When the tip of a branch on certain trees and shrubs gets damaged, it may remove apical dominance. This results in a tuft of small twigs and branches from the buds that had previously been under control by the top bud on the stem. The dense proliferation of twigs resembles a witche's broom, thus the name.

Witche's brooms may be caused by a number of factors. Some insects will infest and kill the apical bud on certain species trees and shrubs. There are a few diseases that may also result in this type of growth. In some cases, the cause is not known.

The twigs that develop on a witche's broom are usually poorly attached to the branch and may break off in the wind or ice storms. Even so, they are generally not a serious problem for the plant. They just look bad in the dormant season.

Witche's brooms that form on evergreen trees are often the source of some interesting new specimens for the landscape. People will cut off the broom and graft it to a rootstock of the same species. This will form a unique, dwarf standard plant that has different foliage from the mother tree and usually stays in a dwarf form.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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