Q.Double Knock-Out Roses root problem
Double knock-out roses are dying faster than we can replant, tiny white “seed pearls” attached to what’s left of disintegrated roots – what can I do to soil before planting new bushes? (Neighbor says pour gasoline in holes b4 filling with mixture of Black Kow and garden soil and new plant.)

Some fertilizers, like Osmocote, will form little pearl looking things on the roots because that is how the bushes get the nourishment. So that may not be it. I would contact a local Consulting Rosarian in your area and have them come take a look. You can look some up at the American Rose society website. That is the route I would go. I definitely would not do the gasoline thing! I would amend the soils with a good compost prior to replanting though.