Black sigatoka

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Mycosphaerella fijiensis

Kingdom:	Fungi
Division:	Ascomycota
Subdivision:	Pezizomycotina
Class:	Dothideomycetes
Order:	Mycosphaerellales
Genus:	Mycosphaerella
Species:	M. fijiensis

Binomial name

Mycosphaerella fijiensis
Morelet

Black Sigatoka is a leaf spot disease of banana plants caused by ascomycete fungus Mycosphaerella fijiensis Morelet. Plants with leaves damaged by the disease may have up to 50% lower yield of fruit. Black Sigatoka, also known as black leaf streak, was named for its similarities with the Yellow Sigatoka caused by Mycosphaerella musicola Mulder, after the Sigatoka valley in Fiji where an outbreak of this disease reached epidemic proportions from 1912 to 1923^[1].

M. fijiensis reproduces both sexually and asexually, and both conidia and ascospores are impontant in its dispersal. The conidia are mainly water-born to short distances, while ascospores are carried by wind to more remote places (the distances being limited by their susceptibility to ultraviolet light).Over sixty distinct strains with different pathogenetic potentials have been isolated. In order to better understand the mechanisms of its variability, the "Genetic diversity of Mycosphaerella fijiensis Project" has been initiated.

In commercial export plantations, Black Sigatoka is controlled by frequent applications of fungicides. Removal of affected leaves, good drainage, and sufficient spacing also help to fight the disease. Although fungicides improved over the years, the pathogen developed resistance. Therefore higher frequency of application is required, increasing the impact on the environment and health of the banana workers.

Small farmers growing bananas for local market cannot afford expensive measures to fight the disease. However, some cultivars of banana are resistant to the disease. Research is done to improve productivity and fruit properties of these cultivars. A genetically modified banana variety made more resistant to the fungus has recently been developed and will be soon field tested in Uganda^[2].

[edit] References

Ploetz, R.C. (2001) Black Sigatoka of Banana. The Plant Health Instructor.
AGRIFOR synopsis on Mycosphaerella fijiensis[1]
Genetic diversity of Mycosphaerella fijiensis project[2]
A Peruvian website on Black Sigatoka (Spanish)[3]

^ Marín D. H., Romero R. A., Guzmán M. and Sutton T. B. (2003). "Black sigatoka: An increasing threat to banana cultivation". Plant Disease 87 (3): 208-222. doi:10.1094/PDIS.2003.87.3.208.
^ Dauwers A (2007). "Uganda hosts banana trial". Nature 447 (7148): 1042. doi:10.1038/4471042a.