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Diseases

Disease Diagnoses

  • If leaves dry rapidly and fruits show brownish dry-rot eventually destroying the whole crop, the disease could be late blight
  • If seedling stem cankers and dark brown spots form on the leaves causing possible defoliation that expose fruits to sun scald, The disease could be early blight
  • If leaves have tiny brown black angular leaf spots with possible defoliation the disease is possibly Septoria leaf-spot streaks on stem and fruits show attack severity.
  • If leaflets of the lower leaves wilt and curl and dried whole leaves curls upwards, turn brown wither but remain attached to the stem. If the stem split open and the pith is often discoloured.  Or if young fruits show discolouration of vascular system, they show deformation and stunting on mature fruits birds eye spots are visible the disease is possibly Bacterial Canker.
  • If there is yellowing and wilting of the lower leaves with slight dropping at high temperatures. If the vascular vessels also appear brown, which is restricted to the stem near the soil level, while roots show a severe browning and decay. The disease is possibly Fusarium Wilt.
  • If irregular dark green spots appear on the foliage which eventually dries or blossoms drop. Or initially a small spot appears on the fruit which eventually enlarges. The disease is possibly Bacteria spot.
  • If you see a rapid wilting of plants, large number of adventitious roots that are produced on the stem. The pith showing brown discolouration the disease is possibly bacterial wilt

Scroll further down to read more on symptoms and control of the specific disease

Blossom End-rot

Symptoms

  • An early sign of the disorder are a water soaked spot near the blossom end of the fruit.
  • This turns brown and enlarges to cover almost half of the fruit.

Possible causes

  • Too fast growth during the early stages followed by sudden drought especially when the fruits are small.
  • Excessive nitrogen and infrequent watering.
  • Calcium deficiency especially in young fruits.
  • Low application of nitrogen to calcium deficiency soils

Control

  • Application of CAN
  • Apply calcium chloride foliar feed at 15kg/1000 liters (Higher concentration will damage leaves).
  • Lime calcium deficient soils.

Late Blight

Symptoms

  • Occurs under cool and high humidity conditions especially wet season.
  • It is characterized by rapid drying of leaves and brownish dry rot of fruits often destroying the whole crop.

Control

  • Spray with recommended curative fungicides.

Early Blight

Symptoms

  • It occurs during hot weather.  It causes stem cankers on seedlings and small irregular dark brown spots on the leaves.  As they enlarge they show a concentric pattern.  The result is partial defoliation of the crop.
  • It causes premature fruit drop and low quality fruits.
  • It is soil borne and the fungus usually survives on plant debris.

Control

  • Field sanitation.
  • Crop rotation.
  • Spray with recommended curative fungicides.

Septoria leaf spot

Symptoms

  • Disease occurs at all stages of the plant.
  • It attacks the solanaceae family and survives on plant debris.
  • Its development is favoured by wet weather.
  • It is characterized by the presence of tiny brown black angular leaf spots on leaves.  The spots can cause defoliation, which then exposes fruits to sun scald.  In severe attacks, lesions appear on stems and fruit stalks.

Control

  • Spray with recommended curative fungicides.
  • Keep field free from weeds.
  • Remove and burn infected debris.
  • Crop rotation.

Bacterial Canker

Symptoms

  • It is seed borne.  It can reduce yield to 90% especially in indeterminate varieties.  The bacteria can survive in cracks on the sticks used for staking.
  • Symptoms include wilting and curling of the leaflets of the lower leaves.  Dried, whole leaves curls upwards, turn brown wither but remain attached to the stem.  The stem may split open and the pith is often discoloured.
  • Young fruits show discolouration of vascular system, they show deformation and stunting on mature fruits birds eye spots are visible.  Excess nitrogen favours its development.

Control

  • No chemical control has been found effective.
  • Planting healthy seedlings.
  • Crop rotation.
  • Field sanitation.
  • Disinfect pruning knife after pruning.
  • Avoid over fertilizing the crop with nitrogen.

Fusarium Wilt

Symptoms

  • Development is favoured by high temperature, low humidity and nutrient deficiency.  It is soil borne and survives in plant debris.
  • The symptoms include yellowing and wilting of the lower leaves, slightly dropping at high temperatures.
  • The vascular vessels appear brown.  In cool conditions it affects the root area only causing tomato root rot wilt.
  • Browning of the vascular vessels is restricted to the stem near the soil level but roots show a severe browning and decay.

Control

  • Use of resistant varieties.
  • Liming.
  • Crop rotation.

Bacteria Spot

Symptoms

  • The disease is seed born hence infection can start in the nursery.  It is spread by rain splash and sprinkler irrigation.  The disease attacks foliage but is most conspicuous on fruits.
  • Irregular dark green spots appear on the foliage which eventually dries.  It may cause blossoms to drop.  On fruit the initial spot is very small and water soaked and eventually enlarges.

Control

  • Foliar spray using copper based fungicides.

Bacterial Wilt

Symptoms

  • Rapid wilting
  • Drops of white or yellowish bacterial ooze may be visible when the stem is cut.

Control

  • Crop rotation
  • Plant resistant varieties
  • Remove and burn all infected plants.
  • Field sanitation
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