Q: I have a mature Valencia orange tree that has yellowing leaves and dead end tip branches. It also has some dried yellow fruit. The tree is watered three times a week for 45 minutes each time with three bubbler type irrigation system heads at the tree drip line. Any thoughts on what may be the problem?
A:ย Although yellowing leaves can also indicate a lack of nitrogen, the dead end branches and your current irrigation schedule tells me the tree needs more water. If you are fertilizing three times per year as recommended in late winter, spring, and fall, the other important input is water. While your placement of bubblers is appropriate, the scheduled watering is not ideal. Citrus trees do best with deeper watering on a less frequent basis. During the summer, every 7 to 10 days to a depth of 36 inches is recommended. In the spring and fall you can back that off to every 10 to 14 days and in the winter to every 14 to 21 days.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions and photos may be emailed to tucsongardensage@gmail.com.
