In Summary
  • Diseases often lead to lower quantity and quality of fruits, resulting in low profits. In instances where pest and disease infestation are not controlled, post-harvest losses are high.
  • The flowers, leaf stalk and stems are also attacked, with the affected parts developing cankers, which lead to shoot tip dieback.
  • During nursery establishment, one should select a nursery site that is protected from wind and establish windbreakers.
  • The disease-causing agent survives from one season to the other as mycelium in the dormant buds and as haustoria on tender leaves.

It is another mango season and as expected, markets are flooded with the fruits, with a majority going for a song.

But as some farmers enjoy the boom, last week I visited a mango farmer in Makueni who feared losing his fruits because of increased disease infestation.

Diseases often lead to lower quantity and quality of fruits, resulting in low profits. In instances where pest and disease infestation are not controlled, post-harvest losses are high.

One of the diseases currently ravaging the mango tree is bacterial black spot, which affects leaves, stems and the fruits.

On leaves, the disease causes black angular greasy spots between the veins, which sometimes have yellow holes.

With time, these spots enlarge and destroy large areas of the leaves, which turn grey and crack, leading to reduction of photosynthetic area and high rate of leaf fall.

Affected fruits have black oval to irregular raised spots, which develop with greasy margins.

The spots are usually skin deep, but they affect the quality of the mango fruits, leading to rejection or lower selling price.

The flowers, leaf stalk and stems are also attacked, with the affected parts developing cankers, which lead to shoot tip dieback.

The disease is easily spread by windblown rain, splash water and insects. Injuries or abrasion on the plant form the entry point for the micro-organism. Affected seedlings can also spread the disease from one region to the other.

The disease can be severe in both high and low rainfall areas as dew also increases its spread.

During crop establishment, take preventive measures that include buying clean planting materials to curb introduction of the disease on the farm. It is also ideal to select varieties that are resistant and tolerant to the disease.

SEVERE LOSSES

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