DISEASE AND FUNGICIDE MANAGEMENT FOR CORN & WHEAT Heather M. Kelly Field Crops Plant Pathology West Tennessee Research and Education Center University of Tennessee
Disease Pyramid 1. Plant susceptible variety 2. Pathogen influenced by field history, location, etc. 3. Environment promotes disease development For yield loss to be an issue 4. Time all 3 factors have to occur at a critical time/growth stage
Image from southernstates.com F6-F9 Scout for leaf diseases - infections begin on lower leaves F 10.5.1 Spray for Scab fungus infects through the blooms
Wheat Diseases ars.usda.gov Powdery Mildew Leaf/Septoria Blotch Glume/Stagonospora Blotch Stripe Rust Leaf Rust May require fungicide application before heading Use Strobilurin and/or Triazole fungicides Fusarium Head Blight (Scab) } Fungicide application at bloom Use ONLY Triazole fungicides
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Wheat Diseases Powdery Mildew Leaf/Septoria Blotch Glume/Stagonospora Blotch Stripe Rust Leaf Rust Fusarium Head Blight (Scab)
Wheat Diseases Leaf/Septoria Blotch Glume/Stagonospora Blotch
Wheat Diseases Stripe Rust ars.usda.gov
Wheat Diseases Leaf Rust
Wheat Diseases Fusarium Head Blight (FHB, Head Scab) www.wheatscab.psu.edu
http://www.wheatscab.psu.edu/ State Model Variety Susceptibility Date
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2013 Wheat Fungicide Trials Average across fungicides at 2 locations Yield (bu/a) F6-F8 c Untreated c F5-F6 F5-F6 + F10.5.1 F8-F10 bc abc ab F10.5.1 a 44.0 46.0 48.0 50.0 52.0 54.0 *Same letters indicate no significant difference
F5-F6 F8-F10 F10.5.1 2013 Trial Leaf Rust % Caramba 13.5 fl oz/a Caramba 10 fl oz/a Prosaro 6.5 fl oz/a Folicur 4 fl oz/a Caramba 13.5 fl oz/a Twinline 7 fl oz/a Quilt Xcel 14 fl oz/a Tilt 4 fl oz/a Folicur 4 fl oz/a Prosaro 6.5 fl oz/a Headline 6 fl oz/a Stratego YLD 4 fl oz/a Twinline 7 fl oz/a Tilt 4 fl oz/a Folicur 4 fl oz/a Stratego YLD 4 fl oz/a Untreated Headline 6 fl oz/a e e e d c c c c c c c Yield not significantly effected (ranged from 46.6 to 53.2 bu/a) *Same letters indicate no significant difference b ab ab ab a a a 0 5 10 15 20
Corn Growth Stages Image from Illinois Extension publication
Corn Diseases Grey Leaf Spot Most common Common Rust = cooler temp Cooler temperatures (61-77 F) Brown, elongated pustules On both sides of leaf Southern Rust Warmer temperatures (77-82 F) Orange, round pustules On upper leaf surface Northern Leaf Blight Usually not a yield robber in TN
Corn Diseases Grey Leaf Spot Most common Common Rust = cooler temp Cooler temperatures (61-77 F) Brown, elongated pustules On both sides of leaf Southern Rust Warmer temperatures (77-82 F) Orange, round pustules On upper leaf surface Northern Leaf Blight Usually not a yield robber in TN Upper side of leaf Lower side of leaf
Corn Diseases Grey Leaf Spot Most common Common Rust = cooler temp Cooler temperatures (61-77 F) Brown, elongated pustules On both sides of leaf Southern Rust Warmer temperatures (77-82 F) Orange, round pustules On upper leaf surface Northern Leaf Blight Usually not a yield robber in TN
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2014 Regional Corn Fungicide Summary Data from 15 states and Ontario, Canada Timing of application # of fungicides tested # of observations Mean yield response compared to nontreated control (bu/a) * Early (V3-V8) 14 143 2.3 Standard (VT-R2) Double (V5 + VT/R1) 16 207 7.6 8 112 4.9 * Mean calculated over all fungicides compared in individual state trials
Mean yield response compared to non-treated control in bu/a over time 2010 n=160 2011 n=57 2012 n=343 2013 n=425 2014 n=462 Avg n=1447 Early (V5-V8) 3.4 2.1-1.1 0.1 2.3 1.0 Standard (VT-R2) 4.5 0.4 4.9 4.5 7.6 5.4 Double (V5 + R1) 7.4 4.5 3.0 3.7 4.9 4.4
Mean yield response compared to non-treated control in bu/a over time Tennessee Data 2013 2014 2015 Avg Early (V5-V8) n=34-3.3 3.0 6.4 2.6 Standard (VT-R1) n=32 3.2 7.1 9.6 7.9 Double (V5-V7 + VT-R1) n=15 7.3 3.5 13.9 4.6
Break-even scenarios for corn Corn price ($/bu) Application cost ($/A) $12 $16 $20 $24 $28 $32 $36 $3.00 4.0 5.3 6.7 8.0 9.3 10.7 12.0 $4.00 3.0 4.0 5.0 6.0 7.0 8.0 9.0 $5.00 2.4 3.2 4.0 4.8 5.6 6.4 7.2 $6.00 2.0 2.7 3.3 4.0 4.7 5.3 6.0 $7.00 1.8 2.3 2.9 3.4 4.0 4.6 5.1 $8.00 1.5 2.0 2.5 3.0 3.5 4.0 4.5 $9.00 1.3 1.8 2.2 2.7 3.1 3.6 4.0 $10.00 1.2 1.6 2.0 2.4 2.8 3.2 3.6
Disease Management Summary Know your disease package in your wheat variety and corn hybrid Scout for diseases - will help better match fungicide to provide best control Make timely fungicide application(s) when warranted Wheat protect flag leaf, if able wait till bloom Corn tassel to silking (VT-R2) Good coverage and spray volume (15 gal/a ground, 5 gal/a air) When possible, use combination fungicide = multiple MOAs to reduce risk of fungicide resistance developing
Managing Fungicide Use One of the important tools to manage disease Will not cure existing disease symptoms Use best fungicide to manage the specific disease(s) in your field Applications should be based upon: Disease risk Scouting observations Consistent economic benefits are more likely when based upon: Disease risk and Scouting observations
Thank you for your attention! Questions? Heather Kelly youngkelly@utk.edu 731-425-4713