Oak – ‘Sudden Oak Death’

Q: I read in the newspaper a few weeks ago about a “Godzilla” fungus that is attacking oak trees. My husband and I were taking a walk recently and we noticed that our neighbor has some type of black lesion on his water oak trees. Is there any way to protect our trees from this disease?

A: Sudden oak death (SOD) was the disease you read about. One of its symptoms is indeed oozing cankers on oak trees. However, since there is no evidence that SOD has infected trees in Georgia, my bet is that you have a much more common malady of oaks: slime flux.

This bacterial infection of the trunk beneath the cambium layer causes sap to ferment, leading to oozing goo on the bark. You will sometimes discover it by smell: the odor resembles vinegar. Other times you might find the foaming ooze by the large number of insects attracted to the sweet liquid.

In any case you can’t do much about it other than helping the tree fight its own fight internally. Water the tree during summer heat. A good rule of thumb is two gallons of water for every inch of trunk diameter (measured at 4.5 feet above the ground) for each day between individual waterings. Apply mulch under the entire branch spread of the tree to keep the soil cool and uncompacted.

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