Transcript Cotton Response to Topical Fungicide Application

Cotton Response to Topical
Fungicide Application
Darrin M. Dodds1
C. L. Main2, L. T. Barber3, J. E. Woodward4, R. Boman4, J. Whitaker5, K.
Edmisten6, N. W. Buehring1, and T. Allen1.
Mississippi State University1, The University of Tennessee2, University of Arkansas3, Texas
AgriLife Extension Service4, University of Georgia5, North Carolina State University6
Introduction
• Extension Cotton Specialists Working
Group
• Research initiated in response to:
– Pyraclostrobin (Headline™) – 2007
– Azoxystrobin (Quadris™) – 2008
– Incidence of foliar disease over past
several growing seasons
Common Diseases
• Alternaria – lesions with brown or purple margins
– Older lesions have concentric rings with center falling out in some
• Cercospera – small red lesions that enlarge and have white to
brown center
– Avoid all stress – esp. potassium, destruction of residue
• Ascochyta – light brown lesions that coalesce on leaves
– Lesion have dark brown borders
• Stemphylium - small circular brown lesions with concentric rings
– Older lesions have a white center which can drop out.
• Helminthosporium leaf spot
Sciumbato 2009
Loss Due to Disease – 2008
Disease
State
AL
AR
GA
LA
MS
0.10
--
3.5
Trace
4
Bales Lost
625
--
66,763
--
32,500
% Yield Reduction
4
2
1
6
4
Bales Lost
25,031
30,337
19,075
20,241
32,500
% Yield Reduction
4.1
2
4.5
6
8
Bales Lost
25,656
30,337
85,838
20,241
65,000
$0.65 per pound
$8.0
million
$9.5
million
$26.8
million
$6.3
million
$20.3
million
Foliar Diseases % Yield Reduction
Boll Rots
Total Loss
Dollars Lost
Blasingame et al. 2009
Leaf Spot Disease and Yields
• Defoliation from leaf spot diseases reduced
by up to 85% following fungicide application
– Not always the case
• Preventative fungicide applications can be
effective in reducing foliar disease
– Minimal effect on yield
• Application of fungicide in the absence of disease
did not impact yield
Kemerait et al. 2009
Padgett et al. 2007
Woodward et al. 2009
Fungicide Effects on Hardlock
• Hardlock
– Thought to occur due to interaction of Fusarium spp. and flower
thrips
• Results of fungicide application to control hardlock
have been mixed
• Decreased incidence of hardlock and increased yield
following Quadris™ application
Lawrence et al. 2006
Woodward et al. 2009
Fungicide Effects on Hardlock
• Yield increases following fungicide application have
been observed
• Fungicide application when hardlock occurrence is
<30% is ineffective
• Limited utility of fungicides for control of hardlock
– No yield response due to foliar application
Jones et al. 2008
Padgett et al. 2007
Mailhot et al. 2008
Woodward et al. 2009
Justification
• Previous research has yielded mixed results
– Warrants further study to determine proper utility
• Previous research is limited
• Increased sales pressure
• Tremendous pressure to make every dollar
count
Materials and Methods
• Small plot research
– RCBD – 4 replications
• Participating states:
– Arkansas
– Georgia
– Mississippi
– North Carolina
– Tennessee
– Texas
Treatments
Common
Name
Azoxystrobin
Pyraclostrobin
Trade
Name
Quadris™
Headline™
Application
Timing
Application
Code
Application
Rate
Application
Rate
Kg ai ha-1
oz prod ac-1
1st Bloom
A
0.11
12
1st Bloom
A
0.11
6
14-21 DAA
B
0.11
6
1st Bloom
A
0.11
6
14-21 DAA
B
0.22
12
1st Bloom
A
0.11
12
1st Bloom
A
0.11
6
14-21 DAA
B
0.11
6
1st Bloom
A
0.11
6
14-21 DAA
B
0.22
12
Materials and Methods
• Locally adapted
varieties utilized
• Plant height
• Total nodes
• All agronomic and pest
management practices
performed according to
local standards
• % Hardlock
• Data analyzed using
Proc Mixed
• Yield
– Data pooled over
environments
• Gin turnout
• Fiber quality
Figure 1. Untreated cotton foliage
Figure 2. Quadris 6 oz early bloom + 6 oz 21 d.
