Understanding the genetic, environmental and management factors that govern fruit tree growth, development and cropping is very complex because numerous factors play a role in determining annual tree behavior over multiple years. Up until recently it has been possible to simultaneously consider a only very limited number of factors when trying to understand or interpret tree growth or performance over time. With developments in functional-structural tree modeling, it is now possible to study multiple interactions among numerous genetic, environmental and management factors while simulating tree growth. Using L-PEACH, a functional-structural model of tree growth based on carbon partitioning, it is now possible to do virtual experiments and study outcomes resulting from varying any one or multiple parameters for individual or multiple simulated years, and to practically demonstrate the effects of: styles of pruning, timing and amount of fruit thinning, seasonal temperatures, irrigation schedules and rootstocks on tree growth, yield and fruit size.