Pear rust requires a 2nd host species, juniper, to complete its development. As the spores develop on the leaves of the pears, you'll notice the orange circles on the leaf. While the tree may be unsightly, it won't die due to rust. Leaves may fall off prematurely this season. There is no treatment that will remove the rust from this year's foliage. If there is a juniper tree within a 1/4 mi, you may see rust again. 

This doesn't need fungicide, but if you chose to use a fungicide, apply before bloom in Spring with 2 applications spread by 7 - 14 days. If using fungicide, always follow the instructions on the label and don't apply during bloom.