Cereal Killers...Puccinia pathway Stripe Rust Powdery Mildew • Present almost every year •...
Transcript of Cereal Killers...Puccinia pathway Stripe Rust Powdery Mildew • Present almost every year •...
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Cereal Killers:
What you need to know about
controlling small grains
disease
Alyssa Collins
Director, PSU SE Research & Extension Center
Assistant Professor, Plant Pathology & Environmental Microbiology
http://www.extension.psu.eduhttp://www.extension.psu.edu
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Use of fungicides in small grains
• Fungicides can be effective in reducing
some yield-limiting leaf diseases
• Fungicide use is one tool in the approach to
reducing vomitoxin in the harvested product
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Major Wheat Diseases
Rusts
Powdery mildew
Leaf spots
Head scab
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Leaf Rust
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Puccinia pathway
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Stripe Rust
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Powdery Mildew
• Present almost every year
• Environmental conditions determine yield impact (likes cool weather, humidity, high N situations)
• Favored by wheat following wheat or barley, no till
• Some resistant varieties available
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Other leaf diseases
Stagonospora glume blotch (Phaeosphaeria nodorum)
Septoria leaf
Blotch (Septoria tritici)
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• To determine the impact of early, late, and
early + late applications of fungicides on
the overall yield of soft red winter wheat.
• Conducted with grower cooperators in the
PA On-Farm Network, and at SEAREC
Wheat Fungicide & Timing Study
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Wheat Fungicide & Timing Study
Treatments• Untreated Control
• Headline at GS 5, (6 oz/acre)
• Headline GS 5 (3 oz/acre), followed by Twinline GS 9-10 (9oz/acre)
• Twinline GS 9-10 (9 oz/acre)*
• Quilt GS 5 (10.5 oz/acre)
• Quilt GS 5 (10.5 oz/acre), followed by Quilt GS 9-10 (14 oz/acre)
• Quilt GS 9-10 (14 oz/acre)*
Sites: Lebanon Berks York Lancaster Armstrong
Franklin
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*
*
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Effect of Fungicide and Application
Timing on Wheat Yield
83.1
85.7
89.2
90.4
85.7
88.288.4
78.0
80.0
82.0
84.0
86.0
88.0
90.0
92.0
Untreated Headline Early Headlinefollowed by
Twinline
Twinline Late Quilt Early Quilt followedby Quilt
Quilt Late
Bu
sh
els
per
Acre
A
B
AB
AA
A
A
B
Treatments bearing the same letter
are not significantly different at
P=.05
Tukey’s Studentized LSD
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Wheat Fungicide Yield Results
• Disease pressure less than in 2009
• All later fungicide treatments yielded slightly better than untreated control (avg 5.9 bu/A)
• Does not appear to be an advantage to multiple applications, early applications
• At most sites, single late applied strobilurin/triazole mix yielded highest
• Does the yield increase warrant fungicide cost?
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Treatment
Yield
response
Cost of
treatment Average net return per acre
bu/A $/A at $5/bu at $7/buUntreated Control
0.00 0 0.00 0.00
Headline early (6 oz/acre) 2.80 *9.30 to 13.98 0.02 to 4.70 5.62 to 10.31
Headline (3 oz/acre),
followed by Twinline
(9oz/acre) 6.02 *14.91 to 17.25 12.86 to 15.21 24.91 to 27.25
Twinline late (9 oz/acre) 7.29 † 10.26 26.18 40.76
Quilt early (10.5 oz/acre) 0.96 14.49 -9.67 -7.74
Quilt (10.5 oz/acre),
followed by Quilt (14 oz/acre) 4.29 33.81 -12.38 -3.81
Quilt late (14 oz/acre) 4.24 19.32 1.87 10.35
* Range given the maximum $100/gal rebate
† Cheapest effective treatment
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• Leaf diseases significantly lower in
treatments that include a late application
• No differences were observed among
treatments in head scab
Wheat Fungicide Disease Results
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Fungicide economics
Grain price ($/bu) $4 $5 $6 $7 $8 $9 $10
Yield (bu/a) gain to
recoup investment
7.5 6.0 5.0 4.3 3.8 3.3 3.0
Assumes $30/acre based on cost of fungicides and application. Actual cost will vary.
