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10 nutritional disorders of pepper

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10 nutritional disorders of pepper

  1. 1. Pepper Production Guide for Asia and The Pacific 89 11. Nutritional Disorders of Pepper airly extensive work has been done in Malaysia on nutritional disorders in pepper, including deficiencies of Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Iron, Manganese and Boron. The problems resulting from cultivation of pepper in acid soil conditions have also been examined. A summary of these studies follows. 11.1 Nitrogen Deficiency Nitrogen Deficiency symptoms are generally characterised by poor growth, with pale and yellowish leaves (Fig. 59). At first, the lower leaves turn yellowish but the upper canopy of affected plants tends to remain relatively green. In severe cases, leaves of the entire plant show a characteristic yellow to orange-yellow discolouration and the extreme end of the leaf tip becomes necrotic in some instances. Leaf abscission is common in severely affected plants. Fig. 59. Nitrogen Deficiency Symptoms, (a) and (b). (a) (b) Continued F
  2. 2. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 90 Fig. 59. (Continued) (c) Leaves in upper canopy remain green while lower leaves are chlorotic (d) Leaves are chlorotic with yellow to orange yellow colouration Nitrogen deficiency may be overcome by applying 40, 80 and 160 g N per plant in the first, second and third year respectively, if pepper is planted in clayey soils on gentle slopes. On coarse-textured soils and steep slopes, the rate should be increased by as much as 50%. If urea is used to supplement complete fertilisers, it must be buried in shallow trenches. 11.2. Phosphorus Deficiency Clear symptoms of Phosphorus deficiency often rare in the field. In severe cases, the most striking symptom is stunted growth of the plants. This effect is not so much reduced terminal growth, but more of restricted lateral growth due to poor secondary branching. Leaf blades of mature leaves become very dull looking, turn bronze coloured, tend to be stiff and show necrosis at the tips in some instances, before abscission occurs (Fig. 60).
  3. 3. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 91 Application of 35g, 70g and 140g of P205 fertilizer per plant in the first, second and third year respectively is recommended for plantations on shale derived soils of clay to clay loam texture. About 30% of the P205 should be in water-soluble form during the immature stage of growth. Rock phosphate is less efficient than water-soluble phosphate and higher rates may be required if the former is used. In sandy soils, phosphate application in the third and subsequent years should be half that of the recommendation for residual shale soils. Application of phosphate as a foliar nutrient is possible and spraying triple superphosphate 1.0–2.0 % is recommended in this regard, but this is more expensive. 11.3. Potassium Deficiency Potassium deficiency symptoms can be seen on the distal end of affected mature leaf blades becoming necrotic, brittle and grey in colour. Necrosis is usually confined to the distal end, while the portion beyond the boundary separating necrotic and live tissues displays a ‘V’ shape band, which is yellow to reddish brown. This band sometimes occurs without the ‘tip burn’ symptom (Fig.61). Fig.61 Potassium deficiency symptoms: (a) Necrotic tips or ‘tip burn’ (b) ‘V’ band of yellow colour separating necrotic tips and live tissues Fig. 60. Phosphorus Deficiency Symptom: Leaves are dull looking, bronzy in colour and tend to be stiff.
  4. 4. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 92 Application of 40g, 80g and 160–200 g K2O fertilizer per plant in the first, second and third year respectively is adequate for optimum performance on residual shale soils. For coarse sandy soils, the rate should be increased to 270g K2O per plant from the third year onwards. 11.4 Magnesium Deficiency Magnesium deficiency symptoms first appear on older leaves and progress to younger leaves. In the early stage, chlorosis occurs in between main veins. This usually starts from the central proximal half of the leaf. The chlorotic area enlarges to the leaf tip and subsequently towards the leaf margin. A light dramatic leaf fall is often induced, leaving the branches quite bare with only younger unaffected leaves remaining on the plant (Fig.62). The area near the petiole often stays green and gives an arrowhead effect of green tissue penetrating the yellowing areas on the leaf. Fig. 62 Magnesium deficiency symptoms: (a) and (b) Dramatic leaf fall in severe case leaving bare branches and (c) Chlorosis in between main veins of leaves (a) (b) (c) Apply 1.0 kg dolomite at planting and 0.5 kg per plant in subsequent years or every alternate year. For acute deficiency, 200 g kieserite per plant may be applied to correct the disorder.
  5. 5. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 93 11.5 Calcium Deficiency Visually, Calcium deficiency is first observed in fresh mature leaves as yellowing or chlorosis which starts on either or both edges near to the petiole end or middle part of the leaf blades. The marginal chlorosis advances inward, followed by necrosis. The proximal and distal ends of the affected leaves are either green or pale green. Tiny pinhead necrotic spots may appear scattered between the main veins on the lower and upper surfaces of the leaves. Leaf abscission occurs before the central portion of the leaf becomes necrotic. Die-back may occur at the growing point. Leaves of the lower canopy are usually more severely affected than those of upper canopy (Fig.63). Fig.63 Calcium Deficiency symptoms: (a) Early stage of Calcium Deficiency (b) Advanced stage-necrosis at the edges of leaves Application of 1.0 kg dolomite per plant at planting and 0.5 kg in subsequent years can correct the deficiency. Deficient plants may take 2 – 3 months for complete recovery after applying dolomite. For acute deficiency, foliar spray using 1.0% solution of calcium nitrate or 0.4% of anhydrous calcium chloride has been recommended as for other crops, but is expensive and is not a long-term solution. 