Tree paint, wound dressing: What's the controversy all about?

It is unclear when wound dressings first began to make their appearance. However, for many years, they were a staple of "proper tree care." No doubt, wound dressings (tree paint) would still be the standard practice, if one innovative researcher had not called the practice into question.

Alex Shigo, a USDA Forest Service Researcher, was one of the first people to make the study of trees into a science. To discover how trees respond to wounding, he embarked on a 30-year mission of exploration, performing 15,000 tree dissections in the process.

While engaged in tree research, he extensively studied the subject of wound dressings (tree paint). He concluded that wound dressings are not beneficial, and in many cases, are detrimental to the well-being of trees that have been pruned.

There are, however, a couple of exceptions to the rule of "never use tree paint dressings." In commercial fruit production, some studies have shown that certain wound dressings, while not helpful in the process of closing tree wounds, can inhibit the spread of fungal diseases from one tree to another. Another exception to the rule is in the case of oak trees. In areas where Oak Wilt Disease is prevalent, it is highly recommended to paint new tree wounds immediately after pruning, to avoid infection of the tree. After oak trees are pruned, there is a 3-4 day window in which the pruned tree may be infected with Oak Wilt Disease. In this case, tree wounds should be painted immediately, but care must be taken to use the least toxic paint available. Although there are "natural" wound dressings available, tree paint is generally based on an asphalt emulsion. Do you really want to pave your tree? Exercise caution when choosing what kind of wound dressing to apply. Regular black spray paint is actually much less harmful to a tree than commercially-available, tar-based solutions.