The Q&A Archives: Oak Losing Sap

Question: My 10 year old oak is losing sap from the trunk. The sap seems to spew out of the bark from a small hole. I haven't seen any evidence of a pest. Seems like the sap is escaping due to pressure. So far I have mixed a simple solution of dishwashing liquid and water and sprayed the spot to keep it open and clean. I then used a product called 'Triple Action' that is an insecticide and a fungicide in one. Can you help me ? I don't want to lose this tree. The tree isn't showing any sign of distress yet, no wilt or lost leaves.

Answer: Your tree has a condition known as "bacterial flux" or "slime flux". It results when a wound or crack in the bark allows bacteria and other microbes to infect the sap. Their activity causes a fermentation of the sap resulting in the "bleeding" you see which is most commonly either frothy white or brownish colored. You will often notice an odor to the sap which can attract wasps and some species of butterflies...sort of a "bug beer joint" you might say.

Spraying will not alleviate the problem. Some authorities recommend drilling a shallow hole to release pressure which can build up and separate bark from the interior wood, thereby aggravating the damage. Others disagree, indicating this only further wounds the tree.

Most trees, if healthy and vigorous will "wall off" the infection and heal over within a season. Old or weak trees often lack the vigor to effectively do so. Either way, the problem seldom is a threat to the tree, just a nuisance to the owner. Once summer arrives the sap flow should go away.

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