There is actually a parallel technique nearing the finish line that does sort of this. The gene they moved though is from wheat not another tree species, but still seems to give great blight resistance. Currently the barrier to it is entirely regularity. I believe it would be one of the first plants approved to just be released into the wild without something to prevent it reproducing naturally. The normal anti genetic engineering types are very opposed, but it seems likely it will get approved in the next few years.
What authority can enforce approval or disapproval to release something into the wild? Suppose I own land next to a national park. Then can’t I plant whatever I want on that land, trusting that it will spread into the park?
There are two parallel efforts going on at present for restoring the American chestnut, a backcross effort and a GMO-based approach. This sub-thread is concerned with the GMO strategy.
A buddy of mine has been involved in this project for years at SUNY ESF, and it's very exciting how successful it has been. There are dozens of test sites around central New York that have healthy (albeit very young) populations of American Chestnuts.
https://www.nytimes.com/2020/04/30/magazine/american-chestnu...