Black sigatoka is a banana disease which causes leaf variegation and thus reduce significantly the area of the leaves. It is a terrible defect to banana exporters since it causes premature ripening and leads to severe loss of more than 50%. Black Sigatoka disease is also called Black Leaf Streak disease and its causative agent is known as Mycosphaerella fijiensis. The disease can be treated by regular application of fungicides or cutting off the affected leaves. Below are a detailed ways to treat Black Sigatoka by chemical and cultural methods.
Chemical Method
Treatment of Black Sigatoka can be achieved by application of chemicals such as fungicides. Fungicides work by completely eradicating fungal infections or protect the plants from invasion by fungi. There are two types of fungicides that are deployed in the treatment of Black Sigatoka disease; protectants and systematic fungicides. Systematic fungicides are more effective since they have the capability to penetrate the plant tissues and arrest the growth of harmful fungal pathogens. Some examples of systematic fungicides include; benzimidazoles and flusilazoles.
It is recommended that systematic and protectant fungicides should be used alternately otherwise the fungal pathogens may develop resistance to the fungicides.
Mineral oil has also been proven to play an important role in treating Black Sigatoka disease. The oil works best when applied together with the fungicides, it ensures an efficient distribution of the fungicides on the leaves. It also enhances penetration and sticking characteristics of the fungicides. Besides, it can work as a fungicides on its own and retard the growth and development of fungicides.
Despite of the superiority of systematic fungicides over protectants fungicides, it is important to note that they can cause phytotoxicity especially during dry seasons.
Cultural Control
Proper management of organic manure is essential in banana production as it control Black Sigatoka disease. It is obvious that plants thriving in fertile and managed conditions would generally develop high resistance to malfunctions. Or, if there be any disorder the plants would not suffer severe damage.
For instance, enough organic matter in the soil stimulate root ramification. This implies that the banana plant will absorb more water and nutrients and therefore more functional leaves will emerge rapidly. The effect of Black Sigatoka would thus not be felt by the plant at a higher magnitude.
Mulching is another devised essential soil management practice which aid in improving the soil environment making it favorable for growing bananas. Decayed mulches or humus has got physical, chemical and biological roles in controlling black sigatoka. Biologically important as it enable development of microbial fauna which recycles necessary nutrients in the soil. A considerable quantity of phosphorus and nitrogen nutrients are also added to the soil by humus.
Others practices like pruning based on the necrotic leaf being eliminated can also be used in control of Black Sigatoka. Pruning curbs the spreading of Black Sigatoka during treatment and thus reduce the rate of infection. However, an amalgam of chemical treatment and cultural treatment is excellent.
Breeding for resistance control
Since fungicides are expensive, control by breeding and resistance could be more effective. Resistant genes are developed by interacting recessive allele and other two independent genes. The resulting dosage makes bananas or plantains less susceptible to Black Sigatoka.