Symptoms on Cucurbitaceae

• Organs attacked :

• Symptoms :
  • Moist, brownish to orange lesions, invading and altering the inside of the stem, and numerous cavities linked to local liquefaction of the internal tissues (figure 1).
  • Browning of the outside of the stem, a dark brown to blackish lesion extending and eventually encircling it over a more or less significant length.
  • Decomposition and liquefaction of all stem tissues, only the vascular system remaining.
  • Leaf yellowing and wilting,  collapse of plants which eventually die (figures 2 and 3).
  • Damp, blackish lesion spots on leaves, more or less surrounded by a large chlorotic halo. Sections of the petioles are sometimes surrounded by wet rot (figure 4) causing the leaves to dry out.
  • Wet rot on rapidly developing fruits . Moist, soft tissues show a dark brown to blackish tint (Figure 5). It preferentially initiates from the stylar scar. The fruits can completely liquefy (Figure 6).

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• Signs : altered tissues often give off an unpleasant odor; sometimes presence of a milky mucus on certain organs.
• Possible confusion :

• Production areas affected :

•  Pectobacterium spp. reported on Cucurbitaceae : Dickeya chrysanthemi (Burkholder et al. ) Samson et al. ( Pectobacterium chrysanthemi [Burkholder et al. ] Brenner et al. , E. chrysanthemi Burkholder et al. ) mainly affecting stems or fruits; Erwinia tracheiphila (Smith) Bergey et al. responsible for bacterial wilt of Cucurbitaceae.