Diagnosing Nutrient Problems 

in Orchards

Tools:
Visual diagnosis
Leaf sampling
Leaf test result interpretation
Soil sampling
Soil interpretation

The following is a summary of chapter 17, "Diagnosing Sick Orchards", by Dr. R. Stebbins in Tree Fruit Nutrition- shortcourse proceedings, edited by A. Brooke Peterson and Robert G. Stevens

First and foremost, recognize that there are many causes for certain "symptoms" seen in the orchard.  Lack of vigor, chlorotic or pale leaves, small leaves, and many other symptoms may have numerous causes.  Many orchard problems have their origin underground and can easily be overlooked.

Secondly, recognize bias. People with different experiences and technical training may diagnosis the same problem very differently.

Recognizing symptoms:

• Know what to look for and when
  Symptoms of deficiencies of iron, boron, and zinc tend to appear at or even before bloom.
  Symptoms of potassium or magnesium deficiency may not appear until August.

• Questions to ask yourself

  1. Is there a pattern to the symptoms? Are all the trees affected  or just some throughout the orchard?

  2. Could the chlorosis be caused by herbicide application?

  3. Does the chlorosis show up first on young leaves or older leaves (relates back to remobilization of nutrients within plant)?

  4. Is my irrigation set optimal or am I over/under irrigation?

  5. Are the affected trees in a certain location where soil type is different (ex. on a slope where erosion may lead to shallow soils with less organic matter then trees at the bottom of a slope)?

  6. History questions:

     • How was the land previously used?

     • What was the soil pH before planting?

     • Was fertilizer added to planting hole?

     • Were pre-emergence herbicides used?

     • Was the land leveled before planting?

  7. Established plantings:

     • How quickly did the problem occur?

     • What fertilizers, herbicides and pesticides have been used?

Diagnostic tools

Visual diagnosis-
because Ca, B, Cu, Fe, Mn, and Zn are rather immobile in plants, deficiency symptoms will most likely occur on new growth first.  In contrast, the more mobile N, P, K, and Mg symptoms will appear on older plant parts. This can be helpful in quickly ruling out certain elements. However visual diagnosis should be verified with soil and leaf analyses before corrective actions are taken.

• This is because:

• symptoms may be caused by a deficiency of more than one nutrient;

• deficiency of one nutrient may be caused by an excess of another;

• other factors such as insect, disease, and weather injuries can create symptoms similar to nutrient deficiencies;

Taking leaf samples prior to visual symptomolgy is useful because:

• by the time a nutrient deficiency can be accurately diagnosed, it may be too late to correct the problem or the damage may be beyond the point where nutrient additions can profitably correct the problem.

Other tools:
Leaf sampling

Leaf test result interpretation

Soil sampling

Soil interpretation

Updated November 24, 2004

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