When to spray fruit trees?

It depends on what you are spraying. There are different schedules for different parts of the country and whether you are going organic or semi-organic or whatever. Usually, there is an application of horticultural dormant oil ( winter rate) after a mid winter pruning and then subsequent sprayings of insecticide and fungicides at different stages of development, such as before the buds open, after the flowers have dropped and during fruit development.Check with your local state agricultural office for a full schedule and list of products.