Coral Spot Fungus – Nectria cinnabarina

Fungi of the Week

20th March 2020 | Info

Common name: Coral Spot 

Scientific name: Nectria cinnabarina 

Introduction: The Coral Spot is a pathogenic fungus that is commonly found growing as a saprophyte on dead wood from broadleaf trees.  


Fruiting-body: When young and first forming, the Coral spot has the appearance of minuscule pink blobs/pustules (around the size of a pinhead) that are soft and spongy. Eventually, they begin to harden as the fungus matures and change to a reddish-brown colour.  

Spores/Ascospores: During the spongy conidial stage, asexual spores are produced. Additionally, its ascospores are cylindrical and smooth.  Typically, the spores of a Coral Spot are dispersed by rain and wind.  

Stem: Stemless. 


The Coral Spot mainly forms on Beech trees, but also commonly forms on broadleaf trees such as Sycamore, Horse Chestnut and Hornbeam. They can form all year round but are particularly prevalent in summer and autumn. 

Impact on Trees

The Coral Spot is weakly parasitic but also possess saprobic qualities. Trees that are already weaker through other factors are more likely to be susceptible to the fungus, which can cause the dieback of a tree. Once the coral spot forms (in its spongy stage), it causes dieback to happen on typically the upper foliage and branches of a tree. These pustules that form then break through the thin bark and harden over time causing infected wood to become even weaker and eventually break. 

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