Kockout roses dying
I have had a spectacular row of Knockout roses at the front of my garden - about 30 of them. In their third year a couple died, and in their 4th year (last year) another nine died. They did not seem to have any disease (fungus or bacteria) but might have had a virus. The leaves showed no sign of disease, nor the roots. There are now gaps in the row - the remaining 20 or so roses look very healthy.
Should I in-fill with young roses? I have five mature Knockouts that I could use to fill gaps, should I use them?