2014 Extension Agent Training
Loren Fisher & Matthew Vann
Department of Crop Science
GAP Update
• General GAP Program will remain unchanged.
– Production updates and labor training
• DOL will ATTEMPT to be at every meeting.
– Early scheduling should ensure their presence.
– DOL is offering a training session December 8th at 12:30 in
the Martin Building at the fairgrounds.
• GAP material requests have been opened by GAP
Connections.
– GAP Connections will mail the requested material to your
office.
– If hosting a joint meeting with another county(ies), please
group all requests together.
– http://www.gapconnections.com/Pages/TrainingEvents.aspx
GAP Update
• We will offer GAP Connections signup again
this year at meetings.
– No registration on-site.
– Scanning of GAP Connections Membership cards
will occur.
• Scanners will be provided through NCSU at every
meeting.
• Meals are covered by NCSU
Greenhouse Issues
Boron Management
• Collect source water sample prior to seeding
– <0.5 ppm B is considered low
• If B is low, select fertilizer with at least 0.01% B.
• Collect a diagnostic water sample from the float bed after fertilizer
application to ensure that B levels are sufficient (1-2 ppm)
• If B is still in short supply consider adding a B fertilizer material
– Borax @ 0.2 oz/100 gallons of water will add 1.5 ppm B to the float bed
• Keep air temperature as warm as possible (maximum 86°F)
– Cool temperatures and cold shock promote B deficiency
– B uptake ↓ by 50% when temperature is reduced from 79 to 57°F
• REMEMBER- Boron is toxic to greenhouse plants when float bed
concentration exceeds 2 ppm
– When determining B concentration it is critical that source water B and
fertilizer B are totaled
Source: NCSU Soil Facts AGW-439-48, http://content.ces.ncsu.edu/20218.pdf
Nitrogen Application
Current Practices: Nitrogen Application
• Growers are applying fertilizer in two applications.
• The first fertilizer application is applied as either a band or a
broadcast before transplanting or just after transplanting. 50% of
N and 100% of P and K.
• The second application is made just before the lay-by growth
stage of the plant (three to five weeks after transplanting or 15-20
inches tall), banded. Remainder of N.
• Nutrients are not normally added after lay-by as field implements
cannot pass over plants without damaging.
Potential Complications with Split
Application
• Amount of nitrogen applied is based on
extension recommendations and field
experience.
• Estimation based on soil type and expected
rainfall.
• End up with too much N in a dry year and not
enough in a wet year.
Justification of Research
• With the use of liquid nitrogen (Urea
ammonium nitrate, UAN) becoming popular,
later applications are now possible with high
clearance equipment.
• According to NC Extension 50% of tobacco
acreage receives at least some of its nitrogen
from UAN.
Justification of Research
• Benefits of UAN include
– Ease of handling
– Less fill-ups
– More flexibility in application timing
– Cost savings
Justification of Research
• Applying nitrogen in more than two
applications would allow growers to base
nitrogen rates on current growing conditions in
ADDITION to previous field experience.
• Rainfall amounts, soil texture, estimated water
percolation, and crop condition would
determine need for additional nitrogen.
– Drought conditions vs. excess rainfall.
Environments
•
Border Belt Tobacco Research (BBTRS) in Whiteville, NC. (2012 & 2013)
•
Oxford Tobacco Research Station (OTRS) in Oxford, NC (2012 & 2013)
•
Upper Coastal Plain Research Station (UCPRS) Rocky Mount, NC (2013)
•
Representative of Coastal Plain & Piedmont (major tobacco producing regions
in NC)
Methods & Materials
•
Nitrogen applications were made two to four times per season.
•
Possible application timings evaluated were at planting, at 6 in. plant height, at 15-20 in.
plant height (layby), at 24-30 in. plant height and at 48 in. plant height (topping).
•
Timings corresponded with approximately 0, 2, 4, 6, and 8 weeks after transplanting.
•
Base rates of nitrogen were based on recommended rates for each location.
•
Within each environment, rates of nitrogen applied were 75% of the total nitrogen
recommended rate, 100% of the total nitrogen recommended rate, or 125% of the total
nitrogen recommended rate.
Methods & Materials
• Nitrogen was soil applied using a simulated soil
directed application technique and was then
incorporated with a Danish tine rolling cultivator.
