Pine witches' broom (Candidatus Phytoplasma pini-related 16SrXXI-B) is a phytoplasm of pine trees. It is a native of North America.
Symptoms of this disease include needle yellowing and twisting, as well as profuse, clumped growth called "witches broom". This disease is native to North America, although information regarding its effect on tree growth is sparse.
For more information about this plant pest, see the CABI data sheet.