Didymella curtisii - Red plotch, red leaf spot

Didymella curtisii is a fungal disease sometimes referred to as red blotch, red leaf spot, or red fire that displays itself with bright-red patches affecting any part of the plant from roots to flowers. It is most active in cool damp weather and spread by air-borne spores. Even treated plants can be rapidly reinfected so it is best handled by preventative measures such as avoiding these conditions by providing ventilation and not watering at these times.