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Tomato Diseases | Tomato Mosaic

Tomato Mosaic

Descriptions of Plant Viruses Website provides extensive information about viruses, viroids, and more including descriptions, taxonomic notes, and sequence analyses.

Symptoms

Foliage:

  • Alternating light and dark green coloring between yellowing leaf veins.
  • Leaves curl and become “fern-like” (filiform) or pointed in appearance.
  • Yellow streaking or spotting appears until leaves are completely yellow, or chlorotic.
  • Newer growth is deformed and distorted.

Fruit:

  • Brown spots or blotchy discolored areas may appear on the outside of fruits.
  • When infection is severe, the fruit appear distorted or deformed with non-uniform fruit color.
  • Plants may also be stunted and yield a low quantity of fruit.

Signs

Tobacco mosaic virus can be seen in tomato sap (leaf dip assay) as a rigid rod-shaped virus particle measuring about 300 nm by 15 nm by electron microscopy.

Often Confused With

  • Herbicide Damage – Herbicide damage on tomato plants consists of the curling, folding, and twisting of foliage.  Leaves also become chlorotic, especially in the veins, and in some cases, develop necrosis as well.  If fruits are damage, they will be irregularly shaped.
  • Tobacco Etch Virus and Potato Virus Y – Light and dark green mosaic develops on the leaves that eventually curl and distort.  This occurs mostly on younger and new leaves.  Fruit also becomes infected and has internal browning and uneven ripening.  However, these viruses are different from tobacco mosaic virus because they are vectored by aphids.

Indicator Plant Bioassay

Comparative host range tests were performed in the publication  Castello et. al. 1992 (pdf) with sap from Lilac infected with Tomato mosaic virus.   Local necrotic lesions developed on Nicotiana glutinosa, local chlorotic lesions developed on Beta vulgaris and Chenopodium quinoa, and systemic mottling and mosaic developed in Nicotiana tabacum cvs. Xanthi and Lycopersicon esculentum Mill. cvs. Burpeeana Early, Super Beefsteak, and Red Cherry when infected with ToMV.

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