Black Sigatoka is one of the most serious foliar diseases affecting bananas. This scourge causes necrosis on the leaves and accelerates the ripening of fruits, seriously compromising yields and crop quality. In the absence of control measures, this disease can reduce banana production by half, representing a major challenge for crops in tropical regions.
What is Banana Black Sigatoka?
Black Sigatoka, also called Black Sigatoka or black streak disease of banana . This is a particularly aggressive foliar disease, which can lead to a reduction in yields of up to 50% if no control measures are taken.
It is caused by Pseudocercospora fijiensis , a fungus of the order Capnodiales and the family Mycosphaerellaceae . This pathogen targets bananas of the genus Musa , and all its cultivars such as Cavendish and Plantain species.
Black Sigatoka has spread rapidly throughout the world’s humid tropical regions . Today, it is present in almost all regions where bananas are grown. In France, territories such as Guadeloupe, Martinique, Mayotte, Reunion and New Caledonia are highly affected.
The fungus grows mainly in warm and humid environments , typical of tropical climates. These conditions favor its rapid spread. The combination of reduced yield and degraded fruit quality makes it a major threat to the banana industry, which represents an essential economic and food source in many regions.
What are the symptoms of black Sigatoka of banana?
Black Sigatoka of banana mainly affects the leaves, but its consequences affect the entire plant and the fruits. The development of symptoms on the foliage occurs in six distinct stages:
- Stage 1 : small yellowish dots appear on the underside of the leaves.
- Stage 2 and 3 : These dots develop into brown-orange dashes that lengthen and widen, sometimes reaching up to 3 cm.
- Stage 4 : Lesions appear as oval, brown to black streaks.
- Stage 5 and 6 : The affected areas become black and are surrounded by a yellow halo. The centers of the lesions take on a necrotic, grayish appearance, contrasting with the edges.
These lesions impair photosynthesis. The edges of the affected leaves fold back on themselves, and as the disease progresses, the leaves dry out completely, leaving only inactive structures.
The impacts on the fruit are equally concerning. Banana development slows, leading to smaller, lower-quality fruits. In addition to their altered appearance, the fruits ripen prematurely, making harvesting difficult to plan and reducing their market value.
This combination of symptoms on leaves and fruits results in significant reductions in yields and significant financial losses for growers.
Do not confuse Black Sigatoka with other diseases
Other fungal diseases can be confused with black Sigatoka. For example:
- Freckle disease , caused by Phyllosticta cavendishii . This disease occurs mainly on Cavendish bananas, with black spots appearing on both the leaves and the fruits.
- Yellow Sigatoka , caused by Pseudocercospora musicola . Necrotic symptoms on leaves are similar in the early stages, but P. musicola grows in slightly different environments, preferring cooler and less humid climatic conditions. In addition, its development cycle is slower than that of black Sigatoka.
Life cycle of the fungus Pseudocercospora fijiensis
The fungus Pseudocercospora fijiensis , which causes black Sigatoka of banana, can reproduce in two ways: sexually , through the production of ascospores, and asexually , through the formation of conidia. Conidia spread mainly over short distances, carried by rain or irrigation water, while the lighter ascospores travel long distances by wind.
Once transported, the spores settle on healthy banana leaves. Under favorable conditions, including ambient humidity or the presence of free water on the leaves for at least two to three hours, and temperatures around 27 °C, the spores germinate. They produce a mycelium that develops both on the surface of the leaves and deep in their tissues. This fungal development remains invisible for an incubation period of 20 to 70 days, depending on climatic conditions, before the first visible symptoms appear.
Infection often begins on rolled leaves, known as cigar leaves. This early stage favors the establishment of the fungus, which takes advantage of the reduced natural protection of immature tissues. The pathogen can also spread through contaminated tools, clothing or equipment , increasing the risk of spread in plantations.
Management and control of black Sigatoka
A set of preventive and cultural measures can first be adopted to limit its spread and reduce its impacts on crops. The following actions can reduce the risk of infection:
- Systematically disinfect tools, shoes and clothing before entering plantations.
- Destroy contaminated plant residues to limit sources of spores.
- Improve soil drainage to minimize stagnant moisture, which is conducive to fungal development. (AGROBIOTOP SOLUTION: SILIBOOST
- Maintain balanced fertilization to strengthen plant vigor.
- Use irrigation systems that avoid directly wetting the foliage.
- Reduce planting density to improve air circulation and reduce ambient humidity.
Agrobiotop’s solutions for combating Black Sigatoka
In large plantations, chemical fungicides are still commonly used to control the disease. However, their frequent application has led to the emergence of resistance in the fungus , making treatments less effective and increasing the need for chemicals. This intensification has negative consequences for the environment and worker health, while increasing costs for farmers.
Faced with these limitations, Agrobiotop offers innovative, natural and safe solutions . With a strong research and development program and expertise in agrobiology, we offer alternatives that respect ecosystems, adapted to both organic and conventional farming. These solutions reduce the pressures exerted by the fungus while preserving soils and biodiversity. By integrating preventive practices and targeted organic products, it becomes possible to effectively control black Sigatoka while maintaining sustainable and quality production.
As a solution for the drainage and decompaction of the soil of your banana crops, we recommend:
If you encounter a problem with black Sigatoka, do not hesitate to contact us for solutions on the Black Sigatoka or Sigatoka mycelium.
