Q. My young fruit tree suddenly lost its leaves. This happened after I changed to the fall watering schedule. A couple of weeks ago I had tree service fertilize all my trees and shrubs including fruit trees.  They said there is nothing in their mixture that could have caused this. A. Trees and shrubs are normally fertilized in early spring, not in the fall. There is nothing wrong with fall fertilization but it should never be done in the fall to plants that are sensitive to freezing temperatures.             When fertilizing in the fall, it is best to wait until all growth has stopped with only a few weeks remaining before the leaves change color. The month of November is usually a good time to do this.             There are typically two reasons for sudden leaf drop if temperatures are still warm; soils are overly dry or improper fertilizer application. I agree with your tree company. There is nothing in their fertilizer mix that would cause leaves to drop BUT if fertilizer is applied incorrectly, or the soil is dry when it is applied, then the tree might experience unexpected rapid leaf drop. Desert Dawn nectarine leaf drop after drought             If the soil dries out too much, leaf drop should be gradual in the fall. Leaves wilt, they turn gray because they are drying out and they fall from the tree in about a week’ s time. If fertilizer is applied too close to the tree’s trunk or applied when the soil is dry, leaf drop would be sudden; “overnight”. Always fertilize when soils are wet and at least 2 to 3 feet from the trunk.             Regardless, I don’t believe the tree has any long-term damage. To be sure, bend small branches from where the leaves dropped. They should bend easily without breaking. Supple branches after unexpected leaf drop in late summer or early fall is a good indicator. This means they will most likely come back.             The worst time for unexpected leaf drop is in the spring during periods of active growth. Leaf buds for the following year have not yet been initiated. In the fall, when the tree has stopped growing but already formed leaf buds for next year, it would grow new leaves in a couple of weeks if temperatures are warm and the soil moist. What to do?             Irrigate the soil above the tree roots with a hose, flooding the areas where fertilizer was applied. Apply 15 to 20 gallons of water slowly to these areas. Do it again in one week. New leaves will emerge in 10 days to two weeks. Enough leaf buds will remain unopened for next spring’s growth.