• Applications after layby were done to simulate drop
nozzles used by high clearance sprayers to apply
nitrogen to the soil surface.
Nitrogen application timing and amount applied relative to
recommended nitrogen rates at each environment.
Treatment Number
------------------------------------------Nitrogen Application Timing---------------------------------------At Transplanting
2 Weeks after transplanting1
At layby2
2 Weeks after layby3
At Topping
1 (Control)
50%
-
50%
-
-
2
50%
25%
-
-
-
3
25%
25%
25%
25%
-
4
25%
25%
25%
-
-
5
25%
-
25%
25%
25%
6
25%
-
25%
25%
-
7
25%
25%
-
-
50%
8
25%
-
25%
-
25%
9
50%
-
50%
-
25%
10
50%
-
25%
-
25%
P values for yield, quality, value, total alkaloids, reducing sugars, leaf nitrogen
content at layby, leaf nitrogen content at topping, and SPAD measurements.
Variable
Pr>F Env* Rate/Timing
Pr>F Rate/Timing
Yield
0.7037
0.3448
Quality
0.9803
0.5747
Value
Total Alkaloids
0.8286
0.0618
0.3988
<0.0001*
Total Reducing Sugars BBTRS-12
---
0.1201
Total Reducing Sugars OTRS-12
Total Reducing Sugars BBTRS-13
-----
0.0026*
0.3415
Total Reducing Sugars OTRS-13
---
0.574
Total Reducing Sugars UCPRS-13
Leaf nitrogen content at layby
--0.1454
0.1585
0.0038*
Leaf nitrogen content at topping BBTRS-12
---
0.0917
Leaf nitrogen content at topping OTRS-12
---
0.0250*
Leaf nitrogen content at topping BBTRS-13
---
0.0039*
Leaf nitrogen content at topping OTRS-13
---
0.8992
Leaf nitrogen content at topping UCPRS-13
---
0.0090*
SPAD BBTRS-12
---
0.0558
SPAD OTRS-12
SPAD BBTRS-13
-----
0.0461*
0.0012*
SPAD OTRS-13
---
0.8946
SPAD UCPRS-13
---
0.0187*
Yield, quality, and value response to nitrogen rate and
timing combined over environments.
Treatment
Number
---------------------------Nitrogen Application Timing-------------------------
Quality
Index1
2 WAT
At layby
1 (Control)
50%
-
50%
-
-
2,567 a
80 a
4,248 a
2
50%
25%
-
-
-
2,591 a
82 a
4,376 a
3
25%
25%
25%
25%
-
2,463 a
82 a
4,245 a
4
25%
25%
25%
-
-
2,481 a
83 a
4,345 a
5
25%
-
25%
25%
25%
2,771 a
80 a
4,633 a
6
25%
-
25%
25%
-
2,525 a
82 a
4,292 a
7
25%
25%
-
-
50%
2,474 a
78 a
3,977 a
8
25%
-
25%
-
25%
2,488 a
79 a
3,979 a
9
50%
-
50%
-
25%
2,542 a
78 a
4,051 a
10
50%
-
25%
-
25%
2,632 a
84 a
4,603 a
et al. Revised North Carolina grade index for flue-cured tobacco. 1988
---Lbs/ac---
Value
At Transplanting
1Bowman
2 WALayby At Topping
Yield
--$/ac--
Total alkaloids and leaf nitrogen content at layby responses to
nitrogen rate and timing combined over environments.
Treatment Number
---------------------------Nitrogen Application Timing-------------------------
Nitrogen
Total alkaloids content at
layby
At Transplanting
2 WAT
At layby
2 WALayby
At Topping
---------------%---------------
1 (Control)
50%
-
50%
-
-
2.65 cde
4.34 ab
2
50%
25%
-
-
-
2.49 ef
4.61 a
3
25%
25%
25%
25%
-
2.54 def
4.15 bc
4
25%
25%
25%
-
-
2.41 f
4.17 bc
5
25%
-
25%
25%
25%
2.76 abc
4.10 bc
6
25%
-
25%
25%
-
2.43 f
4.00 c
7
25%
25%
-
-
50%
2.85 ab
4.23 bc
8
25%
-
25%
-
25%
2.56 cdef
4.04 bc
9
50%
-
50%
-
25%
2.95 a
4.29 bc
10
50%
-
25%
-
25%
2.72 bcd
4.34 ab
Discussion
• The highest total alkaloid percentages were from treatments that had
100% or 125% of the recommended rate of nitrogen.
