Blossom blight and fruit rot. Dense white fungal growth visible on infected flowers and fruits, with dark brown ‘pin-heads’ when the fungus starts to produce spores. Can invade damaged tissues causing water-soaked leaf spots and, on cucurbits, a soft fruit rot. Especially common under wet, warm conditions.
Morphology
Colonies fast growing with abundant mycelium, white, becoming pale yellow. Sporangiophores 1–10 mm tall, 6–12 µm thick, non-septate, unbranched, hyaline, giving rise to up to 12 apical swellings (vesicles) at the top of the sporangiophore. Sporangia arise on short stalks from the apical vesicles at the top of the sporangiophores. The sporangia each contain a single spore but the spores do not readily separate from the sporangium wall and thus remain within the sporangia. In effect, the sporangia appear to be the spores (sporangiospores). The sporangia (‘spores’) are broadly fusiform or ellipsoid, (8–)12–20(–30) µm long, (5–)6–12(–18) µm wide, brown or reddish brown to pale brown, more or less distinctly longitudinally striate, subtended by a short, cylindrical pedicel.
