Black tip is a serious disorder that occurs in orchards located close to brick-kilns. Gases like carbon monoxide, sulphur dioxide and ethylene constituting the fumes from brick kiln are known to damage growing tip of fruits and give rise to the symptoms of black tip.
Apart from these factors, irrigation, condition of the tree and management practices also play important a role in deciding the severity of the disorder.
The injury takes place from the exterior and not through the root as a medium.
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Management
— The incidence of black tip can be minimised by the spray of borax (1 per cent) or other alkaline solutions like caustic (0.8 per cent) or washing (0.5 per cent) soda.
The first spray of borax should be done positively at pea stage followed by two more sprays at 15 days interval.
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— Trees sprayed three times with a 0.6 per cent solution of borax (600g of borax mixed in 100 litres of water) plus a sticker, at the rate of 10 litres per tree were almost free from black tip.
— Planting of mango orchards in North-South direction and 5 to 6 km away from the brick kilns may reduce incidence of black tip to a greater extent.
— Although black tip of mango can be prevented by applying borax, the disease is not caused by the fruit surface that prevents direct entry of poisonous fumes or changed into a form which is less toxic.
Other control measures
Restriction of new kiln sites to a safe distance — stopping the working of kilns before the time of fruit-set and use of telescopic chimneys (12-15 m high).
Mango decline is becoming a serious problem in many parts of northern India.
On the old leaves, leaf tissues collapse in clearly defined marginal areas of brick red colour towards the tip.
Younger leaves generally do not show symptoms up to two months of their emergence.
Mallikarjun Kenganal
Byadgi, A.S.
& Benagi, V.I
Department of plant pathology, University of Agricultural SciencesDharwad