Weed Science Research/Instruction
Post-Tenure Review
William K. Vencill
Department of Crop & Soil Sciences
University of Georgia
Athens, GA
Background
• Appointment (55% Research, 45%
Instruction)
• Research Areas
– Herbicide Resistance
– Herbicide Physiology
– Herbicide Soil Interactions
– Weed Management Systems in HerbicideTolerant Crops
Research – Herbicide Resistance
100
% of cultivated land
80
Soybean
Cotton
Maize
60
40
20
0
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Year
S.O. Duke: WSSA – Feb., 2011, Portland, OR
Total Acres Exposed to Herbicide Sites of
Action for Corn, Soybean, Cotton
140,000
Acres x 103
120,000
100,000
80,000
60,000
40,000
20,000
0
1990
1992
1994
1996
1998
2000
2002
2004
2006
DNA
NASS, 2007
Acetanilides
Glyphosate
Triazines
From Gerwick, Sept., 2010, Agrow
S.O. Duke; WSSA – Feb., 2011, Portland, OR
Counties with GlyphosateResistant Amaranth
200
150
100
50
0
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?
EPSPS Activity in Palmer F2 Plants
EPSPS Relative Copy Number and IC50
54 copies, 22 µM
EPSPS Activity
M Pi / g TSP / min
0.25
54, 22 M
1, 67 M
7.5, 42 M
39, 13 M
0.20
0.15
39 copies, 13 µM
0.10
7.5 copies, 42 µM
0.05
1 copy, 67 µM
0.00
0.1
PNAS, 2010
1
10
100
Glyphosate (M)
1000
10000
9
Other resistance research
•
•
•
•
Triazine-Resistant Palmer
Dinitroaniline-Resistant Palmer
Multiple-Resistant Palmer
ACCase-Resistant Large Crabgrass and
Ryegrass
Triazine Resistant Palmer
Amaranth
0
100
1000
Atrazine (g/ha)
5000
10000
Atrazine Metabolism
1400
1200
dpm
1000
800
Susc
600
Resis
Std
400
200
0
0
1
2
3
4
5
cm
6
7
8
9
Weeds with Resistance to More
than one Mechanism of Action
3
4
1996
50
45
40
35
30
25
20
15
10
5
2008
2006
2004
2002
2000
1998
1992
1990
1988
1986
1984
0
1982
Source:
www.weedscience.org, Ian
Heap, March 2011
2
# Species with Multiple Resistance
The number of weed
species with resistance to
more than one herbicide
mechanism of action has
increased drastically
since 1990. Currently, 50
weed species with
multiple forms of
resistance have been
confirmed.
1994
Resistance Mechanisms
R – Non-target
R – ALS Trp 574 -> Asp
R – ALS Ser 653 -> Asp
R – ALS Ala 122 -> Trp
Susceptible
ALS-Resistant Palmer Amaranth
ALA122
2%
TRP574
16%
SER653
12%
NTR
70%
ALS Resistance
• What are the mechanisms of the non-target
site resistance?
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?
Proposed Resistance Risk Classification
High – ALS,
ACC, PS II-T
Med – EPSP,
Auxin, DNA, PS
I, PDS
Low – VLCFA,
GS
a Integrated
3
2
1
3
6
9
1 (High)
Single Herbicide MOA
1.5
3.0
4.5
0.5 (Mod. – Low)
MOA Rotation Only
0.75
1.5
2.25
0.25 (Low)
Integrated Pest
Mgmta
2
4
6
1 (High)
Single Herbicide MOA
1
2
3.0
0.5 (Mod. – Low)
MOA Rotation Only
0.5
1
1.5
0.25 (Low)
Integrated Pest
Mgmt
0.5
1
3.0
1 (High)
Single Herbicide MOA
0.25
0.5
1.5
0.5 (Mod. – Low)
MOA Rotation Only
0.125
0.25
0.75
0.25 (Low)
Integrated Pest
Mgmt
1
2
3
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
Pest Mgmt refers to use of all weed control tools available such as crop rotation, tillage,
preventative practices, etc.
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
30 %
Photosystem II
Cotoran, Diuron
5%
PPO
Valor, Reflex
3%
Auxin Analogs
2,4-D, Clarity (dicamba)
1%
Glufosinate
Liberty (Ignite)
<1%
Other projects
• New herbicide for other
crops
–
–
–
–
–
Pearl millet
Sunflower
Sweet sorghum
Canola
Stevia
APHIS – WSSA Publications
• .
APHIS contracted with WSSA to have a
state of the art paper written on herbicideresistance
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
Weed Science Editor
Editor since 2009
~200 manuscripts/year
Reduced time from submission to
first response from 62 d to 45 d
Teaching
Teaching
• Weed Science – CRSS
4340/6340
• Weed Science Lab – CRSS
4340L/6340L
• Herbicide Physiology – CRSS
8330-8330L
• Team teach
– Pesticide Use –
CRSS(ENTO)(PATH)4250
– Integrated Pest Mgmt –
ENTO(CRSS) 4740/6740
– Chemical Toxicology – PHRM
8930
• First Year Odyssey Seminar
Instruction-Related Accomplishments
• Undergraduate Coordinator (since 1997)
• College Curriculum (since 2000)
Chair – 2007 and 2011
• University Curriculum (2000-2007)
– 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 (2012-2015)
Awards & Honors
• 2011 D.W. Brooks Faculty Award for Excellence
in Teaching
• 2012 – Senior Teaching Fellow
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
Administrative Duties
http://www.uga.edu/effectiveness/sp.html
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
Any Questions?