Fir trees dripping pitch or sap onto deck. - Ask Extension
We have lived in our house over 30 years and never had this problem to this extent. It is ruining our deck and making it unusable as your feelt stick...
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Fir trees dripping pitch or sap onto deck. #351971
Asked August 10, 2016, 3:33 PM EDT
We have lived in our house over 30 years and never had this problem to this extent. It is ruining our deck and making it unusable as your feelt stick to the deck.
There seems to be a lot of pinecones up high in the tree. Could they be dropping this sap? Not all of the deck is even under trees so the wind must be blowing it.
Is this a sign of disease?
Clackamas County Oregon
Expert Response
Sap flow from the trunk of your trees could be a sign of disease, however, to determine possible causes and implications for tree health, we need more information. What species of fir tree? Where is the sap originating from (trunk, branches, cut ends of branches, etc.).
It could help to send some photographs showing the setting, the tree, parts of the tree where sap originates. Please send directly via email if possible.
It could help to send some photographs showing the setting, the tree, parts of the tree where sap originates. Please send directly via email if possible.
I believe these trees are douglas firs. The sap looks like it is running down the trunks but my husband says it is also coming off the pinecones which are hanging up very high since we had lower branches trimmed. We thought that would help but the upper branches are doing the same thing. The trees were dripping sap long before we had branches cut off which was just a couple weeks ago. The parts of our deck getting the drippings aren't even under the tree so it must be blowing in the wind over to the deck. I never thought this was something that could happen but it is. Any advice would be welcome. Thank you. Lori
Yes, they do appear to be Douglas-fir. Sap flow from Douglas-fir of this size is rather common and there are various reasons it happens, many we know about and some that remain a mystery.
Sap or pitch flow is often associated with pruning wounds - both old and new. It appears that your trees have been pruned in the past as well as most recently. Some of the pitch on your trees seems associated with old pruning wounds. Pitch moths colonize pruning wounds when pruning is done in spring or summer and the result is chronic pitch flow associated with pitch moth infestation at branch wounds, year after year long after pruning was done. To avoid this, prune in fall and winter, not in spring and summer.
Also, green cones often exude pitch, which becomes particularly noticeable in years with abundant cone crops - this year is a BIG year for Douglas-fir cones and I suspect that much of the sap on your deck is dripping off of cones and showing up as more of a light shower rather than a stream.
Sap flow from the trunk can also be caused by wood rot fungi - root rot fungi when it is near the base, and stem rot fungi further up the trunk. This can be a more serious problem over the long term as it affects overall tree health and also the risk of tree failure (breakage) due to rotten wood. I do not see obvious signs of this in the photos, but if you see significant sap flow from the trunk that is not associated with branches, a hazard tree evaluation by an arborist may be called for.
Bark beetle attacks also cause sap flow, usually many small streams from many individual beetle attacks. Healthy trees can "pitch out" a small number of bark beetles and not be seriously affected. Trees stressed by drought or other issues can attract beetle attacks and be overcome by large numbers of beetles. Healthy trees are not normally damaged by bark beetles, but they can be overcome by concentrated attack of many many beetles if lots of down wood is left on the ground to breed excessive numbers of bark beetles nearby. I did not see signs of this in your photos, but it is something you could watch for.
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Sap or pitch flow is often associated with pruning wounds - both old and new. It appears that your trees have been pruned in the past as well as most recently. Some of the pitch on your trees seems associated with old pruning wounds. Pitch moths colonize pruning wounds when pruning is done in spring or summer and the result is chronic pitch flow associated with pitch moth infestation at branch wounds, year after year long after pruning was done. To avoid this, prune in fall and winter, not in spring and summer.
Also, green cones often exude pitch, which becomes particularly noticeable in years with abundant cone crops - this year is a BIG year for Douglas-fir cones and I suspect that much of the sap on your deck is dripping off of cones and showing up as more of a light shower rather than a stream.
Sap flow from the trunk can also be caused by wood rot fungi - root rot fungi when it is near the base, and stem rot fungi further up the trunk. This can be a more serious problem over the long term as it affects overall tree health and also the risk of tree failure (breakage) due to rotten wood. I do not see obvious signs of this in the photos, but if you see significant sap flow from the trunk that is not associated with branches, a hazard tree evaluation by an arborist may be called for.
Bark beetle attacks also cause sap flow, usually many small streams from many individual beetle attacks. Healthy trees can "pitch out" a small number of bark beetles and not be seriously affected. Trees stressed by drought or other issues can attract beetle attacks and be overcome by large numbers of beetles. Healthy trees are not normally damaged by bark beetles, but they can be overcome by concentrated attack of many many beetles if lots of down wood is left on the ground to breed excessive numbers of bark beetles nearby. I did not see signs of this in your photos, but it is something you could watch for.
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Thank you so much for your response. It is most helpful.
Lori Thrasher
