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Common Tomato Diseases and Disorders

Diseases

Late Blight—Phytophthora infestans

** Late Blight is a very serious disease. If you suspect Late Blight in your garden, please contact the University of Maine Cooperative Extension, Pest Management Office at 800-287-0279 **

tomatoes showing symptoms of late blight tomato leaves showing symptoms of late blight tomato stem with symptoms of late blight
Brown, leathery spots on the top and sides of fruit. In humid conditions, white mold also forms. Spots start out pale green, usually near the edges of tips, then turn brown to purplish-black. In humid conditions a fuzzy mold appears on the undersides of leaves. Black and brown spots appear and spread. In high humidity, entire vines can be killed very quickly.

Early Blight—Alternaria solani

tomato showing symptoms of early blight tomato leaf showing symptoms of early blight tomato stem with symptoms of early blight
Dark, sunken spots on the stem end of fruits. One or two spots per leaf, each ¼ to ½ inch diameter. Spots have tan centers with concentric rings and yellow halos. Dark, sunken cankers at or above the soil line.

Anthracnose—Colletotrichum coccodes

tomatoes with symptoms of anthracnose tomato with symptoms of anthracnose tomato with symptoms of anthracnose
Depressed, circular lesions up to 5 inches in diameter on ripe fruit. As lesions mature, they develop concentric rings and become dotted with small black specks. In moist weather, masses of salmon-colored spores may form on the lesion surface.

Bacterial Spot—Xanthomonas campestris

tomato with symptoms of bacterial spot tomato plant with symptoms of bacterial spot tomato leaf with symptoms of bacterial spot
Fruit lesions start as tiny raised blisters. Lesions increase in size and become brown and scab-like. On leaves, stems and fruits, brown circular lesions, less than 1/10 inch in diameter.

Bacterial Canker—Clavibacter michiganensis

tomatoes with symptoms of bacterial canker tomato plant with symptoms of bacterial canker tomato stem with symptoms of bacterial canker
Distinctive spots are white and slightly raised initially, then raised with dark-colored center and white halos, each about 1/16 inch in diameter. The white halo later turns brown. Leaflets begin to turn brown at the edges, then die back progressively toward the leaf midrib. Often only one side of a plant is affected at first, but symptoms eventually spread.

Tomato Leaf Spot—Septoria lycopersici

tomato plant with symptoms of tomato leaf spot tomatoe leaves with symptoms of tomato leaf spot tomatoe leaves with symptoms of tomato leaf spot
Fruit is not affected, although sunscald can be a problem due to foliage loss. Numerous brown spots on leaves, each about 1/16 inch in diameter. They do not have a yellow halo and they do have black specks in the center. First symptoms are usually on lower leaves after the first fruit sets. Disease spreads from oldest to youngest growth.

White Mold (Sclerotinia stem rot)—Sclerotinia sclerotiorum

tomato plant with symptoms of white mold (sclerotinia stem rot) tomato stem with symptoms of white mold (sclerotinia stem rot) tomato stem with symptoms of white mold (sclerotinia stem rot)
Fruit is not affected. Infected stems are soft with a light gray bleached appearance. White mold appears on plants during flowering. Hard, black sclerotia with white interiors form inside stems.

Physiological

Blossom End Rot

tomato with symptoms of blossom end rot tomatoes with symptoms of blossom end rot tomatoes with symptoms of blossom end rot
First appears as a sunken, brownish black spot ½ to 1 inch in diameter at the blossom end of the fruit. Spots gradually increase in size. Blossom end rot is caused by a calcium deficiency related to fluctuations in available moisture.

Sunscald

tomato with sympstoms of sunscald tomatoes showing symptoms of sunscald tomatoes showing symptoms of sunscald
Occurs on green tomato fruit exposed to the sun. Initially a whitish shiny area, the bleached tissues gradually collapse, forming a slightly sunken area that may become pale yellowish and wrinkled as the fruit ripens. The killed tissue is invaded by secondary organisms which cause the fruit to decay.

Catfacing

tomatoes with catfacing tomato with catfacing tomato with catfacing
Misshapen fruit with irregular bulges at the blossom end and bands of leathery scar tissue. Catfacing is caused by cold weather at the time of blossom set. Catfacing is most common in the large-fruited "beefsteak" type tomatoes.

Fruit Cracking

tomatowes with concentric cracking tomato with radial cracking tomato with concentric cracking
Cracking is due to rapid fruit development and wide fluctuations in water availablity. Radial growth cracks radiate from the stem. Concentric cracks encircle the fruit, usually on the shoulders.

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Identification and Control Information (each will open in a new window)

Late Blight

Early Blight

Anthracnose

Bacterial Spot and Bacterial Canker

Tomato Leaf Spot (Septoria)

White Mold

Blossom End Rot

Sunscald

Catfacing

 

Didn't find what you were looking for? More Help with Disease Identification
Want to Know More? More Information About Healthy Gardens

 

 

[Photos, left to right: Robert Wick, University of Massachusetts, Bugwood.org; Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org; Department of Horticulture Website at Cornell University; Yuan-Min Shen, Taichung District Agricultural Research and Extension Station, Bugwood.org; Clemson University - USDA Cooperative Extension Slide Series, , Bugwood.org; Clemson University - USDA Cooperative Extension Slide Series, , Bugwood.org; USDA; Clemson University - USDA Cooperative Extension Slide Series, , Bugwood.org; Apsnet.org; Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org; Ufl.edu; Clemson University - USDA Cooperative Extension Slide Series, , Bugwood.org; Heinz USA Archive, , Bugwood.org; Heinz USA Archive, , Bugwood.org; UMass Extension; MU Extension Plant Diagnostic Clinic; William M. Brown Jr., , Bugwood.org; ISU Plant Disease Clinic; Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org; Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org; Iowa State University Extension; Tim Coolong, University of Kentucky;  ; Patrick Byers, MU Extension; Howard F. Schwartz, Colorado State University, Bugwood.org; Queen's Printer for Ontario, 2009; Queen's Printer for Ontario, 2009; M.E. Bartolo, , Bugwood.org; Queen's Printer for Ontario, 2009;  ; Univ of California Extension; Texas AgriLife Extension Service, Texas A&M System; Paul Bachi, University of Kentucky Research & Education Center, Bugwood.org ]

 
It is the policy of the State of Maine to minimize reliance on pesticides. The Maine Department of Agriculture and the Maine IPM Council encourage everyone to practice integrated pest management and to use pesticides only as a last resort. The mention of pesticides in the fact sheets linked to these pages does not imply an endorsement of any product. Be sure that any product used is currently registered and follow all label directions.