Testing fruit trees for nutrient deficiencies.

Well-nourished fruit trees are unlikely to invite pests and disease. The following video shares strategies we presented at the 2024 Annual Fruit Grower’s Workshop in Alcalde, NM. We are using these strategies to manage a 4 acre fruit orchard in Fort Sumner, NM.

Sorry, no audio. If you prefer text, an outline of the video follows.

Modified Testing for Nutrient Deficiencies Leaf vs Sap Analysis

Testing for Nutrient Deficiencies-Leaf vs. Sap Analysis

by Mary Lucero

End-O-Fite Enterprises LLC


This version is modified from the original, which

was presented at the 2024 Annual Fruit Grower’s Workshop

Alcalde, NM.

Minor modifications support compliance with various online presentation guidelines.



Why test?

Orchards maximize yields and fruit quality by applying the right fertilizer at the right time.

Benefits of properly managed fertility:

•Increase crop yields

•Improve resistance to pests, disease

•Improve resistance to heat, drought, and stress. Increase profits

If (and only if) fertilizer is applied in the right amount.


“Poison is in everything, and nothing is without poison. The dosage makes it either a poison or a remedy.” Paracelsus (1493-1541)
Dangers of too much fertilizer:

ʉۢFruit quality declines

•Pests and diseases proliferate

•Profits and yields decline

•Fertilizer runs off, contaminates streams

•Soil acidification

•Soil salinization

•Air pollution

•Profit margins decline

•Environmental regulations proliferate

Fertilizer costs are increasing. Applying too much hurts your profit margins.  

How do you decide…

How much fertilizer?

What kind of fertilizer?

When to apply fertilizer?

An NAPT member lab is recommended because it will be subjected to independent testing.

Testing labs will often provide fertilizer recommendations.

Reasons microbiologists question these recommendations:

Recommendations rarely take into account the amount of nitrogen and other elements that will be made available to your crop if microbes are effectively liberating, transporting, and cycling nutrients.

Classic plant nutrition science says a cover crop will rob nutrients from my trees.

Microbiology suggests that a diverse cover crop will feed the microbes that fix nitrogen, solubilize phosphorus, and protect my plants from stress, pests, and disease.

How does a grower know what to believe?

Plant testing can tell you what a plant needs at a point in time.

We have tried four kinds of plant tests:

Visual diagnostics (Pros: Low cost, instant results Cons: Many deficiencies have the same symptoms)

Refractometer (Brix) testing (Pros: Low cost, same day results Cons: only measures dissolved solids, so it won’t ID which nutrients are missing, light, leaf age, temperature, moisture, and other variables can influence readings, tree leaves are difficult to extract sap from for analysis. )

Tissue testing at commercial labs (Pros: Reliable report of what leaves contain. Cons: Since many elements are stored in the leaf, presence may not indicate metabolic availability. It can take a few weeks to get results. Few labs test the availability of all essential elements.)

Sap analysis (Pros: Reliable report of metabolically active nutrients. Cons: Time, labor, and price are highest of these methods. Lab won’t test availability of all essential elements.)

Comment: Of the methods we have tested, sap analysis provided the most precise and reliable results. Visual analysis continues to be our most recommended, first line of defense since it is the most rapid indicator that a problem is present.

Visual diagnostics key:

We found an excellent summary of visual cues to plant nutrition at earthjuice.com. Note that we have no affiliation to this company, nor do we have any experience with their marketed products.

How to treat deficiencies:
We find that foliar fertilizers containing a balance of macro-and micronutrients can correct most visible symptoms before you get results back from the lab.

Groups that supported this presentation

NMSU Cooperative Extension-hosted 2024 Annual Fruit Grower’s Workshop
NM Farm and Livestock Bureau provided financial support for the 2024 Annual Fruit Grower’s Workshop
NM Fruit growers – meeting participants and colleagues help us sound out ideas. We learn from one another.
Western SARE -The sample testing and live presentation at the 2024 Annual Fruit Grower’s Workshop were supported in part by Western SARE project FW22-399.

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