Tobacco Brown Spot: Alternaria longipes, Alternaria tenuis, Alternaria alternata
Symptom:
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Brown spot in contrast to frog-eye spot is not normally observed in the nursery but is very much prevalent in the field.
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In India a decade back it was considered to be of minor importance but gradually it is gaining importance especially in tobacco grown in monsoon season.
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Initially, it appears on lower and older leaves as small brown, circular lesions, which spread, to upper leaves, petioles, stalks and capsules even.
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In warm weather (300C) under high humidity, the leaf spots enlarge, 1-3 cm in diameter, centres are necroses and turn brown with characteristic marking giving target board appearance with a definite outline.
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In severe infection spots enlarge, coalesce and damage large areas making leaf dark-brown, ragged and worthless.
Management:
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Removal and destruction of diseased plant debris can check the primary infection promptly.
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The continuous growing of tobacco after tobacco must be avoided in the heavily infected fields.
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Weekly, spraying of fungicides such as Maneb – 0.2%.
Source-
- TamilNadu Agritech Portal
