Hi Bill:

Thanks for reaching out to Ask Extension. I am happy to help!

Thank you for sending along pictures. This is definitely a case of "brooming" on Douglas-fir, which can be caused by Douglas-fir dwarf mistletoe. 

However, this appears to be a physiological broom or genetic broom, that usually occurs singly in a given tree. No plants (mistletoe), fruiting structures (fungi), feeding patterns, or other biotic indicators are associated with this type of brooming.

Great find!

Thank you,

Thanks for your response.

That's correct, Bill. Not always, but usually if mistletoe is that high up in the canopy, then there will be more plants in the lower branches and surrounding trees. This is because female flowers shoot seeds, coated in a sticky layer, up to 55 feet away! Seeds can also stick to birds or other wildlife and be carried to trees much farther away.

I did reach out to the Director of the College of Forestry Research & Demonstration Forests for input. They are familiar with the tree and suspect the witches broom may be caused by a rust (fungus), but it's too high to sample.

Fun facts: Dwarf mistletoe is a hemiparasitic plant that lives its entire life within the canopy of a tree. Mistletoes possess chlorophyll and typically carry out photosynthesis and are partially parasitic on the roots or shoots of a plant host. Female flowers shoot seeds, coated in a sticky layer, up to 55 feet away. Seeds can also stick to birds or other wildlife and be carried to trees much farther away.

Thank you!