• The four highest total alkaloid percentages also had a late season
nitrogen application at the “at topping” timing interval.
• Differences in N content at layby likely because not all of the
treatments had all nitrogen applied at the time of sampling.
• There were treatments that had 50% of the nitrogen applied after the
layby stage, these treatments had less leaf nitrogen content than
treatments that had already had 100% of the recommended rate
applied when the samples were taken.
Discussion
• Higher reducing sugar levels observed at 75%
of the total recommended nitrogen rate.
Leaf nitrogen content at topping in response
to nitrogen rate and timing by environment.
Treatment
------------Nitrogen Application Timing----------
BBTRS-12
OTRS-12
BBTRS-13
OTRS-13
UCPRS-13
At
Transplanting
2
WAT
At layby
2
WALayby
At
Topping
1
(Control)
50%
-
50%
-
-
2.11a
3.88 abc
1.54 cd
2.93 a
2.48 a
2
50%
25%
-
-
-
1.87 a
4.19 ab
1.43 d
2.84 a
1.79 c
3
25%
25%
25%
25%
-
1.91 a
4.30 a
1.73 cd
3.04 a
2.00 bc
4
25%
25%
25%
-
-
1.85 a
3.61 c
1.52 cd
2.87 a
2.07 bc
5
25%
-
25%
25%
25%
2.15 a
3.50 c
2.56 a
2.85 a
2.03 bc
6
25%
-
25%
25%
-
1.99 a
3.73 bc
1.97 bc
2.91 a
2.05 bc
7
25%
25%
-
-
50%
2.57 a
3.79 bc
2.26 ab
2.76 a
1.83 c
8
25%
-
25%
-
25%
1.84 a
4.13 ab
1.72 cd
2.88 a
2.33 ab
9
50%
-
50%
-
25%
2.18 a
4.20 ab
1.75 cd
3.16 a
2.46 a
10
50%
-
25%
-
25%
1.97 a
3.83 abc
1.76 cd
2.86 a
2.03 bc
---------------% Nitrogen at Topping---------------
Discussion
• The highest nitrogen levels “at topping” were
generally in plots where later nitrogen
applications were made.
Conclusion
• Rate of nitrogen and timing had very little affect on leaf quality.
• Leaf chemistry was affected by nitrogen rate and timing.
• Current nitrogen rate recommendations appear to be adequate for
optimum yield and quality.
• Weather played a major role in this study.
• Had less rainfall occurred some of the late season applications may
have resulted in a decreased leaf quality.
• Further research is still needed to determine if a late season
application would not harm quality due to delayed ripening of the
leaf.
Rainfall Table by month for individual
environments
Month
BBTRS-121
OTRS-122
BBTRS-133
OTRS-134
UCPRS-135
------------------------------------------------------------Inches----------------------------------------------------------------April
2.32
3.90
2.28
4.57
2.68
May
8.98
6.14
22.64
4.57
2.87
June
2.28
2.24
25.79
10.35
9.96
July
8.11
11.06
12.32
9.49
4.92
August
14.37
6.50
6.65
4.21
4.53
September
4.17
5.43
4.72
1.93
4.84
October
4.49
2.48
1.06
2.32
3.27
Total
44.72
37.76
75.47
37.44
33.07
Average
31.50
27.56
31.50
27.56
27.56
Percent above
average
41%
37%
140%
37%
20%
Objective
• Evaluate Soil Applied and Stalk Run-down methods
for late season N application.
Nitrogen application timings, rates, and
method.
Treatment Number
Method of
Application
-----------------Nitrogen Application Timing---------------
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks after
transplanting
At Topping
1 (Control)
50%
-
50%
-
-
SA
2 (Control)
50%
25%
-
-
-
SA
3
25%
-
25%
25%
25%
SA/SR
4
25%
-
25%
25%
25%
SA
5
-
25%
25%
-
50%
SA/SR
6
-
25%
25%
-
50%
SA
7
50%
-
50%
-
25%
SA/SR
8
50%
-
50%
-
25%
SA
Nitrogen application timings, rates, and
method.
