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Cytospora chrysosperma

Cytospora canker C. chrysosperma

Description

In the picture are tendrils of conidiospores that were formed in 1-2 mm wide pycnidia under the bark. Such tendrils are formed by several fungi, in the given case it was Cytospora chrysosperma whose sexual stage is Valsa sordida. The fungus is a weak pathogen and it causes damage only if a host plant was in unfavourable soil and weather conditions before. Necrotized tissue is sunken, the tree can die back within 2-3 years from infection. The tendrils of spores are formed in lines, when wood is moist (not wet). They get dry quickly in the air, when it rains they melt in water drops. After getting dry, the spores, which are similar to soft powder, are spread by air in the area. An entrance gate for the infection are wounds.   

Symptom

The symptoms are conidiospore penticles, which are formed in pycnids 1-2 mm wide under the bark.

Tree Species: Birch, Cherry, Apple Tree, Ash, Poplar

Part of a plant- attacked: Tree trunk

Pest significance: Harmful

Pest Category: Fungi

Invasive Species: No

Present in EU: Yes