Biology epidemiology

• Conservation, sources d'inoculum

C. cucurbitarum has abilities saprophytic high and a large enzymatic arsenal which allow it to degrade a large number of substrates, plant debris and to persist in soils from year to year. It is also very polyphagous as we have indicated previously and is found on a great diversity of hosts ensuring its multiplication and its conservation.

Its chlamydospores and zygospores in particular allow it to survive.

• Penetration, invasion

It is an opportunistic fungus which settles on Cucurbitaceae in particular from senescent floral organs . For example, the wilted corollas, which persist longer than usual in humid periods, constitute nutritive bases allowing them first to settle and then secondly to colonize the fruits and cause them to rot. Stamens and pistils can also be colonized.
It can also penetrate the fruit through a wide variety of injuries: sunburn , apical necrosis , coulure , insect bites, various shocks, etc.)

• Sporulation and dissemination
  

This fungus often fruits abundantly on rotten fruit (Figure 1). The numerous spores produced (figures 2 to 4) are disseminated by wind, rain and sprinkler irrigation causing ( splashing, projections of soil particles). Certain insects are said to be "vectors" of C. cucurbitarum .

• Conditions favorable to its development

Its damage is particularly serious following heavy rains. The free water present on the fruits is very conducive to its development.

C. cucurbitarum settles preferentially on weakened hosts and via "nutrient bases" or wounds. It appreciates hot and humid climates and thrives particularly well at temperatures of 25 ° C and above.