Wandering through Witches' Brooms

Towering Tree at Sunset - Near Fish Creek - July 2024

​Three decades ago exploring the trails at the top of Steamboat Boulevard was a solitary adventure. The Sanctuary was not a thing, and the boulevard ended just after the bridge over Fish Creek. I loved my runs up to that bridge, looking at Fish Creek flowing below. It was where I went the day I learned that my Great Aunt Dorie had passed. When I was a kid and we’d just arrived to visit family in Glen Burnie, Maryland, the grown-ups would stand around gabbing forever. Aunt Dorie would whisper, “would you like to go to the stream?” And we’d head to the little bridge over Sawmill Creek, skipping stones and discussing important matters like snakes and black cherry soda. 

These days I still meander the trails around Fish Creek. There’s a lot more folks around, and I pass by many houses to get there, but the sound of the water rushes through my head, the ferns bordering the trail gently graze my legs, and the scent of lush undergrowth and earthy pine fill my nostrils. The best way to wrap up the day.

The other evening something caught my attention. A beam of the sunset lit up a large round cluster on one of the spruce branches - like the tree was offering up a giant bowl of golden grapes. Looking closer I was bemused by the mounded cluster of green and orange needles. Kind of like the tree, but not. I then noticed quite a few trees in the entire area were similarly adorned. 

These clusters are known as Witches’ Brooms, so-named long ago because it was thought the affected trees were a place for the witch to rest and conveniently park the vehicle (broom) as well. We now know that the brooms are a symptom of the fungus Chrysomyxa arctostaphyli, causing Spruce broom rust. Melampsorella caryo-phyllacearum causes Fir broom rust. To be honest I can’t tell the difference between spruce and fir and I am not a needle-roller. Apparently spruce needles are square and roll easily between your fingers, and fir needles are flat and do not roll. Hm. 

The fungus can cause weakness in the tree, and eventually death. And the fungus, in order to get going at all, needs an alternate host, which in this area is the bearberry. The spores develop on the bearberry and then are blown by the wind to infect the trees. Large, mature trees are sometimes more susceptible as there is more area to target, and infections are influenced by microclimatic conditions and the distribution and abundance of hosts, according to this US Forest Service article. 

The article offers up management suggestions: remove affected trees, remove dead trees. My favorite suggestion is to “maintain as many live trees as possible.”  

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