Birch Besom

Taphrina betulina

Birch Besom, also known as Witch's Broom, is a deformity caused by the fungus Taphrina betulina affecting Silver Birch trees. It results in a dense growth of shoots from a single point, creating a structure that resembles a witch's broom or a bird's nest. This gall can occur at any time of the year, but it is more noticeable in winter when the trees are leafless.