Transcript Tomato Diseases - Fusarium and Verticillium Wilts Control

Tomato Diseases
Fungal
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Bacterial
Viral
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
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Bacterial Spot - Xanthomonas campestris pv. vesicatoria
Bacterial Speck - Pseudomonas syringae pv. tomato
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Cucumber Mosaic Virus
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Fusarium Wilt
Fusarium Wilt
Fusarium Wilt
Verticillium Wilt
Tomato Diseases - Fusarium and
Verticillium Wilts - Key Points
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Pathogens: Fusarium oxysporum, Verticillium dahliae,
V. albo-atrum
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Soil-borne pathogens
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Survive in soil for several years
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Plants generally infected through roots
Tomato Diseases - Fusarium and
Verticillium Wilts - Control Strategies
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Rotation (at least 2-3 years)
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VF or VFN resistance
Septoria Leaf Spot
Septoria Leaf Spot
Tomato Diseases - Septoria Leaf Blight
Key Points
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Pathogen: Septoria lycopersici
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Survives over winter on infected plant debris, and also on
equipment, stakes and cages
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Spores dispersed by splashing water (rain, irrigation),
workers or equipment moving through wet plants
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Favored by moist, warm weather
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Symptoms generally appear first on lower leaves
Tomato Diseases - Septoria Leaf Blight
Control Strategies
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Rotation (at least 1-2 years)
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Thorough sanitation of equipment, stakes, etc.
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Stake plants
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Plastic mulches
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Fungicide sprays
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Several effective fungicides available
 Apply at least weekly when weather favorable for
disease
 Good coverage, especially of lower leaves, crucial
 Carefully read label directions
Early Blight
Early Blight
Early Blight
Tomato Diseases - Early Blight
Key Points
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Pathogen: Alternaria solani
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Survives on infected plant debris - partially buried debris is
an excellent source of inoculum
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Spores wind dispersed, can be carried long distances
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Greatest threat of infection:
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Fields with short rotations
 Planting adjacent to fields infected previous year
where debris not completely buried
Infection occurs first on oldest leaves
Tomato Diseases - Early Blight
Control Strategies
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Plant rotation - minimum of at least 2-3 years between
solanaceous crops
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Potato, tomato, weeds in nightshade family
excellent hosts
 Completely bury plant debris after harvest
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Fungicide applications
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Several effective fungicides available
 Carefully read label directions
Provide adequate nitrogen
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Avoid excessive irrigation
Late Blight
Late Blight
Tomato Diseases – Late Blight
Key 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
Tomato Diseases – Late Blight
Key Points
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Source of inoculum:
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Cull piles of infected potatoes or tomatoes
Infected tomato transplants
Infected plants in neighboring fields
Hairy nightshade
Favored by rain, high relative humidity
Control Strategies
 Destroy cull piles, and weed hosts
 Plant disease-free tomato transplants
 Protectant fungicides – several effective fungicides available
Fruit Anthracnose
Fruit Anthracnose
Tomato Diseases - Fruit Anthracnose
Key Points
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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
Tomato Diseases - Fruit Anthracnose
Control Strategies
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Rotation (at least 2 years)
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Weed control (eliminates alternate hosts)
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Stake plants
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Mulches
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Optimum plant spacing
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Remove and destroy infected fruit
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Fungicide sprays
Tomato Diseases - Fruit Anthracnose
Control Strategies
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Fungicide sprays
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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
Bacterial Spot
Bacterial Speck
Bacterial Speck
Tomato Diseases - Bacterial Spot and Speck
Key Points
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Pathogens:
Bacterial speck: Pseudomonas syringae pv. tomato
Bacterial spot: Xanthomonas campestris pv. vesicatoria
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Favored by high humidity, rainfall/irrigation
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Pathogens seed borne
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Dispersal - wind driven rain, clipping plants, equipment
moving between wet plants
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Optimum temperature:
Bacterial speck: 65-75° F
Bacterial Spot: 75-85° F
Tomato Diseases - Bacterial Spot and Speck
Control Strategies
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Clean transplants, pathogen-free seed
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Plant rotation - at least 1-2 years between solanaceous crops
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Thoroughly incorporate plant debris after harvest
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Application of bactericides
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Fixed coppers - alone or in combination with fungicides
Heavy rain, wind-driven rain, hail decrease efficacy
Buckeye Rot
Soil Rot
Tomato Diseases - Soil Rot of Fruit
Key Points
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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
Tomato Diseases - Soil Rot of Fruit
Control Strategies
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mulching around base of plants to avoid fruit contact
with soil helps prevent infection
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mulches include straw, grass clippings, paper,
plastic
staking or caging of plants helps to avoid fruit contact
with soil
Tobacco Mosaic Virus
Tomato Diseases – Tobacco Mosaic
Virus (TMV) - Key Points:
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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
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
Tomato Diseases – Cucumber Mosaic
Virus (CMV) - Key Points:
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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:
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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:
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Eliminate weed hosts – such as
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Milkweed
Chickweed
Ragweed
Clover
White cockle
Carpet weed
Plant a non-host barrier (such as corn) around the tomato
crop
Double Streak Virus
Double Streak Virus
Blossom End Rot
Catface
Growth Cracks
2,4-D Injury
Juglone Toxicity
Juglone Toxicity