Question
Hello,

I live in south Louisiana. I have many oaks in my property. They have swollen areas on the bark that splits and makes a round center. I can send you a couple of photos if you would like to see what I am talking about. Can you tell me what this might be?

Thanks,
Linda  

Answer
Sounds like one of the canker type diseases.   The term "canker" is used to describe a killed area in the bark on the branch or trunk of an infected tree. More than 20 species of fungi that cause canker diseases are found in North Dakota. These fungi commonly invade wounded or injured bark tissues to form a canker and subsequently produce reproductive structures called fruiting bodies. Spores from these fruiting bodies serve as inoculum for new infections. Cankers may be "superficial," forming on the outer portion of the bark and doing little damage, or "cambial" when extended into the cambium, where the bark sloughs off and sapwood is exposed allowing subsequent decay to develop in woody stem tissues.

Perennial cankers are most conspicuous and destructive. There are two types. In target cankers (Figure 14) a succession of callus tissue repeatedly forms on canker margins over a period of years. Diffuse cankers are generally oval in shape and either sunken or swollen, little or no callus is formed, and stems, twigs and branches are girdled.

Infections of living trees by canker fungi are influenced by site, age, tree vigor, environmental conditions and cultural practices. Stress by drought, lack of fertility, insect defoliation, or herbicide damage predisposes trees to canker. In general, cankers are more prevalent on young trees, on suppressed low vigor trees, or on trees at poor sites. Cankers most often occur on trees predisposed to infection by environmental stresses such as herbicide drift, defoliation by insects or chemicals or root damage.

Here is a web link to a fact sheet on cankers that will give good information.
http://plantclinic.cornell.edu/FactSheets/cankertree/cankertree.htm

If after looking at the fact sheet you still are not sure this is what you are seeing you can send me the pictures and I will try to ID it further. [email protected]