Thank you for your question. This certainly is concerning, and I would love to give you a quick answer. This can be caused by insects, but it can also be the result of a bacterial infection called slime flux. Without being able to see whether there are indications of boring by insects, this is difficult to diagnose. I suggest that you take some photos closeup to the tree trunk, looking for holes (which may have been created by insects or a bird), and collect some of the white exudate, and visit the Clackamas County Extension office between nine and noon, and one and four o'clock, any business day. There should be Master Gardeners there who can assess what is going on. I hope this is helpful. Good luck!