Fruit Tree Leaf Analysis

The last 2 weeks of July is the time to take leaf samples from your fruit trees. Foliar sampling is generally the most reliable tool for assessing the nutrient status of orchards. It gives you an idea of actual nutrient uptake and can reveal deficiencies that might not have any other symptoms. It's not too late to correct deficiencies for many nutrients in fruit trees with foliar sprays. Leaf sampling also gives you the luxury of confidently doing nothing if all is well.

If nutrient levels in an orchard are known to be stable and fertility management practices are unchanged, sampling every two to three years is sufficient. However, if there are known deficiencies or nutrient management practices are changed, sampling should be done every year until foliar nutrient levels are stable and any deficiencies are corrected.

The samples are taken from shoulder-height, mid-shoot leaves of this year's growth that are fully mature as shown.

Avoid damaged, abnormal and spur leaves as well as those that are not fully expanded. Approximately 10 leaves from all sides of a tree can be taken from 10 trees to give a total sample of 100 leaves. If your orchard is variable you can break it up into logical management units to sample separately if practical. Otherwise, you could take fewer leaves from more trees to get your 100 leaves. Different varieties have different critical nutrient levels and should be sampled separately. Try to avoid collecting leaves from trees at the outer edges of the orchard. Put the leaves into a labelled paper bag to keep them clean and bring them to an accredited lab. Standard analysis includes N, P, K, Ca, and Mg, and costs less than $20 per sample. If micronutrient excesses or deficiencies are suspected, these can also be analysed at an extra cost. A list of labs with prices can be found on the OMAFRA website.

One of the more common nutrition problems found in Ontario orchards is nitrogen level, excesses being more common than deficiencies. Another common one is K excesses or deficiencies. Excess K can lead to Mg deficiency. Zinc, Manganese, and Boron deficiencies are found in isolated cases. Any of these problems can be found by leaf analysis, and most can be corrected in-season with foliar sprays. The cost of analysis is offset many times over by savings in fertilizer costs or increases in yield and/or quality.

Related Links

• Leaf & Petiole Tissue Analysis Program

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