Apply Fertilizer Once or Multiple Times to Fruit Trees?

Picture of tree sent by reader. He thought this might be a nitrogen deficiency or nutrient of some sort. But look at how green all the other growth is and how much it is growing. Its healthy but there is a problem with one shoot.

Q. I see many times where you've said fruit trees only need feeding in the spring.  However, without periodic applications of nitrogen my three-year-old peach tree leaves become yellow.  Could there something going on I should investigate?

A.  Yellowing can be from lots of different things, not just fertilizer. If enough fertilizer is applied in the Spring, you should get dark green leaves and lots of new growth. Enough for the whole year. You want lots of new growth in the spring and the fertilizer to slowly disappear from the soil. This should take about two months.

This plum tree has severe iron chlorosis. It affects the entire tree. This was corrected with three foliar sprays of iron a few days apart. It became dark green again.

            There is one reason why you might apply fertilizer frequently to plants. Extremely sandy soils. This soil would be like planting in a sand dune. I haven’t seen any of it in Las Vegas, but I have in Bullhead City, Arizona. When the tree is planted in extremely sandy soils, fertilizer is applied lightly every couple of weeks and water daily, sometimes twice a day.

This is iron chlorosis in ornamental or purple leaf plum. Notice all the leaves are not yellow because of all of the purple pigments in the leaves. It shows itself as chlorotic because it turns from a dark purple to a lighter pink. I am guessing the reason it became chlorotic is because of over watering the lawn and root rot beginning in the deeper rooted plum tree.

            Running out of fertilizer in a couple of months from a spring application gives the tree time to set up fruit production for the next year. Fertilizing the tree continuously pushes lots of new growth but may cause low fruit production. The tree sets up its fruit production for the next year any time from about late June through September. It depends on the fruit tree.

This is borer damage to peach in July. The weather is hot and so the branch where the borers are located was cut off from its water supply and turned brown. If this happened during the cooler months or in a cool climate, you might see some yellowing occurring on this branch first.

            The tree should grow about 18 inches each year when they are young and established. No more than that. Excessive growth is frequently caused by over applying fertilizers. Too much growth and it’s just is wasted since it is cut back during winter pruning. After fertilizer is applied in early spring, the tree will grow dark green leaves for the first two months and then the leaves will become a lighter shade of green as the season advances, but they shouldn’t be yellow.

Peach tree yellowing in a lawn probably because it's receiving too much water and the deeper roots are suffocating. I like it that they have cleaned the lawn grasses away from the trunk. This helps to minimize damage from line trimmers and mowers. But it would be nice if that grass were removed to about 2 feet away from the trunk rather than only 10 inches.

            If yellowing is caused from a lack of nitrogen fertilizer, the older leaves become yellow, not new leaves at the ends of branches. If yellowing is caused by a lack of a micronutrient fertilizer such as iron, yellowing appears in leaves at the ends of branches. The yellow leaves in both cases becomes worse as the season progresses unless the correct fertilizer is applied to correct it.

Leaves are still yellow and showing interventional chlorosis (leaf blade is lighter color than the veins) which means the leaves don't have enough iron in them to cause them to green up. The only way to cure this is to spray it with an iron solution multiple times a couple of days apart until the leaves become a darker green. You stop spring when the leaves have gotten the deep green color you want. Kerex was applied to this tree earlier and it still remained chlorotic.

            Yellowing leaves can be from watering too often or poor soil drainage or both. This leaf yellowing also appears at the ends of branches, like iron. Yellowing can be from planting too deeply. The tree should be planted the same depth it was in the container or grown at the nursery.

Here several trees are showing a lighter green color than the surrounding trees. I could spray the leaves of these trees multiple times with an iron solution until the greened up or I could apply an iron fertilizer to the soil just before new growth begins in the spring. A single application of an iron fertilizer in early spring is enough usually for the entire year. Leaf sprays have to be applied multiple times on fruit trees to get them to green up.

            Yellowing can because by early borer damage. Borers damage the trunk or limbs by their feeding which interrupts the flow of fertilizers, like iron, to the leaves. Because the leaves lack iron, they turn yellow.

            Investigate all these possible situations before jumping to the conclusion it’s lack of fertilizer. If you’ve applied your spring application of fertilizer and the leaves are dark green, it’s not a fertilizer problem.