irrigate mature trees

The roots of established fruit trees are typically in the top 2 to 3 feet of soil, and these trees prefer deeper, less frequent watering than a vegetable garden or turf grass.  The frequency and quantity of watering will depend on soil type and on weather conditions.  For more specifics on orchard tree irrigation, see the series of Orchard Irrigation fact sheets available from USU Extension (http://extension.usu.edu/files/publications/publication/Horticulture_Fruit_2008-01pr.pdf).