It was suggested that I use Vitamin b1 for my fig tree. The fig tree is probably close to twenty five years old or more. It looks sad right now. I know they require a lot of sun, but there are two huge mesquite canopies covering it. I've thinned out the canopy somewhat. But you can only do so much. The guy who thinned out the branches a little says he uses Vitamin B1 for his fig tree and iron. Will this help a tree that is this old?