Cotton Response to Topical Fungicide Application Darrin M. Dodds 1 C. L. Main 2, L. T. Barber 3, J....
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Transcript of Cotton Response to Topical Fungicide Application Darrin M. Dodds 1 C. L. Main 2, L. T. Barber 3, J....
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
Foliar Diseases % Yield Reduction 0.10 -- 3.5 Trace 4
Bales Lost 625 -- 66,763 -- 32,500
Boll Rots % Yield Reduction 4 2 1 6 4
Bales Lost 25,031 30,337 19,075 20,241 32,500
Total Loss % Yield Reduction 4.1 2 4.5 6 8
Bales Lost 25,656 30,337 85,838 20,241 65,000
Dollars Lost $0.65 per pound $8.0 million
$9.5 million
$26.8 million
$6.3 million
$20.3 million
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. 2009Padgett 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. 2006Woodward 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. 2008Padgett et al. 2007Mailhot 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
Trade Name
Application Timing
Application Code
Application Rate
Application Rate
Kg ai ha-1 oz prod ac-1
Azoxystrobin Quadris™ 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
Pyraclostrobin Headline™ 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
• All agronomic and pest management practices performed according to local standards
• Data analyzed using Proc Mixed– Data pooled over
environments
• Plant height
• Total nodes
• % Hardlock
• Gin turnout
• Yield
• 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
0
10
20
30
40
50
60
70
80
90
100
110
Quadris 12 oz
Quadris 6 + 6 oz
Quadris 6 + 12 oz
Headline 12 oz
Headline 6 + 6 oz
Headline 6 + 12 oz
Untreated
LSD (0.05) = NSD
Fungicide
% o
f U
ntr
eat
ed C
he
ck
5 Locations in 2008 and 2009 p = 0.47
Growth and DevelopmentFungicide 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
Headline ™ 12 oz 18 21 39.2
6 + 6 oz 18 25 40.8
6 + 12 oz 18 22 40.1
Untreated -- 18 24 39.5
p 0.09 0.48 0.006
LSD (0.05) NS NS 0.01
Yield
0
10
20
30
40
50
60
70
80
90
100
110
Quadris 12 oz
Quadris 6 + 6 oz
Quadris 6 + 12 oz
Headline 12 oz
Headline 6 + 6 oz
Headline 6 + 12 oz
Untreated
LSD (0.05) = NSD
Fungicide
% o
f U
ntr
eat
ed C
he
ck
6 Locations in 2008 and 2009 p = 0.55
Fiber QualityFungicide Rate Mic Staple Strength Uniformity
------inches------ ------ g tex-1 ------- ------- %-------
Quadris™ 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
Headline ™ 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
Untreated -- 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
Return on Investment
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
Quadris 12 oz
Quadris 6 + 6 oz
Quadris 6 + 12 oz
Headline 12 oz
Headline 6 + 6 oz
Headline 6 + 12 oz
Untreated
Fungicide
$ R
etu
rned
6 Locations in 2008 and 2009
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 RateFungicide
CostEquivalent
PotashEquivalent
Lime
--------------------------------------- w/application ----------------------------------------
Quadris™ 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
Headline ™ 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