Diagnosticians

Basic Information | Advanced Information | Diagnostic Information

Tomato Diseases | Bacterial Canker

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

Bacterial Canker 3 bacterialCanker02 bacterialCanker07
Images of bacterial canker on tomato stems (left; center) and a pepper stem (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

bacterialCanker04 Bacterial canker - tomato fruit bacterialCanker08

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

Bacterial Canker 6 bacterialCanker01 bacterialCanker09
Symptoms of bacterial canker on tomato fruit (left; center) and pepper (right).

Signs

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

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.

SpotSpeckBlightMite

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)