Tuesday, 12 August 2008

Taphrina betulina - Witches Broom

[photo by James Lindsey@Wikimedia Commons]

Genus: Taphrina
Family: Taphrinaceae
Order: Taphrinales

Birch Witches' Brooms are masses of densely branched small twigs that resemble a witch's broom stuck in the tree's canopy. Witches' Brooms can be induced by various parasites including Taphrina betulina Rostrup. (Current thinking believes gall inducing phytoplasma may be responsible for some witches' brooms.)

Witches' Broom on Wikipedia

Birch Leaf Curl is induced by a Taphrina betulae (Fckl.) Johans. infection.

It has been found that Taphrina betulina infections in White Birch (Betula pubescens) trees cause reduced growth (by an average of 25%) and vigour, and 'Witches' Broom' growths (pictured here), the number and sizes of which correlate to the DBH (diameter at breast height), but not to the reductions in height and vigour [1].

1. (from Abstract) The effects of Taphrina betulina infection on growth of Betula pubescens, Y. A. Simmons and S. Woodward, European Journal of Forest Pathology, 2007 - Vol 24, Issue 5, p.277-286

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