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Does it help to throw in
a fungicide at greenup?
• Fungicide at Feekes 5 followed by a flowering application
• Usually not enough to make it worth it
• Profitability: 1% increase at $3/bu, 3% at $5/bu, and 5% at $7/bu grain priceso Sylvester et al. 2017
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Head scab
• F. graminearum (also causes
Gibberella ear rot of corn)
• Produces mycotoxins
(Deoxynivalenol=vomitoxin)
• Favored by no-till, wheat
following wheat, cool & wet
weather
• Fungus infects through
flowers
• Tends to be worse in wide
row wheat
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Vomitoxin prevention approach
• Select a resistant variety (seriously!)
• Track conditions to target fungicide
applications
• Best variety + Best fungicide = 70%
control
Based on ND Combo trials 03-05
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Management: FHB
• U.S. Wheat
and Barley
Scab Initiative
• Prediction tooI
• www.wheatscab.
psu.edu
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What should I spray?
• Best reduction of scab & DON: Caramba,
Prosaro, Proline
• Some reduction of scab & DON: Tilt, Folicur
• NEVER strobilurins once wheat reaches
boot!
o Headline, Quadris, Evito ALL can increase
DON
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What if it’s going to rain?
• Prosaro/Caramba rainfast within 15-30
minutes
• Bottom line: If the growth stage is right, go
for it even if it’s about to pour
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What if I can’t apply at flowering?
• Good conditions for scab
development = bad
conditions for spraying
• Best time to spray is at
the beginning of flowering
• Can go 4-6 days later and
still get decent control
• Better to go late than
early!
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How long does my fungicide last and
Would it help to spray again?
• Half life of these fungicides is about 7 days
• But scab and DON can continue to
develop after flowering
• Now exploring a Feekes 10.5 Prosaro or
Caramba followed by a generic
tebuconazole 4 days later if weather
conditions persist
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Using a fungicide for Scab prevention• Be prepared to spray when prediction tool forecasts
“medium” to “high” risk for your area
• Start treating within 5-6 days of the start of flowering
• Fungicides applied before flowering do not provide
control
• Wheat that is 5 days or more beyond initial flowering
cannot be treated
• Do not use strobilurins (Headline, Quadris, Twinline, Quilt,
Stratego, etc.) at or after heading (there is evidence that
these chemicals can increase toxin levels)
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Miravis™ (pending EPA approval)
• Syngenta
• Adepidyn™, new chemical group within
carboxamide chemistry (FRAC 7)
• Corn, soybean, wheat, among other crops
• Leaf spots and blights
• Field testing ongoing in multiple states and
environments for Fusarium head blight
(wheat)
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Things to Know for Barley• Barley is not wheat (dif. in flowering
and resistance)
• In barley, some factors that make varieties less susceptible to scab include: o Hulless
o Two-row
o Nodding head types
• Can’t always see barley anthers—spray for scab once heads are emerged
• Barley has a better ability to prevent spread of the fungus following infection than wheat.
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• Be aware that grass forages and cover crops can harbor and serve as an alternate host for many wheat and barley pathogens like Barley Yellow Dwarf Virus and Cephalosporium Stripe.
• A fungicide at flowering for scab will also give you nice control of flag leaf diseases
• Manage your previous crop residue when planting wheat or barley.o Uniform residue = uniform seedling emergence
= uniform tillering and heading time = easier to time fungicide in the spring
Things to Know for Barley
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• Mid-atlantic will probably always be
challenged by DON
• How do we make that work?
• It’s always been about risk management
for farmers, but now we have to teach
maltsters
• Much more research needed, but for
now, moderately resistant varieties is
key
Things to Know for Malting Barley
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Resources
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