Crop Management Seminar Introduction Weed …...2017/03/17  · Crop Management Seminar Introduction Weed Management Author Dr. Robert L. Nichols Keywords Crop Management Seminar Introduction

Cotton IncorporatedCotton Incorporated Crop Management Seminar

Introduction to the SessionIntroduction to the Session

Weed Management Robert Nichols

Cotton Incorporated

Predominant IssuesPredominant Issues Glyphosate Resistanceyp

• Management of Glyphosate-Resistant Palmer AmaranthPalmer Amaranth

• Management of Glyphosate-Resistant RyegrassRyegrass

• Containing Glyphosate-Resistant JohnsongrassJohnsongrass

• Future Cotton and Soybean Weed Management

Definition: Weed ResistanceWeed Resistance

“Inherited ability of a weed population y p pto survive and reproduce after exposure to an herbicide dose (rate) p ( )that would control an unselected population”

--- Weed Science Society of America

90 ACCase InhibitorsALS Inhibitors

70

80

cies

.

TriazinesBypyridiliumsSynthetic Auxins

50

60

tant

Spe

c Glycines

30

40

r of R

esis

10

20

30

Num

ber

0

10

0 5 10 15 20 25 30 35 40 45 50 55 600 5 10 15 20 25 30 35 40 45 50 55 60

Years of Usage

Acetolactate Synthase Resistant Palmer Amaranth

99*

93

99 02

9698 93

0094

9293

9495

9700

92

9402

* Year of 1st

reportp

Glyphosate-Resistant Crop Acres ( illi )(millions)

120

80

100

60

80

illio

n A

cres

40

M

0

20

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 20061996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Cotton Corn Soybean

Percent of Glyphosate-Resistant Cotton Cultivars

9799

989910059

100

66

99

989899 98

9883

9775

99

USDA, AMS. 2006.

Total Acres Exposed to Herbicide Modes of Action f C S b C ttfor Corn, Soybean, Cotton

140,000

60,000

80,000

100,000

120,000

Acr

es x

103

0

20,000

40,000

19901992

19941996

A

19961998

20002002

20042006

DNA Acetanilides Glyphosate TriazinesDNA Acetanilides Glyphosate Triazines

Number of Glyphosate-Resistant Species

20

14

16

18

8

10

12

Cou

nt

4

6

8

0

2

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

YearsYears

Palmer Amaranth(Amaranthus palmeri)(Amaranthus palmeri)

A dioecious annual weed,

growinggrowing 4-8 feet tall,producing

up to 500,000seed per year

Impacts of Glyphosate-ResistantImpacts of Glyphosate Resistant Palmer Amaranth

• Increased complexity and costs of weed management in cotton andweed management in cotton and soybeanC• Compromising conservation tillage

• May precipitate a cascade of resistance in post emergence broad-leaf herbicides

Glyphosate-Resistant Palmer AmaranthGlyphosate Resistant Palmer AmaranthEconomic Threat to Soybeans

If ALS d l h t i d PPOIf ALS and glyphosate are compromised, PPO herbicides are the only post emergence option except glufosinatep g

Economic Threat to Cotton If ALS herbicides and glyphosate are compromised; PPO herbicides are not an over-the-top option, there are no selective post emergence options for cotton except glufosinate