Healthy on the left and Botrytis blight on the right.
Jay W. Pscheidt, 2019.
Sporulation of Botrytis on spent flowers.
Water soaked and necrotic spots on petals before collapse due to Botrytis blight.
Senescent leaves can also be attacked and become a source of spores.
See:
Greenhouse Plants, Ornamental - Gray Mold