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Tomato  Disease  Identification  Key By Affected Plant Part: Fruit Symptoms
Tomato plant drawing

Generalized tomato plant adapted from Plant Pathology 4th edition by G. N. Agrios copyright 1997 as Figure 1-1 published by Academic Press, San Diego, CA, with permission from Elsevier.

Fruit Symptoms by Pathogen Group or Other Causes








Pre-Post Harvest Rots


Damage From:

Fruit Symptoms By Location and Size of Lesion

Top and Shoulder

Very small specks or lesions 1/8-1/4 in diameter, raised or sunken or imbedded
bacterial speck on tomato Bacterial spot bacterial canker target spot on tomato fruit black mold (Alternaria) alfalfa mosaic cloudy spot lygus bug damage

Bacterial speck

tiny black spots; sometimes raised or imbedded  

Bacterial spot

small, brown, scabby, sunken or slightly raised spots

Bacterial canker

white, raised, corky spots; the brown center “birdseye” fruit symptoms do not always occur, like in greenhouses

Target spot

dark brown sunken spots enlarge with cracked centers

Black mold (Alternaria alternata)

infection commonly follows damage, as seen with plant bug feeding

Alfalfa mosaic virus

sunken irregular shaped spots following systemic infection

Cloudy spot (caused by Stinkbugs feeding injury)

yellow to whitish spots of irregular size; white spongy tissue extends into flesh

Lygus plant bug feeding injury

windowpane-like feeding damage; can allow establishment of secondary pathogens

Lesions large, sunken

Anthracnose on tomato late blight hail injury buckeye yellow shoulder


circular sunken spots; dark center; mature fruit; common 

Late blight

large, firm, greasy, rough, brown spots; distinct edge; sporulation may occur 

Hail injury

irregularly shaped sunken lesions

Buckeye rot 

large, firm, smooth, brown spots; concentric zones 

Yellow/green shoulder

area affected is exposed to sun, and chlorophyll fails to change as fruit matures

Stem End

Lesions large and some associated at or near calyx
gray mold on tomato white mold early blight concentric rings radial rings rain (weather) check thrips damage

Gray mold 

soft rot; skin breaks; gray fuzzy fungal growth; white rings

White mold (timber rot) 

gray watery rot; rapid collapse; white mold may contain black, pea-like objects (sclerotia)

Early blight

dark brown to black, leathery, sunken spots; concentric rings; at stem end

Concentric rings

splitting of epidermis in circular rings, resulting from changing environmental conditions involving moisture

Radial rings

splitting of epidermis radiating from the calyx to blossom end; fluctuating environmental conditions involving moisture.

Weather checking

small cracks in the cuticle may enlarge considerably if presence of water (mist, fog, dew) exists for extended periods of time; fungi may invade


mouthparts pierce the cuticle causing the damage while removing plant sap

pythium sour rot trichothecium rot hornworm damage

Pythium rot

starts as small water-soaked lesion from contact or in proximity with soil; white, cottony, aseptate mycelium soon develops and fruit becomes watery

Sour rot (Geotrichum)

rot begins at stem scar followed by whitish fungal growth; can occur on mature green and ripe tomatoes; a sour odor is evident


white fungal growth occurring near calyx


feeding damage on shoulder or near calyx

Blossom End

Usually large in size
buckeye rot blossom end rot on tomato catface rhizoctonia

Buckeye rot 

large, firm, smooth, brown spots; concentric zones

Blossom-end rot

dark brown to black, leathery spot at blossom end


dark brown firm streaks (scars) at blossom end

Rhizoctonia soil rot

usually occurs on ripening fruit on or in close proximity to soil; initially firm, but becomes a watery rot

Calyx to Blossom End

glyphosate damage powdery mildew septoria

Glyphosate injury

symptoms mimicking catface-like symptoms

Powdery mildew (Oidium)-does not directly infect fruit(shown here on calyx)

powdery growth on individual sepals of calyx; not directly infecting fruit

Septoria leaf spot

dark brown lesions on sepals of calyx; not directly infecting fruit

Entire Fruit

tobacco mosaic virus potato leafroll virus cucumber mosaic virus tomato spotted wilt virus tobacco etch virus single streak virus tobacco mosaic & potato virus X

Tobacco (Tomato) mosaic virus

fruit symptoms will vary depending on virus strain, and how long the plant has been infected

Potato leafroll virus

puffiness associated with systemic infection with PLRV; other puffiness caused by environmental conditions

Cucumber mosaic virus

CMV infections do not normally cause fruit infection; illustrations from Mediterranean region (Italy)

Tomato spotted wilt virus  

initially small irregular brown spots; brown ring spots; mottling; blotches

Tobacco etch virus

dark green blotches following infection at an early age

Tobacco mosaic virus single streak

TMV symptoms associated with a specific strain

Tobacco mosaic & potato virus X-double streak

firm dark blotches appearing on most of fruit surface

plant macho big bud sunscald puffiness weather checking Zippering broad mite damage on pepper fruit

Tomato planta macho

reduced size and irregular ripening associated with viroid infection

Big bud

fruit distortion and irregular ripening


usually seen as whitish area developing on shoulder exposed to direct sunlight


irregular fruit shape and empty locules; associated with environmental conditions

Weather checking

small cracks in the cuticle may enlarge considerably if presence of water (mist, fog, dew) exists for extended periods of time; fungi may invade


a thin longitudinal scar extends from the stem scar to the blossom end; occasionally an open hole to the locule forms; defect happens when the flower anthers fuse to the ovary wall of developing fruit and occurs most commonly when fruit set takes place in cool weather

Broad mite
irregular rippening graywall Unknowns spray mixture damage

Irregular ripening (whitefly)

irregular ripening of fruit resulting from heavy whitefly occurrence on plant

Gray wall (GW)

typically develops on green fruit prior to harvest; appears as black to dark brown necrotic tissue in the walls of the fruit; TobMV, TomMV have been implicated in some cases of GW, but plants free of virus and those resistant to virus also develop GW


Spray Mixture Damage
(Difolatan & sevin & parathion)

irregularly shaped sunken spots with defined black border and beige centers follow pesticides applied as a mixture