Shumard Oak disease

Asked May 3, 2013, 3:47 PM EDT

I planted several Shumnard Oaks last spring. By mid summer several of them had sooty black areas on their trunks and oozed a bubbling sap like substance. I treated them with Aliette Fungicide. It seemed to stop the progression, leaving an opening in the bark. They were planted in full sun, normal moisure and soil, with no mechanical damage at planting. No observed pests. see attached photos. No other damaged noted to twigs or leaves. Do you have an idea of the agent at work here and the prognosis?

Fort Bend County Texas

1 Response

Since you don't see any obvious signs of insects, you are most likely dealing with a fungus or bacterial infection. Damage may have occurred at the commercial nursery during their handling of the trees by the trunks. Also, if the condition occurs on the southwest side of the trunk the damage may be sun-scald.

The ooze is commonly call "slime flux." (You can google "slime flux" for more discussion.) The cell sap becomes infected with the fungal or bacterial organism, and the organism ferments the sugary cell sap. The result is a sour smelling leakage that will attract insects, and eventually these insects (primary wood borers) will cause more problems for the tree than you have now. Keep spraying. I would recommend Consans Triple Action 20 which is a bacteriacide, fungicide, and algaecide all rolled into one. Also, I would apply an any ornamental insecticide as needed, particularly after a rain.

In the spring, as the sap rises from the roots to the growing points, slime flux is more prevalent. Generally, despite the cause - the condition becomes less and less during the summer, and then goes away.

If you suspect sun-scald, you may want to "white-wash" the trunks of your trees. A white wash can be make using the cheapest interior white paint you can find mixed with equal parts water.