Diseases of Fruit Plantation Medicinal and Aromatic Crops

Sooty blotch of apple

Sooty blotch disease

Causal organisms:a complex of fungi which includes Leptodontium elatius (G. Mangenot and Geastrumia polystigmatus Batista
Symptoms

Colonies of the fungal pathogen on the fruit resemble sooty or cloudy olive green blotches on the surface of the fruit. The fungus grows superficially on the fruit surface which can be easily wiped out.

Dissemination: Sooty blotch spores are released during rainy season and disseminated by wind.
Disease Cycle

The fungi overwinter on infested apple twigs and numerous forest trees. During rains in the spring and early summer the spores are dispersed with secondary spread occurring throughout the season. Fruit infection can occur as early as 2-3 weeks after petal fall. Infections mostly occur during periods of frequent rains and high humidity. Symptoms of infection may not be apparent until sometime (typically 20 to 25 days) after the initial establishment of infection.

Management

Key times for management: The right time for management begins 1-2 weeks after petal fall and continues until 2-3 weeks before harvest.
Cultural practices: Remove reservoir hosts from the orchard and its periphery. Sooty blotch is favoured in the humid conditions present in poorly pruned trees and in damp, slow-drying areas of the orchard. Winter and summer pruning is required so as to increase air, light, and spray penetration. Thinning fruit to separate fruit clusters facilitates the drying of the fruit after rainy periods.
Chemical: 1percent Bordeaux mixture solution spray is effective.