Nectria perithecia and Tubercularia conidia of Coral Spot DiseaseNectria cinnabarina is a weak parasite of hardwood twigs and branches, often attacking through wounds. Early in the year, it produces coral-coloured spots (right) that bleach with age and weathering. This is the conidial (asexual) state of the fungus (= Tubercularia) and is produced on a cushion-shaped (erumpent) stroma called a sporodochium. Later in the year, clusters of dark orange perithecia form on the SAME stromata as the conidia.
Left: perithecia of Nectria develop on old stroma of Tubercularia state. Right: erumpent stroma of the Tubercularia asexual (conidial) state.