eXtension

Douglas Fir sap stream - insects needing treatment or normal?

Asked May 6, 2019, 1:33 PM EDT

We have several large Douglas Fir trees in our backyard. One of the largest has developed a few sap streams (see photos). In reading online, there are various opinions expressed about how "normal" such streams are and whether they should be left alone or treated. One page mentioned a moth that usually does only minor damage, but also a beetle that is more dangerous to the tree. I don't see any other streams on the trees we have. Thanks in advance for any guidance or advice. We'd hate to lose this tree because it's over 100ft tall and a centerpiece within the landscape.

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Washington County Oregon forestry urban forestry

2 Responses

Hello and thank you for the photos.

Pitch streaming can be caused by a number of different factors, and often difficult to pinpoint the reason. This does NOT look like the characteristic pitch "blobs" caused by the sequoia pitch moth that you referenced. They could be due to the Douglas-fir beetle, which is probably the beetle that you mentioned. However, if that is the case then the pitch is actually a good sign, especially if there are only a few streams. This means that the tree is successfully defending itself against the beetles. If instead you saw dozens of streams on the tree, OR, no pitch but collections of reddish sawdust-like material in the bark crevices, this would be more of a concern.

Other things that can cause pitch streams include woodpeckers (sapsuckers), wind damage, or wounding. Often, it's not a sign of anything wrong.

Hope this helps.

Thank you. That is helpful information. That first photo shows the full extent of the sap, so there are not any other streams. It's all below 5' above the ground; we do see woodpeckers drop by, but generally higher up. There has been no limb-fall in that area. I have not seen any sort of friable material on the tree or on the ground below the sap streams. So, I hope this is just a minor issue that the tree can clear up by itself. We'll keep an eye on it using that photo to see if it gets any larger with time.