Nutrient Deficiencies & Disease Management in Crops

Nitrogen (N)

Deficiency Symptoms:

Yellowing of older leaves, stunted growth.

Disease Associations: Deficiency increases Fusarium and Verticillium wilts; excess N increases powdery mildew.

Management Solutions:

Apply balanced N; prefer nitrate-N; avoid excess ammonium forms

Phosphorus (P)

Deficiency Symptoms:

Purpling of leaves, poor root development

Disease Associations: Promotes susceptibility to Pythium, Phytophthora

Management Solutions:

Apply P based on soil test; avoid deficiency

Calcium (Ca)

Deficiency Symptoms:

Blossom end rot, poor cell walls

Disease Associations:

Deficiency linked to Pythium, Sclerotinia, bacterial soft rots

Management Solutions:

Use lime, gypsum, or foliar Ca; ensure consistent watering

Magnesium (Mg)

Deficiency Symptoms:

Interveinal chlorosis in older leaves

Disease Associations:

May increase risk of Phytophthora

Management Solutions:

Apply Mg sulfate or dolomitic lime

Potassium (K)

Deficiency Symptoms:

Leaf edge browning, weak stems

Disease Associations:

Enhances resistance to Alternaria, Botrytis, Erwinia

Management Solutions:

Use potassium sulfate/silicate to strengthen tissues

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Sulfur (S)

Deficiency Symptoms:

Yellowing of young leaves, stunted growth

Disease Associations:

Reduces synthesis of plant defense compounds

Management Solutions:

Apply elemental sulfur or sulfate fertilizers

Cupper (Cu)

Deficiency Symptoms:

Leaf deformation, dieback, weak growth

Disease Associations:

Promotes Sclerotinia, Erwinia when deficient

Management Solutions:

Apply Cu fertilizers or Cu-based fungicides

Manganese (Mn)

Deficiency Symptoms:

Interveinal chlorosis, especially in high pH soils

Disease Associations:

Decreases resistance to Take-all, Rhizoctonia

Management Solutions:

Use Mn sulfate or chelated Mn; avoid over-liming

Zinc (Zn)

Deficiency Symptoms:

Small distorted leaves, short internodes

Disease Associations:

Deficiency reduces resistance to viruses and fungi

Management Solutions:

Apply zinc sulfate or chelates

Iron (Fe)

Deficiency Symptoms:

Yellowing of young leaves in high pH soils

Disease Associations:

Indirectly affects plant vigor, disease resistance

Management Solutions:

Apply Fe chelates (EDDHA) or foliar Fe sprays

Boron (B)

Deficiency Symptoms:

Poor fruit set, death of growing tips

Disease Associations:

Deficiency weakens resistance to Fusarium, Pythium

Management Solutions:

Apply borax or boric acid carefully (avoid toxicity)

Silicon (Si)

Deficiency Symptoms:

Abnormal flowering, reduced seed, could harden leaves

Disease Associations:

Decreases resistance to powdery mildew, blast

Management Solutions:

Use potassium/calcium silicate; beneficial in cereals & cucurbits