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Site Specific Nutrient Disorders |
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Zinc Deficiency |
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Areas affected |
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Zinc deficiency symptoms are commonly seen both in acid as well as alkaline
soils where cassava is cultivated in India. |
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Deficiency symptoms
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Interveinal chlorosis of younger leaves is the characteristic symptom of zinc
deficiency. First, small white or pale yellow spots or patches appear in between
the veins of leaves. The lobes of leaves become narrow, chlorotic and will curl
upward. In case of severe zinc deficiency, tips of leaves become necrotic. |
Zinc deficiency symptom on cassava leaf |
Zinc deficient plant in acid soils |
Zinc deficient plants in alkaline soils |
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Corrective measures
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Apply 12.5 kg Zn / ha as ZnSO47H2O at planting or incorporate ZnO before
planting (cassava). If the problem is found to be less severe, foliar
application of 1-2% solution of ZnSO47H2O is very effective. Under alkaline
conditions of Salem and Gujarat, for cassava, stake treatment is recommended
since Zn supplied to soil is precipitated at high pH (6.7-8.0). Under such
situations, dip the stakes of cassava in 2-4% solution of ZnSO47H2O for 15
minutes prior to planting or apply 1-2% solution of ZnSO47H2O as foliar spray. |
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Boron deficiency
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Areas affected
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Boron deficiency is seen in some acid soils where cassava is cultivated in
India.
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Deficiency symptoms
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Since boron is highly immobile within the phloem, the symptoms of boron
deficiency appear on growing tips of cassava. If plants are uprooted, we can see
very poor lateral root development and death of root tips. The plants will
become shorter by a reduction in intermodal length. At the growing tip of
plants, leaves will be small and deformed with short petioles and gummy lesions
on the petioles. Brown gummy lesions on the petioles at the leaf tip and on
growing portion of stems is a symptom of boron deficiency.
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Boron deficiency symptoms on cassava leaf
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Boron deficiency symptoms on cassava stem
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Corrective measures
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In areas where boron deficiency seen, apply 10 kg / ha B as borax or dip the
stakes in 0.5-1 % borax solution before planting cassava. |
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Magnesium Deficiency
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Areas affected
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Magnesium deficiency is found both in acid soils (Kerala, Andhra Pradesh) and
alkaline soils (Tamil Nadu, Gujarat) where cassava is cultivated in India.
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Deficiency symptoms
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The lower leaves of magnesium deficient plants show interveinal chlorosis. At
first the tips and margins of these lower leaves develop chorotic symptoms.
Later on the symptoms spread inward covering the entire portion of the area in
between the veins. In areas where severe magnesium deficiency is seen, the
leaves become necrotic and develop whitish colour. Magnesium deficiency symptoms
are common in soils where there is excessive amount of potassium.
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Magnesium deficiency symptom on cassava leaf
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Magnesium deficient plant
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Corrective measures
In areas where magnesium deficiency is found, apply 20-50 kg Mg / ha as MgO,
dolomite or MgSO4. If MgO and dolomite are used, broadcast and incorporate
before planting since they are relatively insoluble. If MgSO4 is used, apply it
as band application near plants shortly after planting since it is soluble. |
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Manganese deficiency
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Areas affected
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In alkaline soils of Tamil Nadu and Maharashtra, manganese deficiency commonly
seen. Manganese deficiency is common in calcareous soils.
Deficiency symptoms
The typical symptoms of manganese deficiency are interveinal chlorosis of leaves
in the middle portion of the cassava plant. Manganese deficiency symptoms will
not be seen on youngest leaves and by which we can distinguish manganese
deficiency from iron deficiency. In case of severe manganese deficiency, the
leaves will become completely chlorotic. |
Manganese deficiency symptoms on cassava leaf
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Manganese deficient plant
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Corrective measures
In manganese deficient areas, soil application of MnO or manganese sulphate or
foliar spray of MnSO44H2O (1-2% solution) is recommended. Dip the stakes in 5%
solution of MnSO4 4H2O for 15 min. before planting. |
Iron deficiency
Areas affected
Iron deficiency is widespread in alkaline soils of Tamil Nadu and Maharashtra
where cassava is grown.
Deficiency symptoms
Iron deficiency is characterized by chlorosis of younger leaves. First, the
symptoms will appear in interveinal areas of leaves and later on all portions of
leaves including veins will become chlorotic. In the case of iron deficiency,
the green veins will become prominent in between the yellowish interveinal
areas, while in the case of manganese deficiency, the boundary between green
veins and chlorotic interveinal areas becomes diffuse. Iron deficient plants
become stunted in growth, leaves will be smaller in size than normal leaves but
will not be deformed.
Iron deficiency symptoms on cassava leaf |
Iron deficient plant in Vertisols of Tamil Nadu |
Iron deficient plant in Vertisols of Maharashtra
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Corrective measures
Apply 1-2% FeSO4.7H2O solution as foliar spray. Dip stakes of cassava in 5%
FeSO47H2O solution for 15 minutes before planting. |
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