What’s this sap on my acorns?

Thanks to Keith Day for this great question about a sap-like substance oozing from acorns on his live oak tree! Butterflies, bees, and other insects are flocking to the sticky goo. It’s great for them, but is the tree okay?

Well, although I’ve seen many instances of trees oozing sap from the trunk and branches, I’ve never seen live oaks doing so only from the acorns.

One major reason for oozing sap is bacterial infections, which are not a good sign. If the oozing is limited to the acorns, the infection may be limited to that area, and if so, represents no long-term problem for the tree and requires no treatment.

These acorns will all fall from the tree soon, and then you should keep an eye out for any other areas of oozing sap. If you had in mind to do some pruning on your trees soon, be sure to hold off until the ideal time: deep in winter, when the trees aren’t actively growing and sap isn’t flowing. That would most likely be sometime in January, but watch the temperatures to be sure.

Note: pruning of live oaks should be avoided from February to July, especially if sap is evident on the trunk or branches!

Winter is not easy to predict these days, with most years much warmer than what we’ve traditionally considered “normal.” If you notice sap oozing from any other areas, you might have a bigger problem, and since bacterial infections are not curable, I would suggest having an arborist out for a visit to get an actual diagnosis and recommendations on how to proceed.