Stems and flowers become covered with a velvety brownish-grey, fungal growth.
A very common fungus which produces spores that are always in the air. They attack plants through areas of damage.
At first, small pale brown or white patches appear and the flowers start to rot.
Controlling this fungus is very difficult because it is so widespread. Affected areas must be cut out and disposed of or burnt. At the first signs of attack, treat with a fungicide.