Q.Will Grub Worms Affect Rose Bush
Will grub worms affect a rose bush?

They certainly can become devastating to your rosebushes blooms if the are the grubs from Japanese Beetles. It is best to apply some control to get rid of them. I do not like to use insecticides unless I really have to, in the case of Japanese Beetles and their grubs control it is a must do.
Here are some links to articles on the grubs and damages the Japanese Beetles can do, along with a product to help control them:
https://www.gardeningknowhow.com/plant-problems/pests/lawn-grubs-how-to-get-rid-of-grub-worms.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/japanese-beetles-roses.htm
http://www.bayeradvanced.com/insects-pests/products/season-long-grub-control-plus-turf-revitalizer