Figure 3. Headline 6 oz early bloom + 6 oz 21 d.
End of Season Plant Height
110
LSD (0.05) = NSD
100
% of Untreated Check
90
80
70
60
50
40
30
20
10
0
Quadris
12 oz
5 Locations in 2008 and 2009
Quadris
6 + 6 oz
Quadris
6 + 12 oz
Headline
12 oz
Fungicide
Headline
6 + 6 oz
Headline
6 + 12 oz
Untreated
p = 0.47
Growth and Development
Fungicide
Rate
Total Nodes
Hardlock
Turnout
-------- # -------- ------------------- % ------------------Quadris™
12 oz
17
25
40.0
6 + 6 oz
18
22
40.5
6 + 12 oz
17
21
40.3
12 oz
18
21
39.2
6 + 6 oz
18
25
40.8
6 + 12 oz
18
22
40.1
--
18
24
39.5
p
0.09
0.48
0.006
LSD (0.05)
NS
NS
0.01
Headline ™
Untreated
Yield
110
LSD (0.05) = NSD
100
% of Untreated Check
90
80
70
60
50
40
30
20
10
0
Quadris
12 oz
6 Locations in 2008 and 2009
Quadris
6 + 6 oz
Quadris
6 + 12 oz
Headline
12 oz
Fungicide
Headline
6 + 6 oz
Headline
6 + 12 oz
Untreated
p = 0.55
Fiber Quality
Fungicide
Rate
Quadris™
Mic
Staple
Strength
Uniformity
------inches------
------ g tex-1 -------
------- %-------
12 oz
4.0
1.16
30.9
82.4
6 + 6 oz
4.0
1.17
29.7
82.1
6 + 12 oz
4.1
1.17
30.5
83.0
12 oz
3.9
1.15
29.6
82.1
6 + 6 oz
4.2
1.14
30.2
82.3
6 + 12 oz
4.1
1.14
29.9
82.3
--
4.1
1.15
30.0
82.5
p
0.58
0.04
0.001
0.1773
LSD (0.05)
NS
0.02
0.6
NS
Headline ™
Untreated
Return on Investment
0
-5
-10
$ Returned
-15
-20
-25
-30
-35
-40
-45
-50
Quadris
12 oz
6 Locations in 2008 and 2009
Quadris
6 + 6 oz
Quadris
6 + 12 oz
Headline
12 oz
Fungicide
Headline
6 + 6 oz
Headline
6 + 12 oz
Untreated
Conclusions
• Fungicides can control foliar disease
– Application timing is critical
• No differences in plant growth and development
• No yield benefits
• No fiber quality benefits
• More research needed
Discussion
• Important to determine cause of foliar disease and/or
boll rot
• Disease pressure usually exacerbated by other
factors
• Fertility
– Foliar disease often associated with potassium
– Boll rot can be enhanced by excess nitrogen
• Are low nutrient levels in the soil the culprit?
– What about adequate nutrients in the soil and shortages in
leaf tissue?
Discussion
• Peak potassium uptake during 3rd – 4th
week of bloom
• Early maturing, fast fruiting varieties
• Fungicide application is not cheap
Equivalent Costs
Fungicide
Rate
Fungicide
Cost
Equivalent
Potash
Equivalent
Lime
--------------------------------------- w/application ----------------------------------------
Quadris™
Headline ™
12 oz
$36.53
111 lbs
1 ton
6 + 6 oz
$42.03
132 lbs
1.2 tons
6 + 12 oz
$57.55
194 lbs
1.6 tons
12 oz
$38.50
121 lbs
1.1 tons
6 + 6 oz
$44.00
142 lbs
1.3 tons
6 + 12 oz
$60.50
205 lbs
1.7 tons
Take Home Message
• Proper utility of foliar fungicides yet to
be determined
– Avoid use where not necessary due to
resistance concerns
• Reduce plant stress
• Maximize profit every dollar spent
Questions