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Micronutrient Deficiency Symptoms and Correction Measures in Coconut

Micronutrients are essential for plant growth and play an important role in balanced crop nutrition, though plants don’t require as much of them. Lack of any micronutrients in the soil can limit the plant growth and shows deficiency symptoms, in coconut some of micronutrient deficiency symptoms and its correction measures.

Boron deficiency

B deficiency on coconut palm is manifested as sharply bent leaflet tips, commonly called “hook leaf”. Leaves have a serrated zigzag appearance. Young and newly developing leaves become deformed called as little leaf. One of the most common symptoms of B deficiency is the failure of newly emerging spear leaves to open normally. They may be tightly fused throughout their entire length, or the fusion can be restricted to basal or distal parts of the spear leaf. In a chronic stage, multiple unopened spear leaves may be visible at the apex of the canopy.

Correction measures: Soil application of borax 0.2 to 0.5 kg /tree/year or foliar spray of borax 0.2%. Spraying is commonly practiced when coconut palms are at the nursery stage at a rate of l to 1.5 grams per seedling.

Manganese deficiency

The newest leaves of Mn deficient palms emerge chlorotic with longitudinal necrotic streaks. As the deficiency progresses, newly emerging leaflets appear necrotic and withered on all but basal portions of the leaflets. This withering results in a curling of the leaflets about the rachis giving the leaf a frizzled appearance (‘frizzle top’). On new leaves of Mn-deficient palm, necrotic leaflet tips fall off and the leaf has a signed appearance. In severely Mn- deficient palms, growth stops and newly emerging leaves consist solely of necrotic petiole stubs.

Correction measure: Soil application of MnSO4 @ 10 Kg/acre

Magnesium deficiency

Magnesium deficiency appears on the oldest leaves of palms as broad chlorotic (yellow) bands along the margins with the central portion of the leaves remaining distinctly green. In severe cases leaflet tips may become necrotic. Older leaves become bronzed and dry appearance. Leaflets show necrosis and turn to reddish brown with translucent spots yellowing starts at the tip and spreads to the base.

Correction measure: Soil application of MgSO4 1-2 Kg/tree/year. Root feeding of 200 ml of 0.2% MgSOtwice a year

Sulphur deficiency

Typical symptoms are yellowish-green or yellowish-orange leaflets. 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.

Correction measure: Soil application of gypsum 2 - 5 kg/tree/year. Root feeding of 0.2% gypsum

Zinc deficiency

Little leaf symptoms, rosette appearance, necrotic patches in interveinal areas, delayed fruiting.

Zinc deficiency is characterized by formation of small leaves wherein the leaf size is reduced to 50%. Leaflets become chlorotic, narrow and reduced in length. In acute deficiency, flowering is delayed. Zinc deficiency will also lead to button shedding.

Correction measure: Soil application of ZnSO4 @ 10 Kg/acre

Iron deficiency

Interveinal chlorosis in terminal leaves; older leaves remain green, necrotic spots in chlorotic region. Iron deficiency usually appears on palms growing in poorly aerated soils or those that have been planted too deeply. Water logged soils and deep planting effectively suffocate the roots and reduce their effectiveness in taking up nutrients such as Fe. The main symptom of iron deficiency is chlorosis or yellowing between the veins of new leaves (Uniform chlorotic new leaves as the deficiency progresses, the tips become necrotic and leaf size reduced.

Correction measure: Application of FeSO4 0.25 to 0.5 Kg/tree/year

Calcium deficiency

Young leaves exhibit narrow white bands at margins, interveinal chlorosis, rusty appearance in leaf margin, rolling up of leaves and occurs only in acid soil

Correction measure: Soil application of lime based on lime requirement and root feeding of 1% calcium nitrate.

Copper deficiency

Coppery bluish leaf, rolling of terminal leaves due to loss of turgor, leaves appear to be bleached grey and fail to produce flowers.

Correction measure: Soil application of CuSO4 @ 10 Kg/acre.


Writer :: A. Anjaneyulu*      Published on :: 11-May-2019

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