Spotting micronutrient deficiencies in your crops

To produce the best yields and highest quality, your crops need all of the essential plant nutrients. Even if adequate amounts of the primary nutrients – nitrogen, phosphorous and potassium – are available, a shortage of one or more secondary or micronutrients could limit yields and reduce the quality of your crop.

We’ve compiled a summary of micronutrient deficiency symptoms to help you identify what nutrients your crops may be missing.


Visible boron deficiency symptoms in crops are not common. Boron is immobile in plants, so symptoms appear on new growth. Symptoms include poor fertilization and seed or fruit set, poor growth or death of terminal buds, shortened internodes, and leaves and stems may thicken and become brittle. Forages and canola may have reddish or bronze discoloration or yellow mottling.


Chloride deficiency in cereals sometimes manifests as “physiological leaf spot” and resembles tan spot. Visible symptoms may include wilting followed by chlorosis, bronzing of leaves, yield loss and greater disease incidence.


Copper is immobile in the plant and deficiencies are noticed on the new growth first. Seriously deficient cereal plants will turn light green with dried and twisted leaf tips similar to frost damage. Mild deficiencies may result in low test weight and higher levels of disease, especially blackening of the seed heads known as melanosis. Copper deficiency is known to contribute to higher incidence of ergot in cereals.


Symptoms are not common in most field crops but may occur in high pH/calcareous soils. Iron deficiency is exhibited as distinct interveinal chlorosis of the upper leaves. Veins remain green with light green, yellow, or even whitish interveinal tissue. Deficient plants are generally spindly and stunted.


Manganese deficiency is most common in soils with high pH or organic matter. As an immobile nutrient, symptoms appear first on new leaves. In cereals, the new leaves become chlorotic creating a striped leaf effect. Gray specks may occur in cereals. Broadleaf crops show some mottling or interveinal chlorosis similar to iron deficiency.


Zinc deficiency symptoms commonly appear as stunted plants with shortened internodes and small leaves. Severe symptoms can result in “rosetting” of terminal leaves. Other symptoms include interveinal chlorosis and/or mottling of leaves and delayed maturity. Deficiency is most common in high pH soils, soils with low Zn levels and soils with high phosphorus levels.

Consider Rainbow Plant Food as a key part of your best management practices to ensure your plants are receiving optimal micronutrients. Whether you broadcast or apply it in-row, every plant across the field will have the necessary nutrients available when it’s needed most.

For a printable guide on micronutrient deficiencies, click here.

For application recommendations, click here.

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