Black Leaf Streak or Black Sigatoka was first recognized in Fiji in 1963. Since then, it has been found elsewhere and has steadily replaced yellow sigatoka in banana producing countries.

    The disease is caused by a fungus, Mycosphaerrella fijiensis and is considered to be more virulent than yellow sigatoka.

    When both diseases are present, black sigatoka predominates. Saba or Cardaba is resistant while Lakatan, Latundan, Bungulan, and Señorita are susceptible cultivars.

Transmission                                                                    When the conidia are released, they are disseminated by water while the ascopores are discharged during wet periods and dispersed by wind. The unfurling leaf and the first open are initially infected.

    Under a crowded canopy and humid condition, the conidia can rapidly spread the disease on a susceptible variety.

Symptoms                                                                    • Initially, tiny brown streaks appear on the underside of the third and fourth leaves.

• After the streak stage, spots develop in a similar way as in yellow sigatoka.

• Streaks elongate into reddish-brown that later become dark brown or black.

• Dense aggregation of the black streaks may form and when these areas become water-soaked, the leaf turns black, dries up rapidly, and becomes brown.

Cultivar Reaction
    All commercially grown varieties such as Cavendish, Grand Maine, Lakatan, Latundan, Bungulan, Saba or Cardaba, and Señorita are susceptible to this disease.

Control Measures                                                         1. When planting bananas, you should consider the recommended population per unit area to avoid overlapping of leaf canopy that would create favorable microclimate for disease development.

2. Remove infected leaves to prevent faster spread of the disease. Cut the whole leaf when 75% of the entire leaf is spotted. If, infection is 50% or less, the leaf must  be trimmed to remove spotted areas. However, deleafing should not be overdone.

3. Provide drainage canals to avoid waterlogging that triggers high humidity favorable for disease development.

4. Maintain proper plant nutrition.

5. Institute a planned chemical control program. For small farmers, apply fungicidal spray at the rate of 100 L/ha with either Dithane M-45 at 35 g/L, Daconil at 2 g/L, or Benlate at 1-2 g/L water at an interval of 14-21 days. Proper and adequate shaking of the spray solution must be maintained to avoid phytotoxicity on banana leaves and fruits.

For more information, please contact:
Dr. Biley E. Temanel
Isabela State University
0921-475-3011