Symptoms Didymella on melon

• Organs attacked :

• Symptoms :
  • Lack of germination, death of seedlings. Wet, dark spots may develop on cotyledons, stems, and seedling death.
  • Oily to livid leaf spots. Rather circular in shape, they expand as they evolve, take on a brown hue, become necrotic and dry out. Note that they can be located at the edge of the limb initially, and that a yellow halo sometimes surrounds them.
  • First moist and dark green lesions on stems (aerial parts and crown), gradually browning and becoming necrotic (figures 1 to 5). They often start from pruning wounds, grafting or senescent tissue present on the stem and cover large portions of stems.
  • The girdled twigs wither and dry up.
  • Presence of brown, sticky exudates on the stem and fruits (figures 5 and 7).
  • Initially limited, moist and dark lesions on fruits starting from more or less senescent floral parts, at the level of the stylar zone, of micro wounds (peduncular zone). Large lesions can initiate on contact with the ground (Figures 6 and 7). Irregular in shape, they spread and gradually darken. The flesh takes on a blackish tint (figure 8).

•  Signs : Presence of tiny and numerous brown to black globular masses on the lesions. These are the fruiting bodies of this fungus: perithecia and pycnidia visible under a magnifying glass (figures 4 and 9).
• Possible confusion : Note that the phenomenon of "gummosis" is in fact a fairly frequent symptom in Cucurbitaceae which can accompany many phytosanitary problems, but more particularly those linked to fusarium wilt of melon and attacks by D. bryoniae or Macrophomina phaseolina .
• >>> More pictures

• Production areas affected :