Q.Cedar Apple Rust on a Flowering Crabapple

I hope you can help me. I have a pink flowering crabapple that I planted this past spring and it has recently developed cedar apple rust. I am currently treating it by spraying it with a fungicide. I can’t remove the source of infection as it must be from a neighbor. My question is – is there some type of a preventative or treatment that I can apply at the root level? If the tree gets much bigger, I am not going to be able to spray the highest leaves as I am not going to be able to reach them. Please help!!