Plant Disease Management Handbook

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Greenhouse Plants, Ornamental - Impatiens Necrotic Spot

Image related to Tomato (Lycopersicon esculentum)-Tomato Spotted Wilt

Note the ring pattern all over this fruit.

Photo part of OSU Extension Plant Pathology Slide

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Tomato (Solanum lycopersicum) - Varietal Resistance

Greenhouse Plants, Tomato - Common Mosaic of Tomato (Internal Browning of Fruit)

Image related to Tomato (Lycopersicon esculentum)-Common Mosaic of Tomato (Internal Browning of Fruit)

Tomato plant exhibiting symptoms of TMV.

Image by OSU Plant Clinic, 2013.

Cause Tomato big bud has been reported in California and other regions. It is caused by a phytoplasma that is spread by leafhoppers, and the specific phytoplasma involved depends on the region. In California, the disease is caused by the beet leafhopper-transmitted virescence agent. The disease is rare on tomato but also occurs on celery, radish, and Chinese cabbage. The phytoplasma overwinters on weeds or other crop hosts. The disease follows the leafhopper migration.

Image related to Tomato (Lycopersicon esculentum)-Aster Yellows

We assume the plant on the left is infected.

OSU Extension Plant Pathology Slide Collection, 19

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Greenhouse Plants, Tomato - Powdery Mildew

Powdery mildew colonies can occur on fruit stems as well as leaves.

Jay W. Pscheidt, 2020.

Some powdery mildew fungi can produce profuse white powdery growth on the upper leaf surface as seen here while others may only be seen as a sparse growth on the leaf's lower side.

Jay W. Pscheidt, 2020.

Powdery mildew colonies on the underside of a tomato leaflet.

Photo by Cynthia M. Ocamb, 2020.

A tomato plant with a large number of discrete powdery mildew colonies on the leaves.

Photo by Cynthia M. Ocamb, 2019.

Powdery mildew colonizing extensively the stems, petioles, and leaflets of an affected plant. Note the whitish cast on the stems and petioles.

Photo by Cynthia M. Ocamb, 2016.

Powdery mildew heavily colonizing on a tomato plant and causing the affected leaflets to turn brown and die.

Photo by Cynthia M. Ocamb, 2016.

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Tomato (Solanum lycopersicum) - Varietal Resistance

Galls on roots are due to nematode and not bacteria.

Herald Jensen.

Image related to Tomato (Lycopersicon esculentum)-Nematode, Root-knot

Note the numerous galls or knots along the roots.

Photo by R. H. Henderson, 1976.

Lots of tomato roots knotted up with a lawn background.

Kathy Merrifield, 1987.

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Potato (Solanum tuberosum) - Late Blight

Image related to Tomato (Lycopersicon esculentum)-Late Blight

Close-up of a leaf with late blight. The whitish fungal growth is characteristic. Look for it early-morning while the relative humidity is high.

Photo by Mary Powelson.

Note the lesions on the leaves.

Photo by Cynthia M. Ocamb, 1998

Stems and fruit show evidence of late blight.

Photo by Cynthia M. Ocamb, 1998.

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Greenhouse Plants, Tomato - Gray Mold

Image related to Tomato (Lycopersicon esculentum)-Gray Mold (Ghost Spot)

Faint, pale halos appear white on immature fruit, yellow on ripe fruit.

OSU Extension Plant Pathology slide

A tomato with Botrytis (cause of gray mold) infecting the stem.

Cathy Turner (University of Alaska), 2007.

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Potato (Solanum tuberosum) - Early Blight

Image related to Tomato (Lycopersicon esculentum)-Early Blight

Note not only necrotic areas of fruit but also leaf spots.

Photo by Kathy Merrifield, 1990.

See:

Tomato (Solanum lycopersicum) - Common Mosaic of Tomato (Internal Browning of Fruit)

Cause A combination of tobacco mosaic virus and potato virus X. Workers or equipment mechanically transmit this disease. Virus strains, plant age, and day length influence symptom severity.

Cause Fungi or fungus-like microorganisms, including Pythium aphanidermatum, P. debaryanum, P. myriotylum, Globisporangium ultimum (formerly P.