The idea is to keep the center free of thin, twiggy growth. This way you'll boost blooms and reduce the chance of disease. Nothing to fear here. Any day above freezing, spray your fruit trees and other deciduous trees with dormant oil spray. If pesticides and their possible toxic side effects in your garden concern you, have no fear.
Dormant oil is a mechanical killer.
It smothers pests and their eggs while they're sleeping out the winter in the tree bark. Recycle plastic knives. I hope you've saved your old plastic picnic knives. They make sturdy, durable row markers for seeds or even as identification tags in the perennial bed. Otherwise, cut strips from old white food containers.