Future Citrus Herbicide Developments
Roundup Comparison Treatment
• Potential changes in glyphosate formulations in Arizona
– Roundup Weathermax, other trade names
Roundup / Roundup Ultramax
• Registration of Prowl for bearing citrus
Weed Control in Lemons
• Potential registration of Chateau
Many morningglory plants are severely injured but survive.
– Flumioxazin, V53482
– Burndown, contact herbicide - broadleaves.
– Has preemergence soil activity
William B. McCloskey
Extension Weed Specialist
Department of Plant Sciences
University of Arizona, Tucson, AZ
• Potential registration of Aim
– Carfentrazone-ethyl
– Burndown, contact herbicide - broadleaves
• Potential registration of Envoke
– Trifloxysulfuron, CGA362622
– Postemergence nutsedge and broadleaf weed control, some
grass suppression
Aim @ 0.016 lb ai/A +1 % COC at 12 in tall cotton
Aim @ 0.016 lb ai/A +1 % COC at 12 in tall cotton
Aim @ 0.016 lb ai/A +1 % COC at 12 in tall cotton
Stem injury
Leaf injury
Cotton injury
ranged
between 0
(comparison
treatment)
and 8%.
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1
Valor @ 0.031 lb ai/A + Roundup @0.75 lb ae/A + AMS
at the 12 in tall growth stage of cotton
• Envoke has also been
investigated as a post-direct
treatment in cotton.
Note leaf injury
• Has significant broadleaf
activity and activity on
nutsedge species unlike Aim or
Chateau.
Materials and Methods
Phytotoxicity after a Single Herbicide
Application
The experiments were conducted on a native population of purple
nutsedge at the Campus Agricultural Center of the University of
Arizona in Tucson, Arizona.
7 July 2001
10
8
The experiments
were conducted
Aug 1999 through
March 2000 and July
2001 through March
2002.
Phytotoxicity
Envoke Applications for Purple Nutsedge Control
Envoke (trifloxysulfuron or CGA362622)
Valor @ 0.031 lb ai/A + Roundup @0.75 lb ae/A + AMS
at the 12 in tall growth stage of cotton
Rates are in g/ha
Untreated
Halosulfuron-35
Halosulfuron-70
Trifloxysulfuron-5
Trifloxysulfuron-15
RoundupUM-840
TouchdownIQ-840
6
4
2
0
0
10
20
30
40
50
60
70
80
90
Days after Treatment
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2
Phytotoxicity after 1 Application of Herbicide
Phytotoxicity of 1 versus 2 herbicide applications
Trifloxysulfuron 15 g/ha
7 July
(Initial Application Date 7 July 2001)
Halosulfuron (70 g/ha)
10
28 September 2001
(75 DAT)
1 application on 7 July
8
Applications on 7 July and 4 Aug
Rates are in g/ha
Phytotoxicity
23 July 2001
(16 DAT)
Phytotoxicity on 28 September 2001
4 Aug
untreated
1 Halosulfuron-70
2 Halosulfuron-70
1 Trifloxysulfuron-15
2 Trifloxysulfuron-15
6
4
2
0
0
10
20
30
40
50
60
70
80
90
Days After Treatment
Phytotoxicity on 28 September 2001
Two Envoke applications @ 15 g/ha
Phytotoxicity after Two Herbicide Applications
7 July
Phytoxicity of 2 vs. 4 applications of Roundup Ultramax
4 Aug
7 July
10
Phytotoxicity
untreated
Halosulfuron-35
Halosulfuron-70
Trifloxysulfuron-5
Trifloxysulfuron-15
RoundupUM-840
TouchdownIQ-840
6
4
2
Phytotoxicity
Rates are in g/ha
8
4 Aug 20 Aug 20 Sep
10
8
Rates are in g/ha
6
untreated
4 RoundupUM-840
2 RoundupUM-840
4
2
0
0
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80 90
Days After Treatment
Days after Treatment
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Phytotoxicity on 28 September 2001
Roundup UltraMax (840 g/ha)
Applications on 7 July and 4 Aug
Envoke @ 0.007 lb ai/A + 0.5% NIS at the 12 in tall
growth stage of cotton
Envoke @ 0.007 lb ai/A + 0.5% NIS at the 12 in tall
growth stage of cotton
Applications on 7 July, 4 Aug,
20 Aug and 20 Sep
Envoke @ 0.007 lb ai/A + Touchdown @ 0.75 lb ae/A at
the 12 in tall growth stage of cotton
Touchdown @ 0.75 lb ae/A at the 12 in tall growth
stage of cotton
Evaluating an Optical Weed Sensing Herbicide Sprayer
and Weed Management in Citrus and Pecans
Ryan J. Rector and Bill McCloskey
(Graduate Student and Extension Specialist)
Department of Plant Sciences
University of Arizona
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4
WeedSeeker Sprayer - Kawasaki 3010 4WD Mule.
