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Virus Symptoms You May See

On this page
  • Curly top
  • Alfalfa mosaic virus
  • Tomato spotted wilt
  • Tobacco mosaic tobamoviruses
  • Mosaic virus diseases caused by potyviruses

Outbreaks of virus diseases are unpredictable from year to year and for various geographic locations, the control of these diseases is difficult and not usually practiced. However, if you are able to identify symptom causes, it will help you rule out other pest or nutrient related problems. Use the photos below to identify virus symptoms you may see during the bloom through early fruit growth period. Names link to information on identification and management.

Click on photos to enlarge

Curly top
Curly top
Identification tip: Plants turn yellow to bronze in color with purple-tinged leaves. Plants become stiff and soon die; green fruit turns red, regardless of age.

Alfalfa mosaic virus
Alfalfa mosaic virus
Identification tip: Typical leaf symptoms on plants with alfalfa mosaic include bright yellow blotches with some mottle.

Tomato spotted wilt
Tomato spotted wilt
Identification tip: Plants infected with tomato spotted wilt virus exhibit bronzing of the upper sides of young leaves, which later develop distinct, necrotic spots. Green fruit show slightly raised areas with faint, concentric zones.

Tobacco mosaic tomavirus
Tobacco mosaic tobamoviruses
Identification tip: Symptoms on tomato plants infected with tobacco mosaic viruses vary with the cultivar and the specific virus or strain. A mild mosaic develops on leaves with some leaf malformation, including a fernlike appearance. For fruit symptoms see PMG.

Photo not available.

Mosaic virus diseases caused by potyviruses
Identification tip: Although symptoms vary, plants generally develop an overall lighter coloring and a bushy appearance. Close up symptoms include a mosaic especially on younger leaves. Leaves may be curled. For fruit symptoms see PMG.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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