Soybean Rust

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Soybean Rust

• Chemical Control
• Fungicides

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Crop Management Strategies to Control Rust

• ELIMINATE OVERWINTERING HOSTS.
• Not practical
• Cultural Practices ????.
• SCOUT FOR RUST CONTINUOUSLY.
• APPLY FUNGICIDES.
• SOYBEAN VARIETY SELECTION.

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Day 1
Day 6
Day 13
Day 27
Speed of action is critical
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Fully Registered FungicidesSection 3Active
ingredients and Products

• Chlorothalonil
• Echo 720
• Bravo Weather Stik
• Protectant activity
• Chlorothalonil group

• Azoxystrobin
• Quadris
• Pyraclostrobin
• Headline
• Protectant activity
• Strobilurin group

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Section 18 ApprovedActive ingredients and
ProductsTriazole Group

• Propiconazole
• Tilt
• PropiMax
• Bumper
• Tebuconazole
• Folicur
• Curative activity

• Myclobutanil
• Laredo 25 EC
• Laredo 25 EW
• Curative activity

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• What are the ideal properties for a soybean rust
  fungicide?

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The ideal properties for a soybean rust fungicide
Fungicide
No Fungicide

• Persistent preventative effect
• Good curative activity
• Rapid movement to site of infection and underside
  of leaf
• Remain where applied to prevent subsequent
  infection from incoming spores
• Movement to protect new growth
• Built-in resistance management
• Excellent activity against other soybean diseases
• Yield benefits to justify treatment

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Spores Formed in Pustules
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Soybean Rust Lesion Types and Characteristics of
Early Symptoms of Soybean Rust and Bacterial
Pustules
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(Poppler, 2004)
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Soybean RustEpidemiology

• Optimum growth potential at 15-28 C
• Germination and initial infection requires free
  moisture for 6-12 h
• Direct penetration of leaf epidermal cells by
  urediniospores
• New uredinia are visible in 5-8 days under ideal
  conditions
• Urediniospore production can start 9 days after
  infection and continue for 3-4 weeks
• Marginal uredia can continue forming for 8 weeks
  following initial infection
• More than 400 lesions possible on heavily
  infested soybean leaves

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Fungicide Terms

• Protectant (preventative)
• Barrier between leaf surface and rust spores
• Curative
• Kills pathogen after early infection
• Systemic
• Locally systemic
• Translaminar

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Definitions
VISIBLE SYMPTOMS
INFECTION
SPORULATION
Preventative
Curative
Eradicant Antisporulant

• Preventative
• Preventing the establishment of infection
• Curative
• Inhibiting the development of an
  established infection which is not showing
  visible symptoms

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Effects on rust fungal development

Spore germination
Mycelial growth
Pre- sporulation
Penetration
Sporulation
Bravo
Triazoles
Azoxystrobin
Highly effective
Little or no effect
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Fungicide applied to Specific area of
leaf Pathogen applied to entire leaf
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Preventive Activity
Fungicide
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Curative Fungicide
Untreated
Fungicide
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Sprayed
Sprayed
Not Sprayed
Fungicides Control Soybean Rust
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Fungicide Websites

• www.plantpath.wisc.edu/soyhealth
• www.ncpmc.org/soybeanrust/
• www.planthealth.info/rust/rust.htm
• www.plantpath.iastate.edu/soybeanrust.html
• www.oardc.ohio-state.edu/ohiofieldcropdisease/soyb
  eans/soybean_rust.htm
• http//www.ppdl.purdue.edu/ppdl/SBR/SBR_fungicide.
  htm