1. Weed Science Research/Instruction Post-Tenure Review
William K. Vencill
Department of Crop & Soil Sciences
University of Georgia
Athens, GA

2. Background Appointment (55% Research, 45% Instruction) Research Areas
Herbicide Resistance
Herbicide Physiology
Herbicide Soil Interactions
Weed Management Systems in Herbicide-Tolerant Crops

3. Research – Herbicide Resistance

4. S.O. Duke: WSSA – Feb., 2011, Portland, OR

5. Total Acres Exposed to Herbicide Sites of Action for Corn, Soybean, Cotton
NASS, 2007

6. From Gerwick, Sept., 2010, Agrow
S.O. Duke; WSSA – Feb., 2011, Portland, OR

7. Counties with Glyphosate-Resistant Amaranth

8. Glyphosate Resistance
Target site resistance
Vacuolar sequestration
Overexpression EPSP target site
Does this occur in all glyphosate-resistant Palmer amaranth populations?
Do multiple mechanisms occur in some populations?

9. EPSPS Activity in Palmer F2 Plants
54 copies, 22 µM
39 copies, 13 µM
7.5 copies, 42 µM
1 copy, 67 µM
PNAS, 2010

10. Other resistance research
Triazine-Resistant Palmer
Dinitroaniline-Resistant Palmer
Multiple-Resistant Palmer
ACCase-Resistant Large Crabgrass and Ryegrass

11. Triazine Resistant Palmer Amaranth
Atrazine (g/ha)

12. Atrazine Metabolism

13. Weeds with Resistance to More than one Mechanism of Action
The number of weed species with resistance to more than one herbicide mechanism of action has increased drastically since Currently, 50 weed species with multiple forms of resistance have been confirmed.
Source: Ian Heap, March 2011

14. R – Non-target
R – ALS Trp 574 -> Asp
R – ALS Ser 653 -> Asp
R – ALS Ala 122 -> Trp
Susceptible

15. ALS-Resistant Palmer Amaranth

16. ALS Resistance
What are the mechanisms of the non-target site resistance?

17. Questions about Herbicide Resistance
Why are some weeds more prone to developing resistance than others?
Why have some weeds never developed resistance even with intensive pressure?
Why are some herbicide MOA more prone to resistance development than others?

18. Proposed Resistance Risk Classification
High – ALS, ACC, PS II-T 3 6 9
1 (High)
Single Herbicide MOA
1.5
3.0
4.5
0.5 (Mod. – Low)
MOA Rotation Only
0.75
2.25
0.25 (Low)
Integrated Pest Mgmta
Med – EPSP, Auxin, DNA, PS I, PDS 2 4 1
0.5
Integrated Pest Mgmt
Low – VLCFA, GS
0.25
0.125
ELEIN, Senecio, SOLXX, Salsola, Poa, DIGXX
Avena, ECHCG, XANST, SORHA, SETXX,
AMAXX, AMBXX, LOLXX, KOCXX, CHEAL, Conyza
Blue – Highest Risk
Orange – Higher Risk
Yellow – Moderate Risk
Green – Low Risk
a Integrated Pest Mgmt refers to use of all weed control tools available such as crop rotation, tillage, preventative practices, etc.

19. Herbicide-Resistant Weeds Loss of Options
Herbicide MOAs
Trade Name
Est. Loss of Efficacy
ALS (in soybeans)
Pursuit, Staple
95 %
ALS (in cotton)
Staple
60 %
ACCase
Assure, Fusilade
30 %
Glycine
Roundup and others
Photosystem II
Cotoran, Diuron
5 %
PPO
Valor, Reflex
3 %
Auxin Analogs
2,4-D, Clarity (dicamba)
1 %
Glufosinate
Liberty (Ignite)
< 1 %
slide 2) critical mechanisms of action and loss of utility
ALS (Staple) %loss 67%
ACCase (Select) %40
Glycine (RoundUp) %35
Glufosinate (Ignite) %1
PPO (Valor, Reflex) %5
PS2 (Cotoran, Diuron) %10
Phenoxy (2,4-D) %1
ALS in Soybeans %100

20. Other projects New herbicide for other crops Pearl millet Sunflower
Sweet sorghum
Canola
Stevia

21. APHIS – WSSA Publications.
APHIS contracted with WSSA to have a state of the art paper written on herbicide-resistance
Second project contracted with APHIS to write a paper on recommendations
Both papers served as foundation for National Academy of Sciences Summit on Strategies to Manage Herbicide-Resistant Weeds

22. Weed Science Editor Editor since 2009 ~200 manuscripts/year
Reduced time from submission to first response from 62 d to 45 d

23. Teaching

24. Teaching Weed Science – CRSS 4340/6340
Weed Science Lab – CRSS 4340L/6340L
Herbicide Physiology – CRSS L
Team teach
Pesticide Use – CRSS(ENTO)(PATH)4250
Integrated Pest Mgmt – ENTO(CRSS) 4740/6740
Chemical Toxicology – PHRM 8930
First Year Odyssey Seminar

25. Instruction-Related Accomplishments
Undergraduate Coordinator (since 1997)
College Curriculum (since 2000)
Chair – 2007 and 2011
University Curriculum ( )
General Education (2002-present)
Board of Regents Committee to reform Core Curriculum (2008)
Board of Regents Council of General Education (since 2010)
ConnectUGA Project Advisory Team ( )

26. Awards & Honors
2011 D.W. Brooks Faculty Award for Excellence in Teaching
2012 – Senior Teaching Fellow

27. Teaching – Graduate Students
In the past five years, have mentored six graduate students on a thesis program; four on a non-thesis program.
Serve as the Crop & Soil Science representative on the Master of Plant Protection Pest Management Program
On all student’s committees
Proctor an exit written exam on weed science

28. Administrative Duties

30. Other Administrative Duties
Supervised Office of Faculty Affairs
Promotion and tenure committees
Workshops for faculty
University Program Review
University System Ethics Policy Committee
Budget Review
SACS Leadership & Compliance

31. Any Questions?