Sunday, January 27, 2013

Hackberry Witches' Broom


Looking up into a Hackberry Tree (Celtis occidentalis) you might notice a branch with an unusually dense cluster of twigs.  These are known as Witches' Brooms.    Their exact cause is unknown, perhaps some injury or stress to the tree.  Associated with the Witches' Broom formations are two organisms, an Eriophyid Mite, Eriophyes celtis and a Powdery Mildew, Podosphaera phytoptophila.

Enlarge picture for more detail
I think a post on Eriophyid Miites is in order some time in the near future.  They are both ubiquitous and virtually unknown to the casual observer. 



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