Sunflower Alternaria Blight : Alternaria helianthi
Symptom:
-
The disease is a destructive one, widely distributed wherever the crop is grown.
-
Severe reduction in seed and oil yield reported.
-
The most affected components are number of seeds per head and the seed yield per plant.
-
The disease also affects the quality of sunflower seeds by affecting germination and initial vigour of the seedlings.
-
The disease is characterised by the development of dark brown to black, circular to oval spots varying from 0.2 to 5 in diameter.
-
The spots are surrounded by necrotic chlorotic zone with grey white necrotic centre marked with concentric rings.
-
Spots first appear on lower leaves, later spread to middle and upper leaves.
-
At later stages, spots may be formed on petioles, stem and ray florets.
Management:
-
Occurrence and severity of the disease depend on the season and planting dates.
-
Mid-September planting of sunflower remains free from the disease.
-
Foliar spray with 0.3 per cent Mancozeb four times at an interval of 10 days controls the disease.
Source-
- TamilNadu Agritech Portal
