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Tree Sap Identification

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From: Steve Colburn
Eureka, IL
How can I test a substance to see if it is or is not sap from a spruce tree? A waxy/oily material has appeared on a newly installed and painted drywall surface at church. Either it came in through an open window from a nearby tree on a hot day or maybe it derives from the new building material itself.

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From: Jay Hayek
Extension Specialist, Forestry
Department of Natural Resources and Environmental Sciences
Greetings Steve:

Probably the most economical way to tell if this "substance" is indeed tree sap is to simply determine if it has a sticky texture; though, this is certainly not a fool-proof test. If it is not sticky, you'll likely have to examine the building materials more closely.

Although I would have to research tree sap volitalization more thoroughly, the majority of "sap" spray (i.e., honeydew) is actually from insects (aphids and scales). This is a common complaint among vehicle owners who park adjacent to or beneath the crown radius of a tree.

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