Bacterial Wetwood (Slime Flux Disease)

Question: I live in New Jersey and I have an old white oak in my back yard. Recently I have noticed some sap "weeping" out of the trunk in two places near the base of the trunk. I contacted an old forestry professor of mine at Texas A&M University and he said it was most likely bacterial wet wood. I did some research on the web and the most common statement was to spray the wound with insecticide to prevent the insects from doing further damage. My questions for you are as follows:

• What type of insecticide should I spray?
• Can you recommend a particular brand?
• What can I do to stop the weeping?

Answer: Think about this! Your tree has an inside stem rot called slime flux that is caused by a bacterium. Why would you need an insecticide?

Your tree has a major bole rot and is trying its best to compartmentalize off the damage. The "weeping" may be a good thing because it is having a slow, natural draining effect on an organism that needs a dark, damp environment along with favorable culturing conditions at summer temperatures. One interesting thing is that the weeping liquid is fermented sap which is alchohol based and toxic to new wood.

Several USFS "books" say not to bore holes to drain the rotting wood as it will further spread the bacterium. There is some debate about this practice. Actually, nothing can stop further rot except the tree's ability to isolate the spot by growing good wood around the diseased portion (the late Dr. Alex Shigo's research).

Using an insecticide will not help prevent the rot going on inside. You do see secondary insects feeding on sap and the rotting remains but they do not affect the disease process. It is not thought they spread the infection. Don't waste your money spraying for insects.

Wetwood Photo - Randy Cyr/GREENTREE Technologies/Bugwood.org