WeedSeeker/Kawasaki Mule Sprayer
WeedSeeker/Kawasaki Mule Sprayer
WeedSeeker Sprayer
Kubota/Conventional Sprayer
H1 – WeedSeeker Sprayer, Glyphosate Only
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5
H2 – WeedSeeker Sprayer, PRE + Glyphosate
H3- Conventional Sprayer – Glyphosate Only
Percent of Ground Surface Sprayed – Yuma, AZ
100
H1 – WeedSeeker-POST
H2 – PREE & WeedSeeker
POST
H3 – Conventional POST
Percent of Ground Sprayed
90
80
70
60
10/15/2001
3/4/2002
8/13/2002
11/21/2002
5/20/2003
8/4/2003
50
40
30
20
10
0
Optical Weed Sensing Sprayer/Postemergence
Herbicides – White Wing Citrus, 6/25/03
H1
H2
H3
WeedSeeker Treatments
Conventional Sprayer/Postemergence
Herbicides – White Wing Citrus, 6/25/03
Whitewing Ranch weed
spray map generated in
October 2003 using a
Trimble AgGPS 132 DGPS
receiver (WAAS correction)
and a custom datalogger
from the University of
Tennessee.
Plots in replication 3 were
not mapped due to
technical difficulties.
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6
Percent of Ground Surface Sprayed –
Dateland, AZ
Whitewing Ranch weed
spray map for plots in
replication 3 at the southern
edge of the orchard block.
Percent sprayed is the
percentage of the time the
nozzles were spraying in 1
sec intervals. The sprayer
was traveling at 6 mph or
8.8 ft/s.
FICO – Vegetative Strip in Panel Middles
4 – WeedSeeker – POST
5 – Conventional - POST
90
Percent of Ground Sprayed
The datalogger checked
nozzle valves 300 times per
second to determine when
the nozzles were open and
spraying.
100
White Wing Ranch, Hyder, AZ on August 14,
2003 After 1.5” of Rainfall
80
70
60
50
6/6/2003
6/25/2003
8/27/2003
40
30
20
10
0
WeedSeeker (4)
Conventional (5)
WeedSeeker Treatments
FICO - Conventional Sprayer – 6/26/03
Page 7
FICO-Optical Weed Sensing Sprayer –
6/26/03
7
The datalogger checked
nozzle valves 300 times per
second to determine when
the nozzles were open and
spraying.
Percent sprayed is the
percentage of the time the
nozzles were spraying in 1
sec intervals. The sprayer
was traveling at 6 mph or
8.8 ft/s.
WeedSeeker Area Sprayed versus Groundcover (11/01 - 8/03)
0.40
Evaluating the Optical Weed Sensing Sprayer
Technology – Current Results and Future Plans
• WeedSeeker sprayer optically detects and sprays weeds, not
bare ground
0.35
0.30
• Yuma, AZ - Chemical and spray volume was reduced an
average of 57%, postemerge with WeedSeeker, for six spray
operations during 2001 – 2003 and 65% for the same spray
operations using a preemerge plus the WeedSeeker.
0.25
0.20
• Hyder, AZ – Spray volume has been reduced an average of
85% so far in 2003 using the WeedSeeker sprayer.
0.15
• Sahuarita, AZ – Spray volume has been reduced an average of
34% so far in 2003 using the WeedSeeker sprayer.
0.10
0.05
100
4 – WeedSeeker -POST
3 – Conventional - POST
90
Percent of Ground Sprayed
FICO pecan orchard weed
spray map generated in
September 2003 using a
Trimble AgGPS 132 DGPS
receiver (WAAS correction)
and a custom datalogger
from the University of
Tennessee.
Area Sprayed (A)
Percent of Ground Surface Sprayed –
Sahuarita, AZ
FICO pecan orchard weed
spray maps for plots in
replication 1 and part of
replication 2 at the southern
end of the orchard block.
80
70
60
6/26/2003
7/10/2003
8/6/2003
9/10/2003
50
40
30
20
10
0
WeedSeeker (4)
Conventional (3)
WeedSeeker/Perfecta Treatments
Evaluating the Optical Weed Sensing Sprayer
Technology – Current Results and Future Plans
• Use of GPS and a receiver with GIS to:
– Map postemergence spray applications, superimpose several
application maps and produce a weed density map.
– Spray preemergence herbicide based on the weed map
generated
• Collaboration with the University of Tennessee (Dr. John
Wilkerson) where the data logger was constructed. UT is
assisting in map production.
• Goal of expanding project to include multiple geographical
locations
• Collaboration with Trent Teegerstrom (Ag Resource Economics)
– Tree Crop budgets for comparing conventional sprayer costs
with optical weed detecting sprayer technology.
0.00
0
10
Groundcover (%)
20
30
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