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Bacterial spot of tomato and pepper

Quick facts

  • Bacterial spot can be a devastating disease when the weather is warm and humid.
  • The disease can affect all above-ground parts of tomato and pepper plants: stems, petioles, leaves, and fruits.
  • Fruit spots commonly result in unmarketable fruit, not only for fresh market but also for processing because the spots make the fruit difficult to peel.

Pathogen

Four closely related bacteria: Xanthomonas vesicatoria, X. euvesicatoria, X. gardneri, and X. perforans.

Host range

Different strains infect either tomato, pepper or both crops.

 

Tomato fruit infected with bacterial spot
Tomato fruit infected with bacterial spot
Bacterial spot on tomato leaves
Bacterial spot on tomato leaves

Identification

Signs and symptoms

  • Tomato leaves have small (<1/8 inch), brown, circular spots surrounded by a yellow halo.
    • The center of the leaf spots often falls out resulting in small holes.
  • Pepper leaves have small (<1/8 inch), brown, circular spots that do not have a yellow halo and centers do not fall out.
  • Small, brown, circular spots may also occur on stems and the fruit calyx.
  • Fruit spots are ¼ inch, slightly raised, brown and scabby.
    • Tomato fruit often have a waxy white halo surrounding the fruit spot.
    • Pepper fruit spots often occur on the stem-end of the fruit.
  • Spots occur on green and red fruit but do not result in rot.

Environment

  • High temperatures (75°F to 86°F)
  • High humidity
  • Frequent rainfall/overhead irrigation
Bacterial spot on pepper leaves
Bacterial spot on pepper leaves
Small green pepper with spots
Pepper infected with bacterial spot

Biology and disease cycle

  • Bacteria survive on plant debris in the soil for one to two years, but will not survive once plant debris is broken down.
  • Introduction is primarily on infected seed or infected transplants. Even seedlings that do not show symptoms may be infected and will show symptoms later in the growing season.
  • Bacteria can spread from plant to plant by tools, workers’ hands, or through splashing rain or irrigation water.
  • Between rotations, the bacteria may survive on tomato or pepper volunteer plants.

Management

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Anna Johnson, Michelle Grabowski, Extension educator and Angela Orshinsky, Extension plant pathologist

Reviewed in 2016

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