LE 3931

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LE 39-31
Signal
Signal transduction pathway
Hypersensitive response
Signal transduction pathway
Acquired resistance
Avirulent pathogen
R-Avr recognition and hypersensitive response
Systemic acquired resistance
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Figure 38-15
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Courtesy of Marc Fuchs, Cornell University, NYSAES
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Zucchini yellow mosaic virus
Cucumber mosaic virus
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Lessons Learned From Successful Crops

• Success of
  Field Crops
• Limited Species Diversity
• Dozens of different lettuce varieties each
  transformation
• requires separate regulatory approval
• Size of Market Matters
• Benefits Benefit per acre Number of acres
• Cost of RD from Discovery to Release gt 100
  million
• Feed grain buyers are farmers comfortable with
  technology
• Fiber crops (cotton) food safety concerns do not
  apply
• Large savings economically and environmentally
• Large potential profits, increasingly
  concentrated industry

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Molecular Plant Breeding Partial
resistance Multiple R genes Strong
environmental effect on IP
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Definitions
VISIBLE SYMPTOMS
INFECTION
SPORULATION
Preventative
Curative
Eradicant Antisporulant

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

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Choice of Application Equipment
Spray coverage is critical for control
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Choice of spray nozzle type
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• Chemigation
• Backflow
• Prevention valve

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Repeated applications of fungicide to protect new
growth
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Application Strategies
Standard weekly application schedule
Concentration of Fungicide on Plant
ED 50
Fungicide Application
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Application Strategies
Rapid plant growth or fungicide washed off by
heavy rain
Concentration of Fungicide on Plant
ED 50
Fungicide Application
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Application Strategies
Fungicide Application Delayed by Weather
Concentration of Fungicide on Plant
ED 50
Fungicide Application
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Snow mold of turfgrass Symptoms in
Spring Fungicides applied during dormant stage
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Dutch Elm Disease Thiabendazole hypophosphite
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Protection of seed and seedlings against
soilborne pathogens

• Pythium
• Phytophthora
• Aphanomyces
• Fusarium spp.
• Rhizoctonia

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Bacterial Spot on TomatoXanthomonas campetris pv
vesicatoria
Seedborne pathogens
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Common Blight BeanXanthomonas campestris pv.
phaseoli

• Source of inoculum
• Seed
• Host residue
• 5 infected seed per acre can result in severe
  epidemic
• Target of seed certification programs
• Western US seed production
• Streptomycin applied to seed

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Smut Disease Cycle - Small Grains
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Ustilago tritici Ustilago hordei embryo
infection
Non infected
Infected
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Bean Pod Mottle VirusBean leaf beetles
controlled by systemic insecticides applied to
seed lower transmission of BPMV
Desmodium Showy Tick Trefoil
Seed Transmission of BPMV
Overwintered beetles
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Choice of Active Ingredient Early Blight of
Potato Control
Foliage Infection
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Grouping Fungicides By Mode of Action
Dow AgroSciences