What is Lilac Witches’ Broom? Lilac witches’ broom is a serious systemic disease of lilacs for which there is no cure. Infected lilacs typically gradually decline until they die. The characteristic symptom is the development of witches’ broom (tight clusters of short, thin branches that all stem from the same point). These witches’ brooms tend to form near the base of the lilac but they … Continue reading Lilac Witches’ Broom