Tomato Diseases

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Tomato Diseases

• Fruit Anthracnose - Colletotrichum spp.
• Fusarium Wilt - Fusarium oxysporum
• Verticillium Wilt - Verticillium dahliae, V.
  albo-atrum
• Early Blight - Alternaria solani
• Late Blight - Phytophthora infestans
• Septoria Leaf Blight - Septoria lycopersici
• Soil Rot of Fruit - Rhizoctonia

• Bacterial Spot - Xanthomonas campestris pv.
  vesicatoria
• Bacterial Speck - Pseudomonas syringae pv. tomato

• Cucumber Mosaic Virus

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Fusarium Wilt
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Fusarium Wilt
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Fusarium Wilt
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Verticillium Wilt
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Tomato Diseases - Fusarium and Verticillium Wilts
- Key Points

• Pathogens Fusarium oxysporum, Verticillium
  dahliae, V. albo-atrum
• Soil-borne pathogens
• Survive in soil for several years
• Plants generally infected through roots

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Tomato Diseases - Fusarium and Verticillium Wilts
- Control Strategies

• Rotation (at least 2-3 years)
• VF or VFN resistance

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Septoria Leaf Spot
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Septoria Leaf Spot
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Tomato Diseases - Septoria Leaf BlightKey Points

• Pathogen Septoria lycopersici
• Survives over winter on infected plant debris,
  and also on equipment, stakes and cages
• Spores dispersed by splashing water (rain,
  irrigation), workers or equipment moving through
  wet plants
• Favored by moist, warm weather
• Symptoms generally appear first on lower leaves

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Tomato Diseases - Septoria Leaf BlightControl
Strategies

• Rotation (at least 1-2 years)
• Thorough sanitation of equipment, stakes, etc.
• Stake plants
• Plastic mulches
• Fungicide sprays
• Several effective fungicides available
• Apply at least weekly when weather favorable for
  disease
• Good coverage, especially of lower leaves,
  crucial
• Carefully read label directions

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Early Blight
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Early Blight
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Early Blight
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Tomato Diseases - Early BlightKey Points

• Pathogen Alternaria solani
• Survives on infected plant debris - partially
  buried debris is an excellent source of inoculum
• Spores wind dispersed, can be carried long
  distances
• Greatest threat of infection
• Fields with short rotations
• Planting adjacent to fields infected previous
  year where debris not completely buried
• Infection occurs first on oldest leaves

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Tomato Diseases - Early BlightControl Strategies

• Plant rotation - minimum of at least 2-3 years
  between solanaceous crops
• Potato, tomato, weeds in nightshade family
  excellent hosts
• Completely bury plant debris after harvest
• Fungicide applications
• Several effective fungicides available
• Carefully read label directions
• Provide adequate nitrogen
• Avoid excessive irrigation

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Late Blight
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Late Blight
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Tomato Diseases Late BlightKey Points

• ?Pathogen Phytophthora infestans
• ?Same fungus that causes late blight of potato
• ? Isolates may differ in ability to infect
  potato and tomato
• ? Both mating types (A1 and A2) are now found
  in WI
• ? Symptoms
• ? Lesions on leaves initially water-soaked
  spots with irregular borders
• ? Lesions turn pale green, then brown to almost
  black
• ? White fungal growth appears on underside of
  leaves at border between necrotic and healthy
  tissue
• ? Petiole and stem symptoms similar lead to
  rapid death of plant

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Tomato Diseases Late BlightKey Points

• ? Source of inoculum
• ? Cull piles of infected potatoes or tomatoes
• ? Infected tomato transplants
• ? Infected plants in neighboring fields
• ? Hairy nightshade
• ? Favored by rain, high relative humidity
• Tomato Diseases Late BlightControl Strategies
• ? Destroy cull piles, and weed hosts
• ? Plant disease-free tomato transplants
• ? Protectant fungicides several effective
  fungicides available

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Fruit Anthracnose
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Fruit Anthracnose
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Tomato Diseases - Fruit AnthracnoseKey Points

• Pathogen Several species including
  Colletotrichum coccodes, C. dematium and C.
  gloeosporioides
• Favored by wet weather and warm temperatures
• Survives in soil and plant debris several years
• Spores splashed by rain or irrigation onto
  foliage and fruit
• Ripe or overripe fruit most susceptible, symptoms
  progress rapidly

