I forgot to say that the spirea is wilting and some branches are dry and crispy. I'm only assuming that the gophers are killing it but there aren't any pests on it. Could I be correct with my assumption about the gopher or is there a disease that these are susceptible to?

Are you sure it doesn't just need water? Gophers don't typically eat roots, but if they're burrowing around, they could expose roots that may be drying out.

At first I thought it was a mole and I read that moles eat grubs and other insects and gophers eat plants so I'm blaming it on gophers. I have had seedling trees pulled under ground and couldn't believe gophers would do that but then I read that it is one of their tricks. The bed is mulched and watered regularly so I don't think it's a lack of water.

Gophers DO eat roots, Moles eat worms and grubs and burrow around plants and shrubs.