?
Why is Resistance Such a Big Deal Now?
1. ALS resistant pigweeds2. Glyphosate-resistant horseweed3. Glyphosate-resistant ragweed4. Glyphosate-resistant lambsquarters*5. Glyphosate-resistant Italian ryegrass*
1. Glyphosate-resistant Palmer amaranth (pigweed)
Significant
Potentially Devastating
*suspected not confirmed
9794
00
ALS*-resistant Amaranthus species
*Imidazolinones, sulfonylureas, 19 states
triazolopyrimidines, pyrimidinylthiobenzoates
94
02
94 95
00
9298
99 029398
9693
93
91
99
Commonly Used ALS Herbicides
• Accent• Ally/Cimarron• Beacon• Beyond• Cadre • Classic• Envoke• Exceed• Express • Finesse• FirstRate
• Glean• Harmony Extra• Maverick Pro• Osprey • Peak• Permit• Pursuit• Python• Scepter• Staple• Strongarm
Prostko 2006
2005 ALS-Resistant Pigweed Survey61 locations, 21 counties
• 2892 plants treated• 2442 plants survived (84%)
100
66
97
99
98
98
98
99
99
100
98
9883 9775
97
59
Percent of cotton acreage planted to RR varieties. 20061
1USDA, AMS. 2006. Publ. mp-cn833.
0
10
20
30
40
0
2
4
6
8
10
12
0
10
20
30
40
50
60
70
80
96 97 98 99 00 01 02 03 04 05 06
98 99 00 01 02 03 04 05 0697 98 99 00 01 02 03 04 05 06
Adoption of Roundup Ready
Technology in the US
(million acres)
Soybean
CornCotton
Very Small
Seeded
Approximately 1 mm
Shields, E.J., J.T. Dauer, M.J. VanGessel, and G. Neuman. 2006. Horseweed (Conyza canadensis) seed collected in the planetary boundary layer. Weed Sci. 54:1063-1067.
Altitude
(ft)
230
460
Seeds found
(#/1000 m3)*
3.3
1.7
* Approximately 33 by 33 by 33 ft
Photo credit: Larry SteckelPhoto credit: Larry Steckel
Must Start Clean!Must Start Clean!
Photo credit: Larry SteckelPhoto credit: Larry Steckel
GR Horseweed Control
0 20 40 60 80 100
Roundup WM 22oz
Clarity 8 oz + Roundup WM 22oz
Ignite 23 oz
LSD = 12
% Horseweed Control
Milan May 28, 2006
2,4-D 16 oz + Roundup WM 22oz
Burndown applied 4/3/06
Clarity 8 oz + Roundup WM 22oz fb/Gramoxone Inteon 40 oz + Caparol 24oz
Clarity 8 oz + Roundup WM 22oz fb/Roundup WM 22oz + Cotoran 24oz
HORSEWEED Preferred Burndown Options
1. Roundup + ½ pt Clarity, mid March
2. Roundup + 2 pt 2,4-D, mid March
With either of above, consider a residual herbicide with the burndown, such as Valor.
If no residual, Gramoxone + Cotoran or Direx at planting or Ignite + Cotoran or Direx
at planting.
2004 Common Horseweed Burndown Program
Photo credit: Larry SteckelPhoto credit: Larry Steckel
Rapid Growth Becoming Extremely Large
Average Number of Seed Produced per PlantAverage Number of Seed Produced per Plant
400,000
40,000 40,000 9,0000
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
PalmerAmaranth
goosegrass annualbluegrass
commoncocklebur
Top 4 Herbicide Resistant Weeds in US peanut - 175; cotton - 250; corn - 800
Attapulgus GA, September 2004
Multiple Generations – Short Seed Dormancy
Untreated
Georgia, 2006
Glyphosate 4X rate,
applied three times
Palmer Amaranth Infesting Cotton
North Carolina, 2006
Untreated Glyphosate 4X rate,
applied three times
Palmer Amaranth Infesting Cotton
Cotton Yield vs. Palmer Competition
0
500
1000
1500
2000
2500
0 1 2 3 4 5 6 7 8 9 10
Palmer Density (num/20ft)
See
d C
ott
on
Yie
ld (
lbs/
A)
7%
Glyphosate-resistant Palmer Amaranth Found
04
05
***
*Palmer populations being studied for resistance.
Resistance trait will move through pollen
Managing Glyphosate Resistance
Georgia and North Carolina Recommendations*
At Planting
Topical (1-to 4 lf cotton) Layby Directed
Yellow
+
Reflex
Glyphosate + Dual Magnum
(no emerged Palmer)MSMA + Diuron
MSMA + Layby Pro
MSMA + Suprend
MSMA + ValorGlyphosate + Staple
(Palmer 1-2”)
*Cultivation, Hooded Sprays, and/or Hand Weeding Will be Required
Prowl H20 1.75 pt + Reflex 1 pt PRE
WeatherMax 22 oz + Dual Mag 18 DAP before Pigweed emergence
WeatherMax 22 oz + Direx 1.5 pt PDIR
Prowl H20 1.75 pt + Reflex 1 pt PRE
WeatherMax 22 oz + Dual Mag 24 DAP with ½” Palmer
WeatherMax 22 oz + Direx 1.5 pt PDIR
Prowl + Reflex PRE
Roundup + Staple 3 inch
Direx + MSMA PD
Prowl H20 1.75 pt + Reflex 1 pt PRE
WeatherMax 22 oz + Staple at 3 inch
WeatherMax 22 oz + Direx 1.5 pt PDIR
0 1.3 5.2 10.2 20.42.6Staple LX fl oz/A
2004
2006
1X glyphosate + 1X Staple; Palmer 0.5 inches when treated
Delay the arrival or spread of resistance
Resistance Management Practices
1. Reduce herbicide reliance (as practical)
2. Diversify MOAs; Multiple MOAs
a. Multiple MOAs within a crop.
At Planting Topical (1-to 4-lf cotton) Layby Directed
Yellow
Glyphosate
+
Dual Magnum or Staple
MSMA or glyphosate
+
Diuron,
Layby Pro,
Suprend, or
Valor
*Staple will not control ALS-resistant Palmer. Sequence can be used as the glyphosate + Dual mixture. Yellow = Prowl or Treflan type products.
DELAY glyphosate-resistant Palmer in RR cotton fields with LIGHT Palmer infestations*
Resistance Management Practices
1. Reduce herbicide reliance (as practical)
2. Diversify MOAs; Multiple MOAs
a. Multiple MOAs within a crop.
b. Crop rotation; different MOAs
Resistance Management Practices
1. Reduce herbicide reliance (as practical)
2. Diversify MOAs; Multiple MOAs
a. Multiple MOAs within a crop.
b. Crop rotation; different MOAs
3. Detect resistance early
Glyphosate-resistant Palmer amaranth: Georgia, 2005
Detect Resistance Early
More on glyphosate-resistant Palmer?
From 1:30 till 2:45 in Grand Ballroom C
- distribution, pollen dispersal, and management
How Bad Will Glyphosate-Resistant Palmer Amaranth Become?
“This Palmer amaranth stuff makes me glad I am 18 months from retirement.”
Dr. Alan York
• Weed Resistance Learning Module at National Cotton Council Web Site: http://www.cotton.org/
• International Survey of Resistant Weeds
* http://www.weedscience.org/in.asp
• Cotton Incorporated is nearing completion of a Resistance Management Bulletin
Knowledge Gives Us Hope