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Tomato Diseases - Fruit AnthracnoseControl
Strategies

• Rotation (at least 2 years)
• Weed control (eliminates alternate hosts)
• Stake plants
• Mulches
• Optimum plant spacing
• Remove and destroy infected fruit
• Fungicide sprays

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Tomato Diseases - Fruit AnthracnoseControl
Strategies

• Fungicide sprays
• Several effective fungicides available
• Start when first fruit reaches size of a quarter
• Continue weekly until harvest
• Read labels carefully
• Examples of label requirements
• rate of application
• seasonal use limitations - amount / acre / season
• pre-harvest intervals
• crops that can be grown in treated area next year

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Bacterial Spot
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Bacterial Spot
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Bacterial Speck
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Bacterial Speck
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Tomato Diseases - Bacterial Spot and SpeckKey
Points

• Pathogens
• Bacterial speck Pseudomonas syringae pv.
  tomato
• Bacterial spot Xanthomonas campestris pv.
  vesicatoria
• Favored by high humidity, rainfall/irrigation
• Pathogens seed borne
• Dispersal - wind driven rain, clipping plants,
  equipment moving between wet plants
• Optimum temperature
• Bacterial speck 65-75 F Bacterial Spot
  75-85 F

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Tomato Diseases - Bacterial Spot and
SpeckControl Strategies

• Clean transplants, pathogen-free seed
• Plant rotation - at least 1-2 years between
  solanaceous crops
• Thoroughly incorporate plant debris after harvest
• Application of bactericides
• Fixed coppers - alone or in combination with
  fungicides
• Heavy rain, wind-driven rain, hail decrease
  efficacy

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Buckeye Rot
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Soil Rot
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Tomato Diseases - Soil Rot of FruitKey Points

• Pathogen Rhizoctonia solani
• Symptoms
• Rotted tissue showing concentric bands of
  alternating dark and light brown
• Initially, rotted area is firm but becomes mushy
  with invasion of soft rotting organisms
• Affected areas eventually turn black
• Overwinters in soil
• Fungus enters tomato where fruit contacts soil
• Symptoms may not be evident at harvest but can
  develop in storage or shipment

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Tomato Diseases - Soil Rot of FruitControl
Strategies

• mulching around base of plants to avoid fruit
  contact with soil helps prevent infection
• mulches include straw, grass clippings, paper,
  plastic
• staking or caging of plants helps to avoid fruit
  contact with soil

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Tobacco Mosaic Virus
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Tomato Diseases Tobacco Mosaic Virus (TMV) -
Key Points

• Pathogen Tobacco Mosaic Virus
• Symptoms
• Light and dark green mottled areas on leaves
• Necrosis of fruit with some strains
• Stunting of plants depending on growth stage at
  infection
• Virus easily transmitted by workers, machinery
• TMV may be present in tobacco products
• Virus survives on equipment, in plant debris

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Tomato Diseases Tobacco Mosaic Virus (TMV) -
Control Strategies

• Crop rotation minimum of 3 years
• Workers should wash hands in detergent before
  handling plants
• Sanitize pruning equipment periodically
• Use cultivars with TMV resistance

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Cucumber Mosaic Virus
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Tomato Diseases Cucumber Mosaic Virus (CMV) -
Key Points

• Pathogen Cucumber Mosaic Virus
• Symptoms - foliar
• Mosaic or mottle similar to symptoms produced by
  TMV
• Shoestring appearance of leaves (filiform or
  threadlike)
• General stunting of the plant
• Symptoms fruit
• Yield reduction amount and size of fruit
• Fruit often misshapen
• Delay in maturity
• Numerous strains of the virus exist many are
  specific to tomato
• Over 700 plant species are host to this virus
• Usually spread by aphids

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Tomato Diseases Cucumber Mosaic Virus (CMV) -
Control Strategies

• Eliminate weed hosts such as
• Milkweed
• Chickweed
• Ragweed
• Clover
• White cockle
• Carpet weed
• Plant a non-host barrier (such as corn) around
  the tomato crop

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Double Streak Virus
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Double Streak Virus
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Blossom End Rot
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Catface
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Growth Cracks
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2,4-D Injury
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Juglone Toxicity
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Juglone Toxicity