Treatment Number
Method of
Application
-----------------Nitrogen Application Timing---------------
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks after
transplanting
At Topping
1 (Control)
50%
-
50%
-
-
SA
2 (Control)
50%
25%
-
-
-
SA
3
25%
-
25%
25%
25%
SA/SR
4
25%
-
25%
25%
25%
SA
5
-
25%
25%
-
50%
SA/SR
6
-
25%
25%
-
50%
SA
7
50%
-
50%
-
25%
SA/SR
8
50%
-
50%
-
25%
SA
Nitrogen application timings, rates, and
method.
Treatment Number
Method of
Application
-----------------Nitrogen Application Timing---------------
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks after
transplanting
At Topping
1 (Control)
50%
-
50%
-
-
SA
2 (Control)
50%
25%
-
-
-
SA
3
25%
-
25%
25%
25%
SA/SR
4
25%
-
25%
25%
25%
SA
5
-
25%
25%
-
50%
SA/SR
6
-
25%
25%
-
50%
SA
7
50%
-
50%
-
25%
SA/SR
8
50%
-
50%
-
25%
SA
Nitrogen application timings, rates, and
method.
Treatment Number
Method of
Application
-----------------Nitrogen Application Timing---------------
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks after
transplanting
At Topping
1 (Control)
50%
-
50%
-
-
SA
2 (Control)
50%
25%
-
-
-
SA
3
25%
-
25%
25%
25%
SA/SR
4
25%
-
25%
25%
25%
SA
5
-
25%
25%
-
50%
SA/SR
6
-
25%
25%
-
50%
SA
7
50%
-
50%
-
25%
SA/SR
8
50%
-
50%
-
25%
SA
P values for yield, quality, value, total alkaloids, reducing sugars,
leaf nitrogen content at layby, leaf nitrogen content at topping, and
SPAD measurements.
Variable
Pr>F
Env*Ntime*Nmeth
Pr>F
Env*Ntime
Pr>F
Env*Nmeth
Pr>F
Ntime*Nmeth
Pr>F Ntime
Pr>F Nmeth
Yield
0.1417
0.3806
0.3801
0.8075
0.2457
0.0456*
Quality
0.0658
0.0822
0.2719
0.0008*
0.3654
0.9720
Value
0.0344*
0.2361
0.7458
0.0362
0.6047
0.1931
Total Alkaloids
0.9540
0.3982
0.9408
0.9242
0.2022
0.0973
Total Reducing
0.6334
0.5110
0.4165
0.7215
0.0439*
0.1496
Leaf nitrogen content
at layby
0.6924
0.0058*
0.5272
0.1005
0.2924
0.5611
Leaf nitrogen content
at topping
0.3820
0.8992
0.0041*
0.4308
0.2077
<.0001*
SPAD
0.8877
0.7962
0.0160*
0.7421
0.2947
0.0629
Yield response to application method
combined across all environments.
Application Method
Yield
-----lbs/ac-----
Soil Applied
2,592 a
Stalk Run-down
2,480 b
Grade index response to nitrogen application rate, timing,
and method combined across all environments.
-----------------Nitrogen Application Timing---------------
Method of
Application
Quality Index
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks
after
transplant
At Topping
25%
-
25%
25%
25%
SA/SR
81 ab
25%
-
25%
25%
25%
SA
76 b
-
25%
25%
-
50%
SA/SR
74 b
-
25%
25%
-
50%
SA
84 a
50%
-
50%
-
25%
SA/SR
83 a
50%
-
50%
-
25%
SA
79 ab
Value response to nitrogen application rate, timing, and
method at individual environments.
