|Flat Apple caused by Cherry Rasp Leaf Virus|
Killing the virus in the tree is not possible without also killing the tree. This tree will eventually die so it might as well be removed.
Removing the tree and treating the soil is an option but costly and dangerous and is only logical for commercial orchardists using the skills of a licensed pesticide applicator familiar with soil fumigation or soil treatments for nematodes.
For those with only a few trees, the best recommendation is to remove the tree, avoid planting cherry or apple trees or raspberries in this site and purchase those fruits from local farm markets or the grocery store.