Re-Planting Fruit Trees.
If you have a project to remove and re-plant some fruit trees in your garden. You should be Ok as the soil will not normally carry any build up of pests and disease that will effect the new plants.
Remove as much of the old root system as you can and dig in plenty of organic matter before replanting.For Most fruit trees spent mushroom compost is ideal for this purpose,the exception to this is blueberries which is more of a bush than a tree but needs slightly acidic conditions.