Physiological Disorders

Major Nutrients

1. Nitrogen (N) Deficiency

Symptoms

N deficiency is typically caused by insufficient N in the soil. Nitrogen deficiency begins as a uniform light green discoloration / yellowing (uniform chlorosis) of the oldest leaves. Yellowing starts from tip to base of the lower leaves and will proceed up. As the deficiency progresses, younger leaves will also become discoloured. Older leaves are golden yellow colour. Growth virtually stops when N deficiency is severe and become shedding of leaves.

Diagnostic Techniques

Nitrogen deficiency is easily diagnosed by symptoms alone, although leaf nutrient analysis can also be helpful. Nitrogen deficiency can be confused with Fe or S deficiency, although the chlorosis in those deficiencies is typically most severe on the youngest leaves. The reverse is true for N deficiency.

Management

Foliar application of 2% urea thrice at fortnightly interval or soil application of 1-2 kg urea / tree or root feeding of 1% urea (1 g/litre of water) 200 ml twice a year.

Deficiency Symptoms

Uniform Chlorosis

Yellowing Starts from Tip to Base

Yellowing of Leaves

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2. Potassium (K) Deficiency

Symptoms

• Symptoms first appear on oldest leaves and later spread to young leaves.
• Translucent yellow or orange spots develop on leaflets (Yellowing of leaf margin).
• Older leaves are showing necrotic spotting as well curling of leaflet tips.
• Leaflets with necrotic areas along the margins which later wither
• The tree appears yellow and nicky, the trunk in slender with few short leaves.

Diagnostic Techniques

Visual symptoms alone may be sufficient for diagnosis of this disorder although leaf nutrient analysis may be helpful in distinguishing late stage K deficiency from manganese (Mn) deficiency. These two deficiencies can be extremely similar from a distance, but close examination should reveal characteristic spotting and marginal necrosis in K deficiency or necrotic streaking for Mn deficiency. Potassium deficiency symptoms are also more severe toward the leaf tip and are less so at the leaf base. The reverse is true for Mn deficiency.

Management

• Regular applications of K fertilizers will prevent K deficiency and treat palms already deficient. On sandy soils, or those having little cation exchange capacity, controlled-release K sources are much more effective than the easily leached water-soluble K sources.
• Application of resin coated K2SO4 @ 3 - 4 kg/tree, four times a year along with 2 kg MgSO4 / tree.
• Root feeding of 200ml of 1% KCL per tree thrice a year.

Deficiency Symptoms

Leaf Declaration and Extensive Necrosis of Leaflet Margins and Tips

Leaflets Tip Necrosis and Curling

Small Chlorotic and Necrotic New Leaves and Trunk Tapering

Translucent Yellow Orange Spotting

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3. Phosphorus Deficiency

Symptoms

• Purple coloration in leaves (In severe cases may leaves turn yellow before drying prematurely)
• Sluggish growth
• Leaves stay upright
• Premature leaf shedding

The growth, leaf size and leaf number reduced. The root growth is restricted if phosphorus deficiency is recorded. There are no clear visual symptoms of phosphorus deficiency other than stunting and decrease in yield.

Management
Foliar spray of DAP 2% twice at fortnightly interval or soil application of FYM 5kg/tree. Root feeding of 1% DAP 2 ml twice a year.

Deficiency Symptoms

Yellowing and drying of leaves

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4. Sulphur Deficiency

Symptoms

Typical symptoms are yellowish-green or yellowish-orange leaflets. Old leaves remain green. Leaves droop as the stem becomes weak. In older palms, leaf number and size are reduced. Sometimes an apron of dead fronds develops around the stem due to weakness of the rachis. Nuts may fall prematurely. Copra is rubbery and of poor market quality.

Management

Soil application of gypsum 2 - 5 kg/tree/year. Root feeding of 0.2% (2g/litre of water) gypsum.

Deficiency Symptoms

Apron of Dead Fronds Develops Around the Stem due to Weakness of the Rachis

Leaf Number and Size Reduced