-----------------Nitrogen Application Timing---------------
Method of
Application
BBTRS-12
OTRS-12
OTRS-13
UCPRS-13
At Transplanting
2 Weeks after
transplanting
At
layby
6 Weeks
after
transplant
At Topping
25%
-
25%
25%
25%
SA/SR1
5,373 a
4,996 a
4,043 a
2,381 a
25%
-
25%
25%
25%
SA2
4,675 a
5,246 a
4,345 a
2,245 ab
-
25%
25%
-
50%
SA/SR1
4,130 a
4,835 a
3,614 a
2,050 abc
-
25%
25%
-
50%
SA2
5,254 a
5,145 a
5,709 a
1,806 bc
50%
-
50%
-
25%
SA/SR1
5,194 a
5,155 a
5,417 a
1,525 c
50%
-
50%
-
25%
SA2
5,632 a
4,981 a
4,403 a
1,836 bc
--------------------$/ac--------------------
Discussion
• For value, the only environment with a significant
treatment effect was the Upper Coastal Plains
Research Station in 2013.
• The three treatments that received the highest
value per acre were treatments that had only
100% of the recommended rate of nitrogen
applied.
• The increase in yield from the soil applied
nitrogen method when evaluating yield combined
with the differences in quality index likely led to
differences in crop value.
Reducing sugar percentage in response to application timing
combined across all environments and method of application.
-----------------Nitrogen Application Timing---------------
Reducing Sugars
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks
after
transplant
At Topping
-----%-----
25%
-
25%
25%
25%
15.22 a
-
25%
25%
-
50%
13.66 b
50%
-
50%
-
25%
14.26 ab
Discussion
• Treatments with a portion of their nitrogen
applied at transplant had less nitrogen applied
late in the season allowing for starch to
accumulate earlier.
Leaf nitrogen content at layby in response to nitrogen
application timing by individual environment and combined
over application method.
-----------------Nitrogen Application Timing---------------
Leaf Nitrogen Content at layby
BBTRS-12 OTRS-12
OTRS-13
UCPRS-13
At Transplanting
2 Weeks after
transplanting
At layby
6 Weeks after
transplanting
At Topping
25%
-
25%
25%
25%
3.75 a
4.04 a
3.72 b
4.11 a
-
25%
25%
-
50%
3.72 a
4.78 a
4.34 a
3.59 b
50%
-
50%
-
25%
3.61 a
4.04 a
4.63 a
4.15 a
------------------------------%---------------------------------
Leaf nitrogen content at topping in response to nitrogen
application method combined over timings of application.
Application Method
Leaf Nitrogen Content at topping
BBTRS-12
OTRS-12
OTRS-13
UCPRS-13
------------------------------%---------------------------------
Stalk rundown
2.68 a
4.90 a
3.63 a
2.01 a
Soil applied
2.50 a
4.00 b
3.14 b
1.77 a
Conclusions
• Can use later season applications of nitrogen with the use of high clearance
sprayers and UAN with more flexibility than once thought.
• Growers have been doing this to make leaching adjustments, but with
lower rates than evaluated in this study.
• Soil applied nitrogen appears to be more efficient from a plant use
standpoint than stalk rundown method of application.
• Because of excessive rainfall in both years we were not able to determine
how late is too late and what amount of N is too great. The theory was
verified, but not the practice.
• Would prefer to deal with excessive N applied early than late, but delaying
a portion of the N applied until 6-8 weeks after transplanting (total of 3
applications) would provide for better N management flexibility with
minimal risk.
Rainfall Table by month for individual
environments
Month
BBTRS-121
OTRS-122
BBTRS-133
OTRS-134
UCPRS-135
------------------------------------------------------------Inches----------------------------------------------------------------April
2.32
3.90
2.28
4.57
2.68
May
8.98
6.14
22.64
4.57
2.87
June
2.28
2.24
25.79
10.35
9.96
July
8.11
11.06
12.32
9.49
4.92
August
14.37
6.50
6.65
4.21
4.53
September
4.17
5.43
4.72
1.93
4.84
October
4.49
2.48
1.06
2.32
3.27
Total
44.72
37.76
75.47
37.44
33.07
Average
31.50
27.56
31.50
27.56
27.56
Percent above
average
41%
37%
140%
37%
20%
2014 Boron Deficiency
• Symptoms:
– Deformed Bud
– Misshapen Leaves
– Twisted Bud/Leaves
• Likely Causes:
–
–
–
–
Cool Temperatures (GH)
Low Soil B
Excessive Rainfall
Rapid Plant Growth
Photos Courtesy of David Dycus (retired NCDA Agronomist)
Boron Deficiency Symptoms
Photos courtesy of
Dr. David Hardy, NCDA
Boron Deficiency Symptoms
Addressing Boron Issues in the Field
• Consider using a base fertilizer material that will supply 0.25-0.50
pounds of B per acre.
