From what I've read, it seems like in this case you want to try and stimulate the pine tree to grow faster than it usually does. You can do this by using a fast acting fertilizer that can stimulate excessive growth, something that has both iron and a good amount of nitrogen. I have heard that recycled beer or even urine have a good amount of nitrogen and can be used to boost up slow -releasing fertilizers. In this case, you will also want to provide your pine tree with more water than usual. Good luck and I hope your tree gets better.