Main symptoms

Choanephora cucurbitarum causes rots on the flowers and subsequently on the fruits of Cucurbitaceae.  These are often moist and located at the tips of the fruits (Figure 1). Affected tissues, moist and soft ,. The fruits can completely liquefy in a few days.

Wet, soft lesions spreading rapidly on mature fruits, often from their stylar (Figure 1) or stalk ends, or even wounds. Affected tissues take on a translucent appearance and dark tint, liquefy and eventually collapse. Juice flows may be observed.

The mycelium of the fungus invades the tissues, and a whitish to greyish mold subsequently covers them (Figure 2). It is made up of the mycelium, sporocystophores and sporocysts of this zygomycete. In the long term, numerous rather aerial fruiting bodies, in “black pinheads”, are visible on the damaged tissues (figure 2).

Care should be taken not to confuse this mold with that produced by a neighboring fungus, Choanephora cucurbitarum , which causes quite similar symptoms on the fruits of Cucurbitaceae.