– Consider tank mixing liquid B with liquid N where dry materials are not utilized
• Implement a tissue sampling program, with the knowledge that it
provides limited information.
– Begin sampling 2-3 weeks following transplanting
– Collect the Most Recently Mature Leaf (4th or 5th leaf below the bud)
• 8-12 leaves per field should be a large enough sample, if growth is uniform
– Sample every two weeks until first harvest
• Only apply foliar B if tissue samples are deficient.
– 0.5 lbs B/acre in a single application should correct deficiency
– DO NOT apply unless nutrient deficiency is confirmed
– DO NOT over apply, B can be toxic at 1.0 lb/acre
• 0.25 lbs B/acre + 0.25 lbs B/acre, both applied foliar
2014 Calcium Deficiency
• Ca is not rapidly
translocated within the
plant nor is it remobilized
• Bud/tip leaves are most
likely show deficiency
– Downward cupping/hooded look
• Typically occurs at flowering
– Result of rapid plant growth
• Often disappears once
topping occurs
– Removal of affected tissue
– Root growth stimulation
Lower Photo Courtesy of Mitch Smith-Pitt County Extension Agent
Addressing Calcium Issues in the Field
• Collect routine soil samples in each field that tobacco
will be produced in.
– This will determine the amount of soil available Ca
• Most tobacco fields will have sufficient Ca reserves.
• To prevent or reduce the risk of Ca deficiency top
plants as early as possible.
– Topping will stimulate root growth, which increases Ca
uptake
• Ca deficiency is transient and will correct itself
– Foliar Ca applications are not recommended
– Little to no foliar Ca uptake, must be absorbed in the roots
Weed Control
Overview: Treatments & Methodology
for Year One (Tobacco)
• RCBD with Factorial treatment arrangement
• Main Effects: Two Tillage Methods
– Deep
– Shallow
• Sub-Plot Effect: Two Herbicide Programs
– Clomazone (0.75 lbs. ai/acre) applied PPI to entire study
– Clomazone (0.75 lbs. ai/acre) & Sulfentrazone (0.19 lbs. ai/acre)
• Sulfentrazone applied PRE-TRANSPLANT per protocol
• Sub-Plot Effect: Hand weeded vs. Non-handweeded
– Hand weeding occurred late season, prior to weed seed development
• Weed counts taken prior to layby. Each before cultivation took
place.
– 4 ft. x 4 ft. sampling square
• Yield, quality, and value were assessed at the end of the season.
Year One Results: Tobacco
First
Rating
Treatment
Shallow Tillage & Sulfentrazone +
Clomazone
Second
Rating
Third
Rating
------------------------num./acre------------------------
Yield
Quality
-lbs./acre-
2,949 b
335 b
ns
ns
ns
115,933 a
54,112 a
ns
ns
ns
0b
0b
ns
ns
ns
Deep Tillage & Clomazone
28,577 b
15,428 b
ns
ns
ns
Sulfentrazone + Clomazone
1,474 b
167 b
9,924 b
2,372 a
80 a
72,259 a
34,770 a
109,920
a
987 b
69 b
Shallow Tillage
59,441 a
27,224 a
74,075 a
1,506 b
71 a
Deep Tillage
14,292 a
7,714 a
45,769 a
1,854 a
78 a
Hand Weed
--
--
--
--
--
No Hand Weed
--
--
--
--
--
Shallow Tillage & Clomazone
Deep Tillage & Sulfentrazone +
Clomazone
Clomazone
Year One: Tobacco Rotation
Shallow Tillage + Sulfentrazone & Clomazone + No
Hand Weeding
Shallow Tillage + Sulfentrazone & Clomazone + No
Hand Weeding
Shallow Tillage + Clomazone + No Hand Weeding
Shallow Tillage + Clomazone + No Hand Weeding
Year One: Tobacco Rotation
Deep Tillage + Sulfentrazone & Clomazone +
No Hand Weeding
Deep Tillage + Sulfentrazone & Clomazone +
No Hand Weeding
Deep Tillage + Clomazone + No Hand Weeding
Deep Tillage + Clomazone + No Hand Weeding
Disc + Command + No Weeding
Overview: Treatments & Methodology
