The easiest would be a controlled release complete fertilizer or high nitrogen organic. But any other nitrogen source applied once a week would get things on track. If you go with a high salt fertilizer like 21-0-0, ammonium sulfate, It's safer to dissolve it before application at a rate of about one teaspoon per gallon. The highly soluable Miracle Grow products will green things up rapidly.

Your tree could be a little short on nitrogen. But nectarine do naturally drop some healthy looking leaves. That would be the oldest leaves as is occurring on your tree. So I don't think this is serious.

I do think the tree definitely shows signs of having a problem. There are two symptoms that causes concern. It is correct that a healthy tree will normally drop older leaves about the time of a major blooming, or a major growth flush. However, normal leaf drop is only the older yellow aged leaves. The leaves that have dropped from this tree are quite green and are still healthy. A second, and greater CONCERN is, as far as I can assertain from the pictures, is that the leaves have not fallen in the normal abscission process. Normally the abscission of a leaf takes place where the petiole (stem) is attached to the branch. When a leaf falls because of normal abscission the entire leaf with the stem STILL attached to the leaf blade falls as a complete unit. "But under certain types of STRESS, separation occurs at the junction between the petiole and the leaf blade" (fm. Biology of Citrus) leaving the stem still attached to the branch and only the leaf blade falls. With out actually seeing the tree in person it is very difficult to be certain what is going on. As you live in California, it is possible that the tree can have some sort of a leaf disease, as I see two leaves with a browish cast. If it were my tree I would flush the soil with at least an amount of water equal to four times the volume of the container. Actually, the leaves do not show all that many symptoms of damage due to a high soluble salt content. Usually there is much more leaf burn and especially leaf TIP BURN when soluble salt symptoms show up. However, a good flush certainly will never hurt and can give a definite possibility of doing a lot of good. Keep an eye on the tree after you flush the container, if it is a leaf blight or leaf diease of some sort it should show up better in the next week or so. However, I think the problem is with the soil. You also might take the temperature of the soil and tell us what it is. Let us know how the tree does. Take care - Millet

Hi, I have a washington orange tree(dwarf)about 4 feet tall in my backyard and i noticed that half of the branches were dying. It was healthy for a year and all of the sudden this things happened started 2 months ago. Most of the leaves turns yellow and small branches turns to brown. New fruits about 10 mm in size were falling. I watered my tree almost every other day. Applied citrus fertilizer and still not working. How could i keep my tree healthy? Thank you so much.