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Tomato Diagnostic Key
Thomas A. Zitter, Cornell University, Ithaca, NY

Choose the part of the plant showing symptoms (click on the title in the box) or click on the list below

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.



También en Espanol:Guía sinóptica para hoja de tomate

Wilt and General Plant Decline and Crown Area

Tomato Disease Identification Image Key

The renewed interest in growing and sampling of freshly harvested tomatoes has never been greater. Check any garden catalogue and you will find page after page of tomatoes in many colors and sizes. Beefsteak tomatoes still exist, but consumers are discovering or rediscovering heirlooms, grape, cherry, saladette, greenhouse, and not to mention the typical fresh market reds.

Click on photos for enlargement
Heirloom tomatoes represented L to R (some repeated): Brandywine, Goldie, Green Zebra, Cherokee Purple, Cosmonaut Volkov, Great White, Garden Peach, and Striped German.
Heirloom tomatoes
Example of a saladette tomato (Ping Pong)
ping pong tomato
Greenhouse tomatoes
greenhouse tomatoes
Farm fresh reds
farm fresh red tomatoes

Tomatoes and the diseases and disorders that affect them are searched more often than any other commodity covered on the Vegetable MD web site. Hence it was only natural that a Disease Identification Image Key should be developed for use by all parties interested in tomatoes. The key or guide follows a similar layout to the one prepared earlier for diagnosing Cucurbit Diseases. Depending on what part of the plant you have at hand, you can start with leaves, fruit or whole plants and try to arrive at a diagnosis. The diseases and disorders have been arranged in the following order, and have been color coded to aid in knowing which pathogen group your are dealing with:

Bacteria Fungi Pre-Post Harvest Fungal Rots Oomycetes Viruses Viroids Nematodes
Phytoplasma Physiological and Weather Damage from Insects or Insecticides Damage from Herbicides Nutrient Deficiencies Unknowns Parasitic Plants

Thanks to all the contributors, present and past, for making the images available to make the key as useful as possible. If you have any images that you would like to add with your own copyright added, please let me know. (taz1@cornell.edu) I’m sure the worldwide readership would be appreciative.

References with Helpful Color Illustrations of Plant Diseases
Blancard, D. 1994. A Colour Atlas of Tomato Diseases - Observation, Identification and Control. Manson Publishing Ltd., London

Gabor, B., and Wiebe, W. eds. 1997. Tomato Diseases - A practical guide for seedsmen, growers and agricultural advisors. Seminis Vegetable Seeds, Inc. Saticoy, CA.

Howard, R. J., Garland, J. A., and Seaman, W. Lloyd. eds. 1994. Diseases and Pests of Vegetable Crops in Canada. Published by the Canadian Phytopathological Society and Entomological Society of Canada. Ottawa, Canada.

Jones, J. B., Jones, J. P., Stall, R. E., and Zitter, T. A. eds. 1991. Compendium of Tomato Diseases. APS Press, St. Paul, MN. (under revision, available 2008)

Koike, S. T., Gladders, P., and Paulus, A. O. 2007. Vegetable Diseases - A Color Handbook. Academic Press, San Diego, CA.

MacNab, A. A., Sherf, A. F., and Springer, J. K. 1983. Identifying Diseases of Vegetables. The Pennsylvania State University, University Park, PA.

Snowdon, A. L. 1991. A Colour Atlas of Post-Harvest Diseases and Disorders of Fruits and Vegetables. Volume 2: Vegetables. CRC Press Inc. Boca Raton, FL.

References with Good Insect Descriptions and the Damage They Cause
Capinera, J. L. 2001. Handbook of Vegetable Pests. Academic Press, San Diego, CA.

Cranshaw, W. 2004. Garden Insects of North America: The Ultimate Guide to Backyard Bugs. Princeton University Press, Princeton, NJ.

Prepared by T. A. Zitter for web delivery as part of the Vegetable MD web site on April 2007. We gratefully acknowledge the financial support of Cornell Cooperative Extension; Web layout is credited to Dawn Dailey-O'Brien and the studio photographic work of Kent Loeffler is gratefully acknowledged.