The most reliable indicator of fruit and pecan tree fertility needs is chemical analysis of the foliage, commonly called leaf analysis. This service is available through the OSU County Extension centers throughout Oklahoma.
Leaf analysis may be used to diagnose or confirm a particular nutrient problem in an orchard after symptoms are present. More importantly, leaf analysis can determine nutrient shortages or excesses before symptoms develop and yield is reduced. Frequently, it reveals that certain fertilizers being used are not needed, resulting in a more economical fertilizer program.
Pecans, peaches, and apples are included in the OSU leaf analysis program. Each sample will be analyzed for 1) nitrogen, 2) phosphorus, 3) potassium, 4) calcium, 5) magnesium, 6) manganese, 7) iron, and 8) zinc. If the soil pH has not been determined within the past five years, a soil test may be useful. Otherwise, a soil sample will not be necessary unless indicated by the leaf analysis recommendation.
Taking Leaf Samples
Accuracy of diagnosis depends upon accuracy of sample collection. Each leaf sample should represent a condition rather than certain acreage. It may represent one tree or several acres. The trees selected for each sample should be representative of the acreage or condition and the condition should be uniform as to soil and management practices.
You must judge the uniformity of your own trees to determine the number of samples necessary for accurate recommendations.
Sampling Guides for Apple, Peach, and Pecan 1. Collect all leaf samples now.
2. Do not mix varieties or kinds of fruits into one sample. Native pecan trees of a uniform area may be sampled as one variety.
3. Before sampling, inspect selected trees for mechanical injury, mouse or gopher damage, winter injury, or wet feet. These factors could influence nutrient levels without showing the true nutritional condition of the tree or trees.
4. Apple and Peach — Collect 100 leaves for each sample.
5. Pecan — Collect 100 leaflets for each sample.
6. Collect leaves from shoots that are convenient from the ground and located on different sides of the trees. Do not collect leaves from suckers or water sprouts.
7. Do not collect more than two leaves from one shoot.
8. Select apple and peach leaves from the middle of current season’s terminal growth.
9. Select the middle pair of pecan leaflets located on a middle leaf of current season’s terminal growth.
10. Remove leaves with a downward or backward pull so that the leaf stem (petiole) remains attached to the leaf.
11. Avoid leaves that have insect, disease, or mechanical damage or leaves not representative of the sample.
12. Do not use galvanized containers, rubber gloves, rubber sponges, or allow leaves to contact rubber material to prevent contamination of the sample with various elements.
13. Before the leaves wilt, wash them to remove spray residue and dirt. This may be done by dipping the sample in clear tap water, not exceeding one minute.
14. After washing, spread the leaves out to air dry until they crumble. This will prevent molding. Do not expose the leaves to direct sun or allow them to heat in a bag while drying.
15. Place the dried leaves in the sample bag and submit them with a completed information sheet to the Extension Center. One information sheet should accompany each sample.
*Simple leaves are produced on apple and peach trees while the pecan leaves are compound. Each compound leaf consists of several leaflets. For simplification the term leaf is occasionally used to denote leaflet in the case of pecan.
If you would like more information on collecting leaf samples call the OSU Extensoin office at 405-527-2174 and request fact sheet HLA-6232 on fertilizing fruit trees.
