Notes

Outline

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

Fusarium Wilt

Fusarium Wilt

Fusarium Wilt

Verticillium Wilt

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

Tomato Diseases - Fusarium and Verticillium Wilts - Control Strategies Rotation (at least 2-3 years) VF or VFN resistance

Septoria Leaf Spot

Septoria Leaf Spot

Tomato Diseases - Septoria Leaf Blight Key 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

Tomato Diseases - Septoria Leaf Blight Control 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

Early Blight

Early Blight

Early Blight

Tomato Diseases - Early Blight Key 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

Tomato Diseases - Early Blight Control 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

Late Blight

Late Blight

Tomato Diseases – Late Blight Key Points 8Pathogen:  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 8 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 8 Source of inoculum: ! Cull piles of infected potatoes or tomatoes ! Infected tomato transplants ! Infected plants in neighboring fields ! Hairy nightshade 8 Favored by rain, high relative humidity Tomato Diseases – Late Blight Control Strategies 8 Destroy cull piles, and weed hosts 8 Plant disease-free tomato transplants 8 Protectant fungicides – several effective fungicides available

Fruit Anthracnose

Fruit Anthracnose

Tomato Diseases - Fruit Anthracnose Key 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

Tomato Diseases - Fruit Anthracnose Control Strategies Rotation (at least 2 years) Weed control (eliminates alternate hosts) Stake plants Mulches Optimum plant spacing Remove and destroy infected fruit Fungicide sprays

Tomato Diseases - Fruit Anthracnose Control 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

Bacterial Spot

Bacterial Spot

Bacterial Speck

Bacterial Speck

Tomato Diseases - Bacterial Spot and Speck Key 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

Tomato Diseases - Bacterial Spot and Speck Control 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

Buckeye Rot

Soil Rot

Tomato Diseases - Soil Rot of Fruit Key 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

Tomato Diseases - Soil Rot of Fruit Control 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

Tobacco Mosaic Virus

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

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

Cucumber Mosaic Virus

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

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

Double Streak Virus

Double Streak Virus

Blossom End Rot

Catface

Growth Cracks

2,4-D Injury

Juglone Toxicity

Juglone Toxicity