Giant ragweed (Ambrosia trifida L.)

106 Pages·2016·0.79 MB·English

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Doctoral Dissertations Graduate School
12-2012
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Kelly Anna Barnett
[email protected]
Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss
Part of the Agriculture Commons
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Barnett, Kelly Anna, "Giant ragweed (Ambrosia trifida L.) biology, competition, and control in cotton
(Gossypium hirsutum L.). " PhD diss., University of Tennessee, 2012.
https://trace.tennessee.edu/utk_graddiss/1508
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To the Graduate Council:
I am submitting herewith a dissertation written by Kelly Anna Barnett entitled "Giant ragweed
(Ambrosia trifida L.) biology, competition, and control in cotton (Gossypium hirsutum L.)." I have
examined the final electronic copy of this dissertation for form and content and recommend
that it be accepted in partial fulfillment of the requirements for the degree of Doctor of
Philosophy, with a major in Plants, Soils, and Insects.
Lawrence E. Steckel, Major Professor
We have read this dissertation and recommend its acceptance:
Christopher L. Main, Thomas C. Mueller, Scott D. Stewart
Accepted for the Council:
Carolyn R. Hodges
Vice Provost and Dean of the Graduate School
(Original signatures are on file with official student records.)
Giant ragweed (Ambrosia trifida L.) biology, competition, and control in cotton (Gossypium
hirsutum L.)

A Dissertation
Presented for the
Doctor of Philosophy
Degree
The University of Tennessee

Kelly Anna Barnett
December 2012
Dedication
This dissertation is dedicated in memory of my father, Barry Barnett.

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Acknowledgements
God has blessed me with so many people that have helped me during my time here at the
University of Tennessee. I would like to thank Dr. Larry Steckel for giving me the opportunity
to pursue a Ph. D. in his program, for his guidance along the way, and willingness to help me
become the best weed scientist I can be. I also want to thank my other committee members, Dr.
Thomas Mueller, Dr. Christopher Main, and Dr. Scott Stewart, for their guidance and support.
You all have been fundamental to my successful completion of this Ph. D.
I also would like to thank all of the folks at WTREC that helped me complete my
research. I wish to thank our station director, Dr. Bob Hayes, as well as Patricia Brawley and
Ernest Merriweather for their technical support. I also can’t thank Sandy Steckel enough for all
of her help with my research, as well as her friendship and hospitality. I would also like to thank
the weed science graduate and undergraduate students, all of whom have spent numerous hours
helping me complete my research. Shawn Butler, Brian Kozlowski, Corey Lonon, Adam
Rushing, Brock Waggoner, and Matthew Wiggins, it has been a pleasure working with you all.
More importantly, I appreciate your friendships and the laughter that each of you brought to my
days in west Tennessee. In addition, I appreciate the friendships of Adam Duncan, Tyler
Simmons, Benjamin and Suzannah Wiggins, and Daniel Wiggins. You all have been such a
blessing to me and made my time here, most enjoyable.
Last but not least, I would like to thank my Mom, Josh, Kaicy, Nate, Megan, Leslie,
Mimi and Papaw, and additional family and friends for their love and support during my many
years of graduate school. And to my daddy, for teaching me about hard work, perseverance, and
a thing or two about weed control. I love you and miss you.
I have fought the good fight, I have finished the race, I have kept the faith. 2 Timothy 4:7
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Abstract
The objectives of this research were to evaluate control options and investigate the
biology and competitiveness of glyphosate-resistant (GR) giant ragweed in cotton. Our results
determined that glufosinate followed by glufosinate, glufosinate plus pyrithiobac, and glufosinate
plus fluometuron at 0.56 or 1.12 kg ai ha-1 resulted in the highest level of visual control and the
highest yield. However, glufosinate followed by glufosinate was the only treatment that resulted
in the highest yield and > 90% control of GR giant ragweed.
The development of glufosinate-tolerant, 2,4-D tolerant, and dicamba-tolerant crops may
provide growers with new opportunities for difficult-to-control weeds such as GR giant ragweed.
Therefore, the next objective of this research was to evaluate control options for GR giant
ragweed with 2,4-D and dicamba applied alone and in combination with glufosinate or
fomesafen. Results determined that tank-mix combinations with glufosinate or fomesafen that
included either 2,4-D or dicamba resulted in a higher level of control of GR giant ragweed than
2,4-D or dicamba applied alone. Tank-mixing 2,4-D or dicamba with glufosinate will be a
valuable approach for controlling GR giant ragweed.
The final objective was to conduct a study to determine competition of giant ragweed in
cotton. Early in the growing season, treatments with 2400 or more giant ragweed plants per ha-1
reduced cotton height when compared with the competition free control. A delay in cotton
maturity was observed only with higher populations of 4800 or 9600 plants. However, the effect
of giant ragweed on yield was evident with the lowest population of 600 giant ragweed plants per
ha-1 reducing lint yields by 300 kg ha-1 when compared with a competition free control. Cotton
fiber quality was not affected by giant ragweed. These results indicate that season-long giant
ragweed competition can significantly reduce cotton yields.
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Table of Contents

Part I.

Introduction ..........................................................................................................1

Literature Cited ........................................................................................12

Part II. Glyphosate-Resistant Giant Ragweed (Ambrosia trifida L.) Control in
WideStrike® Flex Cotton ..............................................................................................19

Abstract ................................................................................................................20

Nomenclature ...........................................................................................20

Keywords .................................................................................................20

Introduction ..........................................................................................................20

Materials and Methods .........................................................................................24

Results and Discussion ........................................................................................26

Cotton injury ............................................................................................26

GR giant ragweed control ........................................................................27

Giant ragweed counts and biomass ..........................................................29

Effect of herbicide applications on yield .................................................29

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Literature cited .....................................................................................................32

Part III. Glyphosate-Resistant Giant Ragweed (Ambrosia trifida L.) Control with Non-
Glyphosate Weed Control Technologies .....................................................................37

Abstract ................................................................................................................38

Nomenclature ...........................................................................................38

Keywords .................................................................................................38

Introduction ..........................................................................................................39

Materials and Methods .........................................................................................42

Results and Discussion ........................................................................................43

Giant ragweed control ..............................................................................43

Giant ragweed populations ......................................................................45

Giant ragweed biomass ............................................................................46

Literature cited .....................................................................................................49

Part IV. Giant Ragweed (Ambrosia trifida L.) Competition in Cotton (Gossypium
Hirsutum L.)....................................................................................................................52

Abstract ................................................................................................................53

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Nomenclature ...........................................................................................54

Keywords .................................................................................................54

Introduction ..........................................................................................................54

Materials and Methods .........................................................................................57

Results and Discussion ........................................................................................60

Cotton height ............................................................................................60

Node above white flower .........................................................................62

Node above cracked boll ..........................................................................62

Giant ragweed biomass ............................................................................62

Effect of giant ragweed competition on cotton lint yield ........................63

Effect of giant ragweed competition on cotton fiber quality ...................64

Literature cited .....................................................................................................67

Conclusions ..........................................................................................................71

Part I .........................................................................................................71

Part II .......................................................................................................72

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Part III ......................................................................................................72

Appendices ...........................................................................................................74

Appendix A

Tables .......................................................................................................75

Appendix B

Figures......................................................................................................91

Vita .......................................................................................................................94

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