Hi, My knock out roses' have holes in their leaves. Please see attached photo. Please let me know how to care for my roses so that they don't have holes and what is causing the holes. Also, should I pick the flower when it is finished blooming and past its pretty stage? Thanks and enjoy your summer! Rose
This looks like damage from rose slugs (an insect, not a real slug), and a common problem on roses. Here is our webpage on rose slug control: http://extension.umd.edu/hgic/rose-slugs-shrubs
And here is some useful info on Knockout roses: http://extension.umd.edu/hgic/rose-rosenot-always-look-%E2%80%98knock-out%E2%80%99-landscape-roses
As for pruning off the spent roses, this is optional. Traditionally, this saves a from shrub from investing more energy creating a rose hip, and the shrub can put that energy into more flowers, leaves and roots. But, you do not need to do this. There are so many blooms on a Knockout, that's a good thing.