It looks to me that the wound is the result of the large branch removal right in front of it, which is a very common response. The diameter of the wood had grown in conjunction with that branch and the cambium vascular structure heading to it was a high proportion of what was on the overall scaffold. You cut off the flow and the sap heats up and scorches the cambium (just my theory, there). The reality is that these wounds don't usually kill trees that are otherwise vigorous and the callous forming on the borders indicates this is the case here. The dead cambium was serving the removed branch anyway and now it's just a matter of the tree outgrowing rot to remain structurally strong. What don't kill you makes you stronger.

i dont believe in 'treating' trees to heal .. they take care of that themselves... the only treatment i would pay for is removal ... if ANY tree were that close to my house.. damaged or not ..... i wouldnt spend time on the computer asking about it ... get rid of it ASAP .. as noted above ... get at least 3 estimates from insured contractors ... if you have a fireplace... keep the sectioned wood .... ken

Dave, I think the problem is that you have little to no practical experience. I don't think for a minute that you are lying; I just think you are very unfamiliar with the topic. If you were out "getting your hands dirty" more often you'd surely have a much greater appreciation for the advancements made in horticulture over the last century. I haven't directly addressed the particular instance of your tree because (a) I am not familiar with all the facts of the case and (b) I highly doubt you had enough controls on your experiment for it to have any meaning at all. In any case, your one trial would in no way discount or lessen the impact of the many carefully conducted trials that demonstrated the complete worthlessness of the various tree goops, such as the one you mentioned. Probably the most disappointing thing about all this is that there are still people who fall victim to the snake oil salesmen because they are too lazy or too set in their ways to research the topic. One does have to be willing in order to learn. One has to learn in order not to be a duped.

Let it be, it will heal itself. Tar and other tree patches actually cause more harm than good.