for Year Two (Cotton)
• RCBD with Factorial treatment arrangement
• No tillage treatments implemented
• No PRE herbicide treatments implemented
– POST herbicide application only, applied to all plots
• Glyphosate @ 0.95 lbs. ai/acre & 1.50 lbs. ai/acre
• Glufosinate @ 0.73 lbs. ai/acre
• Sub-Plot Effects: Hand weeded vs. Non-handweeded
– Hand weeding occurred late season, prior to weed seed
development
• Weed counts taken prior to POST herbicide application
– 4 ft x 4 ft sampling square
Weed Control Results: Year Two
First Rating
Second Rating
----num./acre----
----num./acre----
Sulfentrazone + Clomazone & Hand Weed
ns
49,684 b
Sulfentrazone + Clomazone & No Hand Weed
ns
66,700 b
Clomazone & Hand Weed
ns
66,359 b
Clomazone & No Hand Weed
ns
249,788 a
Sulfentrazone + Clomazone
205,378 b
58,192 b
Clomazone
464,015 a
158,074 a
Shallow Tillage
352,052 a
119,108 a
Deep Tillage
317,340 a
97,158 a
Hand Weed
180,365 b
58,022 b
No Hand Weed
473,714 a
158,244 a
Treatment
Year Two: Cotton Rotation
Cotton stand and weed control
without sulfentrazone
Cotton stand and weed control
with sulfentrazone
Year Two: Cotton Rotation
Cotton stand and weed control,
without hand weeding
Cotton stand and weed control,
with hand weeding
Two Year Economic Impact
Year One: Tobacco
Hand Weed
Time
Production
Cost
Year Two: Cotton
Production
Return
----------$/acre----------
Hand Weed
Time
---min/acre---
Production
Cost
Total
Production
Return
----------$/acre----------
Return
Treatment
---min/acre---
----$/acre----
Tillage*HW
ns
ns
ns
ns
ns
ns
ns
Shallow Tillage
26 a
3,158 b
156 b
30 a
749 a
163 a
322 a
Deep Tillage
41 a
3,193 a
1,152 a
25 a
740 a
138 a
1,292 b
Hand Weed
69 a
3,180 a
716 a
56 a
755 a
169 a
886 a
No Hand Weed
0b
3,171 b
596 a
0b
734 a
133 a
727 a
Preliminary Conclusions:
Weed Suppression and Crop Yield
• For Tobacco Production:
– Sulfentrazone had the largest impact to reduced Palmer
pressure.
• 91-100% control depending on treatment comparison and rating date
– Deep tillage + sufentrazone treatments were weed free until layby
– Tillage did not effect weed suppression.
• For Cotton Production:
– Sulfentrazone application to the previous tobacco crop.
• 56 & 61% increase in weed suppression, compared to plots not
treated with sulfentrazone
– Tillage from previous crop had no effect on weed suppression.
– Hand weeding in previous crop.
• Reduced weed pressure at both ratings by ≈60%
Preliminary Conclusions:
Economics of Tillage and Hand Weeding
• For Tobacco Production:
– Deep tillage increased cost of production by $35/acre
• Increased economic return by ≈$1,000/acre
– Due to increased crop yield
– Hand weeding increased production cost by $9/acre
• No impact to economic return
• For Cotton Production:
– Tillage from previous crop did not impact time of hand weeding,
production cost, or economic return.
– Hand weeding cotton did not increase production cost or economic
return.
• Two Year Return:
– Deep tillage increased economic return by ≈$1,000/acre.
• Due to yield increase from deep tillage and herbicide program in tobacco
Grower Recommendations
• Utilize deep tillage, where feasible.
– Must comply with federal and state soil conservation plans
• Utilize sulfentrazone and clomazone.
– Can expect excellent amaranth, morningglory (Ipomoea),
nutsedge (Cyperus), and grass suppression
• Hand weed as needed.
– Must remove weeds prior to seed set
• Reduce weed seed bank
– Recommended that producers transport weeds from the field
for disposal
• Regrowth prevention
Other Issues.....
Questions??