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Tomato Diseases | Bacterial Canker Fact Sheets

Bacterial Canker

Symptoms

Bacterial canker infections show a wide range of symptoms and can affect plants at all growth stages. Key diagnostic symptoms are provided for each tissue type.

Stem:

  • Raised pustules on young seedlings
  • Reddish-brown necrotic cankers, especially on older tissue
  • Reddish-brown vascular discoloration, especially at base and nodes

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Images of Bacterial canker on stems of tomato plants (left; center) and stem of a pepper plant (right).

Leaves:

  • Raised pustules on young seedlings
  • Necrotic marginal leaf tissue adjacent to a thin band of chlorotic tissue (firing)
  • On severely infected tissue necrotic lesions with minimal chlorosis may be observed

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Images of Bacterial canker on leaves of tomato plants (left; center) and on a pepper plant (right).

Roots:

  • There are no diagnostic symptoms associated with root tissue

Fruit:

  • Field grown tomatoes – small raised tan colored spots surrounded by a white halo on green and red fruit
  • Greenhouse grown tomatoes – internal web-like appearance

CANKER IMG_1114 50 QUALITY bacterialCanker09-qate87 50 QUALITY bacterialCanker06-1pchyt2 50 QUALITY
Images of Bacterial Canker on tomato fruit (left) and peppers (center; left).

Signs

Bacterial streaming from the margin of a leaf, stem or fruit lesion.

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Often Confused With

  • Bacterial Spot – Look for large crusty lesions on the fruit with no white halo as indicators of bacterial spot.
  • Bacterial Speck – Look for small black pin-point lesions on the fruit with no white halo as indicators of bacterial speck.
  • Early Blight – Look for lesions with concentric rings and chlorosis as indicators of early blight.
  • Mite Damage – Using a dissecting microscope look for live mites on the leaf surface as indicators of mite damage.

comparing diseases 4 canker tomato

Isolation Media

Nutrient Broth Yeast (NBY) (pdf) Extract medium is a non-selective medium used for subculturing suspected clavibacters. Clavibacter michiganensis subsp. michiganensis colonies are yellow, round, entire and convex after 3-5 days at 82 °F.

Yeast extract-dextrose-calcium carbonate (YDC) (pdf) medium is a non-selective medium used for subculturing suspected xanthomonads and clavibacters. Xanthomonas spp. colonies on YDC medium are yellow, mucoid, round, entire and raised after 3 days at 82 °F.

D2ANX medium (pdf) is a semi-selective medium. Colonies grow slowly on D2ANX medium. After 7-10 days at 82 °F, colonies are light-creamy yellow, mucoid, round, entire and raised.

NBY YDC D2ANX

Available Rapid Diagnostic Tests

  • Agdia ImmunoStrip®
  • Agdia ® Enzyme Linked Immunosorbent Assay (ELISA)
  • Envirologix™ DNAble Quick Stix
  • Conventional Polymerase Chain Reaction (PCR) assays
  • Quantitative real time PCR Assay
    • primers RZ ptssk protocol 10/11, probeRZ-ptssk12 PTSSK primers (pdf)

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