The Case Studies - Black Sigatoka
Taxonomic Name: Mycosphaerella fijiensis
Common Names: Black leaf streak
Ecological Category: Fungus
Main impacts: Agricultural
Description
Black Sigatoka, or black leaf streak, is a widespread disease of bananas, caused by the fungus Mycosphaerella fijiensis. It is one of the most destructive of all the leaf diseases of bananas.
It affects leaves, reducing the photosynthetic area of the plant and subsequent banana yields. It was first identified in Fiji, but is found in most banana producing areas of the world.
Black sigatoka infected bananas
Habitat
Black sigatoka spores form readily during tropical and sub-tropical summers or under conditions of high humidity and rainfall.
Current Distribution
Mainland Australia is currently free of Black sigatoka, but since 1981 several separate incursions of Black Sigatoka have taken place in separate locations of Cape York, including Bamaga, Weipa and Tully. On each occasion the diseased plants have been eradicated, and the disease is yet to spread outside of Cape York.
Black Sigatoka is endemic in parts of the Torres Straits which lies between Papua New Guinea and Cape York Peninsula.
Soruce: Agriculture WA Factsheet No 14/2000
Dispersal / Reproduction
The spores of Black Sigatoka are primarily spread via rainwash or splash. Infection occurs on the youngest leaves of the plant during and older leaves are generally not readily infected.
Impacts
Black sigatoka causes destruction of banana leaf tissue, which affects the photosynthetic capabilities of the plant and can reduce yields by up to 50%. Black sigatoka is one of the main factors responsible for the decline in banana export industries in South Pacific nations.