I found this witches broom-like growth on my pink p-willow and was wondering what caused it. There are several on this tree, but not on the black, fantail and curly trees. The pics were taken Jan 12, '13. Thanks for any help. I'm not sure of the name of this willow, only know the florists name of pink. It is very early, fully open but not showing any yellow. Catkins are smaller than others I have.
Herman
Some witch's brooms are caused by pathogens, others by genetic defects, others by environmental factors. Impossible to say for any particular broom without detailed analysis.
Resin
