MISSOULA — Witches’ broom sounds like something for Halloween, but for trees, it is not part of a costume. The broom, a dense mass of branches, is the result of dwarf mistletoe, a parasitic plant impacting Montana forests.

“A lot of times infected trees look really green and healthy, but it's actually just the mistletoe, the parasitic plant,” said Amy Gannon, who runs the Forest Pest Management Program for the Montana Department of Natural Resources & Conservation (DNRC).

Every species of Montana conifer, except Ponderosa pine, has been targeted by its own specific mistletoe. The infection starts small, then grows for years, or even decades, slowly choking the tree beneath it.

“They have to have a living host and they draw the nutrients from the host tree,” Gannon said. “That's robbing

See Full Page