Sap "misting" from Douglas Fir trees

Asked October 23, 2018, 11:13 AM EDT

We have been finding drops (almost a mist) of sticky , thick fluid on our cars, roof and decks over the past few weeks. Our property has many large Douglas Fir trees on it and we suspect the trees are the source of the fluid. We have seen this sticky stuff in the past few years but ignored it thinking it was a natural phenomenon. This year there is so much more sticky goo we are afraid the trees might be diseased. Does the Extension have experts that could investigate and diagnose our problem?

Lane County Oregon

1 Response

It's very likely the unwanted shower of sticky goo is generated by sucking insects living in the tree. Whether or not the infestation may affect the tree's general health can only be determined with an on-site evaluations by knowledgeable people.

Consider inviting at least 3 certified Arborists to evaluate the tree and its environment, and ask what suggestions of a diagnosis and potential treatment, if any. (We suggest Certified Arborists because they must pass an exam and must also accumulate continued education training.)

You can locate Certified Arborists in our region by searching with your zip code at