Healthy Plants

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Late blight on tomato
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nahG SA-hydroxylase gene
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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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Choice of Active Ingredient Early Blight of
Potato Control
Foliage Infection
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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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Grouping Fungicides By Mode of Action
Dow AgroSciences
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Protectant Fungicide - Inorganic
Multisite inhibitor Prevents spore
germination Broad spectrum Organometallic/fixed
copper Used on wide array of crops Sold as
Kocide, Champ
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Protectant Fungicide - Organic
Multisite inhibitor Broad spectrum Used on wide
array of crops Sold as Dithane, Manzate,
Penncozeb
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Protectant Fungicide - Organic
Inhibits sulfur-containing enzymes Used on many
vegetable crops Sold as Bravo, Echo, Equus
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Curative Fungicide - Organic
Inhibition of mitosis Single site of action Used
as seed, foliar, stem and postharvest treatment
Resistance risk is high Sold as Mertect
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Protectant and Curative Fungicide

Registered for many plant species Seed and soil
application Systemic activity Preventive and
curative
Site specific disrupts RNA synthesis Some
pathogens are resistant All 0omycetes except
Aphanomyces Product names Soil Foliage
Ridomil, Subdue 2E Seed Allegiance, Apron
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Model of fumigant movement
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INJECTION INTO BEDDED ROW
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INJECTION INTO BEDDED ROW ONTARIO
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YIELD AND QUALITY
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Metam sodium fumigation
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Heartland farm fumigation fall 05
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Heartland farm fumigation fall 05
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Warton et al. 2001, Biodegradation of metham Na
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Warton et al. 2001, Biodegradation of metham Na
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Ref Verhagen et.al. 1996
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nondegrading soil
biodegrading soil
Warton et al. 2003
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Lettuce seed bioassay for detecting metham sodium
in soil following fumigation
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Lettuce seed bioassay for metam sodium after 9
days
Fumigated 7 times, pH 6.5
Fumigated 1 time, pH 5.7
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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