Native to the United States and the official tree of the state of Texas, the pecan is a large tree — up to 150 feet — and long-lived, as some in Texas are more than 150 years old. Their longevity is a testament to how little care these trees require. Pecan trees thrive and even fruit without interference from people. For high-quality pecans, however, the tree requires fertilizer and especially zinc, a micronutrient. Zinc is crucial to the development of pecan nuts.
Symptoms of Zinc Deficiency
When a pecan tree suffers from a zinc deficiency, its new leaves fail to grow beyond a certain point. They curl, and the veins discolor. Some branches may die or lose all the leaves except for those at the tip. The significance of a zinc deficiency is most evident in what may happen to the nuts. Pecan nuts may be hollow or not as full as they should be.
Apply a zinc foliar spray when the pecan tree is flush with new yellow-green leaves in the spring. Spray the tree either in the early morning or evening to avoid burning the leaves when the direct sun hits them. Reapply the zinc every two weeks until June 1. Pesticides may be mixed with the zinc if necessary. Follow the manufacturer's label instructions about how to combine the two, and wear protective goggles and clothing.
The type of sprayer you use depends on how many pecan trees you have and how big they are. To apply the zinc to a small tree, a hose-end sprayer is sufficient. If you have just a few trees, a pump sprayer or tank sprayer works well. Growers with larger orchards will find it more efficient to use a mechanical sprayer. If the sprayer doesn't have enough pressure to reach the top of the pecan tree, use a ladder. Thorough coverage of all parts of the tree is crucial. Zinc sulfate comes in both powder and liquid forms, and may be purchased at nurseries and gardening centers. Pecan tree experts at Texas Pecan recommend the powdered form because it stores better.
Although pecan trees need little care, they are unable to absorb zinc from the soil. For this reason, soil applications aren't recommended. Annual foliar feedings of zinc help keep the tree's foliage healthy and make it a better producer. Read the entire label before mixing and applying the zinc sulfate. Spray the entire tree so it is saturated with the zinc solution and it runs off the tree. Make sure to hit the top of the canopy.