11.6 Iron Deficiency Iron deficiency begins in the younger branches and is characterised by interveinal chlorosis. The chlorosis occurs in between the main veins and smaller veins as well, forming a fine reticulate pattern of green veins contrasting sharply with a pale green or yellow background. The youngest leaves may be completely green or even white. In acute deficiency, the internodal length of terminal shoots and lateral branches is markedly shortened and leaves tend to crowd together at the upper end of the canopy. The berries of affected vines appear pale green to yellow (Fig. 64, (a) and (b))
  6. 6. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 94 Fig.64 Iron Deficiency symptoms: (a) Symptoms are more severe on upper canopy of affected vines, (b) Healthy and iron deficient leaves and berries. When acute Iron Deficiency occurs, treatment is more difficult than for any other nutrient deficiencies. Fortunately, treatment is often not necessary as the plants normally recover as they grow older, probably due to the development of more extensive root systems, which enables a greater uptake of iron. Treatment is attempted only in severe cases. Foliar application of FeSO4 salt at 0.5% concentration is useful but several applications may be necessary to provide effective control. NB: Iron Deficiency may often be induced by natural occurrence of excessive amounts of Calcium in the soil or from over liming a soil with excessive amounts of lime or dolomite. 11.7. Manganese Deficiency Manganese deficiency symptoms are more severe in the upper canopy of affected plants. Younger leaves turn chlorotic or yellowish white with only the main veins remaining green. The older leaves produce a characteristic herringbone pattern with green veins and the areas between the veins turn yellowish white. At a later stage, small necrotic spots appear and grow in size in the pale areas. Manganese and iron deficiencies can occur simultaneously as both are induced by over liming. While the symptoms of young leaves in a manganese-deficient plant can easily be confused with those of iron, the two deficiency symptoms are distinctly different in the mature leaves. When deficiencies are prolonged and severe, berries also show characteristic symptoms (Fig.65).
  7. 7. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 95 Fig.65. Manganese Deficiency symptoms a) b) c) d) Foliar sprays and soil applications of manganese sulphate have been used to correct manganese deficiency. However, the former have generally been more successful than the latter. One or more foliar sprays of 0.5% manganese sulphate can usually correct the deficiency. 11.8. Boron Deficiency Boron deficient plants are stunted with shortened internodes and reduced branching. Young and recently mature leaves show characteristic symptoms of interveinal chlorosis at the distal and central portion. Young leaves are small and distorted with pronounced puckering and necrotic lesions on the main veins (Fig.66).
  8. 8. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 96 Fig. 66 Boron deficiency symptoms: (a) Young leaves are small and distorted with pronounced puckering and necrotic lesions on small veins, (b) Stunted growth with shortened internodes and reduced branching, interveinal chlorosis at distal and central portion of leaves Soil application of 10 g of sodium tetraborate per plant has been found to be highly effective in correcting the deficiency and to increase leaf boron concentrations to adequate levels. 11.9. ‘Acid Soil’ Conditions Necrotic spots develop along the main veins and also between the main veins in the middle portion of the affected leaves. More than half of the distal portion of mature leaves may become chlorotic. Symptoms in recently mature leaves are more severe than those of the younger and older leaves. In immature pepper, growth is severely retarded. The root system of affected plants develops poorly, having black and decayed roots, which are brittle. Leaves are shed prematurely and the yield of affected vines is poor. These symptoms are similar to those that have been described as ‘Aluminium’ toxicity and multiple deficiencies (Fig.67). Application of 0.5 – 1.0 kg dolomite per plant together with a foliar spray of trace elements can usually correct the disorder. Recovery is often slow, taking two or more months. Application of water soluble kieserite (200 g/plant) in combination with dolomite has been found to hasten recovery. The disorder may be complicated by nematode damage to the root system, particularly on sandy soils.
  9. 9. 11. Nutritional Disorders of Pepper Pepper Production Guide for Asia and The Pacific 97 Fig.67 ‘Symptoms of Acid’ Soil Condition: (a) and (b) Necrotic spots along the main veins, and (c) Plant affected by ‘Acid Soil’ a) b) c) 11.10. Manganese Toxicity Young leaves are normal while older leaves are affected. Dark brown to black spots appear first at the leaf margin before extending towards the central portion of the lamina. This eventually leads to a striking interveinal pigmentation. Premature shedding of leaves and poor secondary branching are observed in cases of acute toxicity (Fig.68). Fig. 68 Manganese Toxicity symptoms: (a) Characteristic interveinal pigmentation mainly on mature and older leaves in affected plants, (b) Leaves showing increasing severity of Manganese Toxicity from left to right Application of 1.0 kg dolomite per plant, improving drainage of the planting site, re-mounding with fresh soil and use of fertilisers with minimum manganese content should overcome Manganese toxicity.

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