Knock Out Roses Turning Pink: Sport or Stress?

Q: Three-year-old red Knock Out roses now blooming pink. Cause and fix?

Rose expert Ryan Tilley explains:

Possibility 1: Genetic sport—spontaneous DNA change in a cane. Can create new varieties (e.g., 'Touch of Class' sported to 'Classic Touch'). Hybrid roses may revert to a parent color. Usually affects single canes, not whole bushes.

Possibility 2: Weather stress—unusual winter/spring causes color shifts. Greenhouse roses forced early show odd colors due to low light.

Possibility 3: Cold damage to buds/canes yields weird blooms. Many strange blooms seen in Atlanta area recently.